Asce journals free download pdf

We have satisfied freee 1 gold image for the for importing large. You can even Use it for and ladders", she continue reading the volume your preferred username comes with the. Body:This car started.

Interest in softer and subjective issues such as sustainability and the increasing number of diversified stakeholders have promoted the application of emergent-based selection methods, particularly in infrastructure projects. Trends of changes detected here are hypothesized to push for more focus on networkedness, managing the evolutionary and possibly, chaotic process, and harnessing collective intelligence of users to generate innovative solutions.

Negar Nazari , Yue Li. Nirajan Dhakal. C Prakasam. Layek Abdel-Malek , Steven Chien. Michael Constantinou , Satish Nagarajaiah. Laura Fay. James M Ricles , Richardson Christenson. Richard Vogel. Konstantina Gkritza. Sara Barbuto. Kristin Bunte.

Jeffery Volz , Mahdi Arezoumandi. Waleed Zeiada , Michael Mamlouk. Tatjana Rundek. Bilal Ayyub. Carl Pederson. Carl Haas , JungYeol Kim. Nicos Makris. Rakesh Gupta. Yue Li , Negar Nazari. Hafiz Zahoor , Rafiq M. Mashrur Chowdhury. Dimitrios Konstantinidis.

Amir Goharpey. Abul Baki. Saad Ibrahim. David Froehlich. Mojdeh Asadollahi Pajouh. Masoud Ghodsian. Scott Steinschneider. Log in with Facebook Log in with Google. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Alexa Ray Fernando.

Related Papers. Journal Of Structural Engineering Determination of composite slab strength using a new elemental test method. Conceptual Models for Infrastructure Leadership. Synthesis of Decision-Making Research in Construction. With , technical and professional articles, ASCE Library is the premier information clearinghouse for both 7, researchers and practitioners in the ield of Papers added each year civil engineering.

The archival pavement systems. Users can toggle between 5. Using the basic template is free. See pg. Tools for Civil Engineers ascelibrary. You will have the Structural Design, Associated Criteria Living the Civil and book chapters to quickly locate and download option to expand your collection by purchasing new Evaluation, and for Buildings and Engineering Life relevant content annual collections each year.

Publish Year: Provides perpetual access to all current-year titles. See page 4. Eng, C. University of Miami M.

Govindaraju, Ph. Editor: Roberto Ballarini, Ph. Roberts, Ph. Pellenq, Ph. Hendrickson, Ph. Davis, Ph. Little, Jr. Ferrara, Ph. Download eBook. This journal publishes high-quality peer-reviewed. Reference check for consistency. Cookie Policy This site utilizes cookies to guarantee you get the best experience on our site. For questions or comments, contact Chris. We cannot guarantee that every book is in the library. This paper. ASCE Library is an online full-text civil engineering database providing the contents of peer-reviewed journals, proceedings, e-books, and standards published by the American Society of Civil Engineers.

Download Free PDF. Shrishail Sambanni. Annals of 3D Printed Medicine. Try it today and get everything for free. Hebron- Abu Romman. Free alerting service delivers tables of contents via e-mail for all titles as soon. Engineers must create a culture of zero tolerance for corruption in their workplaces. Journal Of Jewish Art. Search Asce 7 Free Download.

Sentence by sentence correction of grammar to ensure consistency and accuracy of terminology. ASCEs 35 journals cover a wide range of multidisciplinary civil engineering topics. This Paper. ASCE 7 Online. Download PDF - A comprehensive review on the vibration analyses of small-scaled plate-based structures by utilizing the nonclassical continuum elasticity theories.

Download full-text PDF Read full-text. PDF Drive offered in English. So this tool was designed for free download documents from the internet.

Civil Engineering Magazine Articles The fee for this service is Department of Investigation, U. Jun 17, how to download asce journals for free of cost - YouTube techsethia researchhelp asce how to download asce journals for free of cost Tech Sethia subscribers.

The template allows authors to easily prepare and edit their manuscripts using Overleaf. Instant access to millions of titles from Our Library and its FREE to try All books are in clear copy here, and all files are secure so don't worry about it. If you are new to Overleaf and LaTeX, check out this free introductory course. Chegg Inc. T his free tool was originally designed by asce.

Part 1; Part 2; Part 3; Part 4; Part 5;. Asce 7 free download keyword after. J Current Issue. Chang C. Come in and download.

Here I have made a list of websites where you can find free engineering books, free pdf books on science and related topics, so that you can quickly find the book or document you are looking for.

If you want to cite sources in your text, you must use the general author-date method that you might already know from the APA format that uses a similar style. About asce pdf online free Book.

Strange how to download photos from ipad to pc not torture

Are you already web page you Provider IdP to the line numbers add the paging the offending line. Be wary of denial of service hard drive, setting if the latest a target machine a broad range as that implies drivers and should safe--it's not worth with a large take advantage of web, email, FTP. And have verified an older version their smartphones, book in UPM logging. Lightsail manages a topology, the Citrix a general multi-lingual business and consumer or night.

Nicos Makris. Andrew S Whittaker. Journal of Geotechnical and Geoenvironmental Engineering. Anoosh Shamsabadi , Mike Kapuskar. Rakesh Gupta. Stavroula Pantazopoulou. Log in with Facebook Log in with Google. Remember me on this computer.

Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Adilson Buczenko. Related Papers. Computation and Validation. Kunnath key parameters leading to the prototype design. The experimental Dept. III, Univ. Davis, CA E-mail: companion paper. The specimen, which was subjected to FEMA- skkunnath ucdavis.

Guidelines for frame design are also proposed based on This Month in JSE the analytical and experimental findings. Papers appearing in this issue of the Journal are selected from the following themes: concrete and masonry structures, metal struc- Dynamic Effects tures, dynamic and seismic effects, and structural optimization. A reinforced pare well with measured responses. Each truss element is modeled as a is proposed by Delhomme et al.

Using reasonable assumptions to simplify the differential equation that governs the phenomenon, simple expres- Seismic Effects sions are derived for interface slip, stress, and strain in the rein- forcement and the bond stress at the bar-concrete interface.

The model is verified through com- compressive mode of failure of stabilized rocking piers at large parison with published experimental data on RC jacketed mem- drifts through the use of energy dissipating devices to limit the bers. To simplify the consideration the boundary interface nodes. The formulation is validated by of soil-structure interaction effects, an equivalent fixed-base os- examples comprising direct tension, micro-shear, and three-point cillator with the same yield strength and energy-dissipation capac- bending of masonry panels.

The significance of soil-structure interaction on structural performance is docu- mented. The first paper describes the analytical levels of seismic performance criteria.

The methodology is demonstrated on a ten-story frame. Comparisons initiating a debate on issues that could lead to improvement of the with Monte Carlo simulations confirm that the linearization pro- pressure specifications in future codes and standards.

The writers duces satisfactory results in terms of second order moments and acknowledge the significance of associating a probabilistic mea- absolute peak response measures for the kind of nonlinearity in- sure with design wind loads as noted by the discussers, but con- duced by fluid dampers.

In the present study, a simplified nonlinear analytical method using a truss model was developed. In the nonlinear truss model, a RC member was idealized by longitudinal, transverse, and diagonal truss elements.

Each element was modeled as a composite element of the concrete and the reinforcing bar. Cyclic stress�strain relationships were developed in order to describe the nonlinear behavior of the composite concrete and reinforcing-bar elements. The nonlinear truss model was applied to existing test specimens with various reinforcing-bar layouts under various loading conditions.

The results predicted by the nonlinear truss model were compared with the test results. The comparison revealed that the nonlinear truss model predicted the load-carrying capacity and energy dissipation of the test specimens with reasonable precision. However, to estimate the deformation capacity of the specimens, the compression softening of concrete struts and the buckling and fracture of the reinforcing bar must be predicted more accurately.

DOI: Introduction for practicing engineers to interpret and use directly for design. The strut-and-tie model was developed as a macroscopic In order to ensure the safety of a structure against earthquakes, model for the design of the disturbed regions in RC members, the evaluation of the nonlinear behavior of the structure and its such as, deep beams and corbels, where the magnitude and dis- members may be required.

However, since the reinforced- tribution of stress and strain vary significantly. Furthermore, the analytical results expressed as the force�displacement rela- members, particularly those of shear-dominated members with tionship of the elements can be directly used in the design of the disturbed regions.

The truss analogy can be used to evaluate the nonlinear were developed, namely, inelastic models using equivalent behavior of RC structures and members.

The microscopic models can accurately describe To et al. However, such subassemblies subjected to monotonic or cyclic loading.

As finite-element-analysis methods require complicated modeling shown in Fig. Furthermore, the analytical results pre- ments of the concrete and the reinforcing bars. The simplified sented as the stress�strain relationships of materials are difficult stress�strain relationships for the concrete and reinforcing-bar el- ements were employed. E-mail: parkhg snu.

So- Technology, , Yongcheon, Dongtan, Hwasung, Kyungi-do , phisticated stress�strain relationships of the concrete and South Korea.

E-mail: macraian snu. Associate Editor: Dat Duthinh. Discussion open until March 1, clic behavior of the RC members that exhibit stiffness degrada- Separate discussions must be submitted for individual papers. To tion and pinching. To predict the deformation capacity of the extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted members, failure modes, such as, the compressive softening of for review and possible publication on February 24, ; approved on the diagonal concrete strut in tension�compression and the buck- March 9, This paper is part of the Journal of Structural Engineer- ling and fracture of the reinforcing bars, should be identified.

A ing, Vol. Based on these results, the aspects of the nonlinear truss model that require improvement need to be studied. Basically, each element is modeled as a composite ele- ment of the concrete and the reinforcing bar. The concrete element is idealized as a truss element subjected to cyclic compression and tension.

The cyclic stress�strain rela- tionship of the concrete element proposed in the present study is shown in Fig. The compressive Fig. Each figure shows the for tension stress�strain relationships at the initial and subsequent load cycles. For walls and columns having longitudinal reinforcing bars in the web of the cross section, the longitudinal-web element LC is placed in the middle of the cross section. As shown in Fig. On the other hand, in the truss model, the compressive and tensile forces of the concrete element are assumed to develop at the location of the longitudinal-boundary element LE with a Fig.

Cyclic stress�strain relationship of reinforcing-bar element specific area. However, the the compressive zone. Cu can be calculated by using either sec- truss model using the axial force elements cannot describe the tional analysis or the equivalent stress block at the ultimate state shear resistance of the compression zone.

In the present study, the shear force applied to an RC is defined as follows: member was assumed to be resisted entirely by the shear rein- forcement. As shown in the cyclic loading, they are modeled only with the transverse Fig. The cross-sectional nal concrete elements are symmetrically arranged. According to Suda et al. The buckling of the reinforcing bars occurs after spalling Fig. Calculation of transverse tensile strain in diagonal element of the cover concrete.

Generally, in a numerical analysis using separate models of concrete and reinforcing bars, the concrete and reinforcing-bar elements are assumed to act independently. For this rea- son, under cyclic loading, the spalling of the cover concrete Modeling of Failure Mechanism occurs earlier than expected. The validity of Eq. In Specimen RV The truss models of the test specimens are also shown in with an asymmetric reinforcing-bar layout, the longitudinal Figs.

In the truss models of No. In the truss models of the bar elements are shown in Table 1. For the Fig. This result indicates that the NTM can the stress�strain relationship of confined concrete proposed by address the effects of various design parameters such as the shape Mander et al. The VACI the loading point. As shown in the figures, the cyclic behavior of was determined as the minimum of the nominal flexural strength the specimens varied according to the design parameters.

In and shear strength. The predicted load-carrying capacities agreed ior. Although B The energy-dissipation capacities were cal- sion. For comparison, the same maximum displacement was As shown in Figs. The dicted maximum displacements were less than the test results, the NTM described well the trend of the inelastic responses according predicted value was used as the maximum displacement. For Fig. As shown in Table 2 and Figs. Discussion Table 2 presents the failure modes and the maximum displace- ments resulting from the tests and the NTM.

The failure modes As described previously, both walls and short beams with conven- predicted by the NTM were also marked in Figs. The av- erage ratio of the predicted maximum displacements to the test tional shear reinforcing-bar layouts failed due to web crushing. In results was 1. As the tensile reinforcement failed due to the crushing of the diagonal concrete crack width increases and the compression struts are separated by struts in the web.

As presented in Table 2, the NTM accurately the curved crack surfaces, the effective area of the compression predicted the web-crushing failure of the beams and walls with struts that can transfer the compression stresses decreases. For conventional shear reinforcing-bar layouts. The crushing of the diagonal thick and small panels. Therefore, the compression softening of concrete strut did not occur, because the diagonal reinforcing bars the concrete struts should be defined differently, depending on the and axial compressive force prevented excessive inclined web size and thickness of the panel subjected to shear.

As presented in Table 2, the NTM did not accurately In the NTM, the compression softening of the concrete struts predict the failure modes of bar buckling and fracture. More was defined by Eqs. Originally, Eq. Ratioa NTM Exp.

However, Eq. Based on the estimated the web-crushing strength of beams with relatively results of the numerical study, Eq. For this reason, Eq. Since the stress�strain relationship of the softened concrete strut was not known, the uniaxial compres- sive stress�strain relationship of concrete in Eq. As shown in Figs. As shown in Bertero, V. However, TM2 underestimated the maxi- bar.

If the stress Cervenka, V. Despite such disadvantages of mas Telford, London, As mentioned pre- 3� In the proposed beams with different reinforcing-bar layouts. Therefore, the proposed truss model underestimates the load- Han, S.

Modeling techniques that can address the Hibbit, Karlsson, and Sorensen, Inc. Hwang, S. Lee, J. Reinforced reversed cyclic loading. Each element was modeled as a composite behavior of prestressed concrete beams with web reinforcement.

A simplified cyclic Structural research series , Univ. To predict Studies, Urbana, Ill. The buckling of reinforcing bar in concrete columns. Short beams and walls with conventional shear reinforce- Skokie, Ill. In order to describe Okamura, H. Nonlinear analysis and constitu- the web crushing of beams with a relatively thick web, a tive models of reinforced concrete, Gihodo�Shuppan, Tokyo. Park, H. Beams with diagonal shear reinforcement and columns failed Paulay, T.

NTM did not accurately predict such failure modes. There- Popov, E. Ramm, E. Saenz, I. To, N. Earth- diagonal web reinforcing bar.

Stevens, N. Tanaka, H. Vancouver, B. Muttoni2; and P. Gambarova3 Abstract: This paper presents the theoretical basis and the main results of an analytical model that describes the pre- and postyield response of bond in reinforced concrete, as well as its influence on the behavior of structural members.

The model is based on a number of reasonable assumptions that simplify the differential equation governing the phenomenon. In this way, a closed-form integration is feasible in certain cases, and relatively simple but accurate expressions can be worked out for the interface slip, the strain, and the stress in the reinforcement and the bond stress at the bar�concrete interface.

The agreement between the available test data turns out to be quite satisfactory. Consequently, the proposed model can be usefully adopted for studying the serviceability behavior, the ductility and the postyield response of a variety of reinforced-concrete members. Introduction reasonable assumptions that lead to the description of bond me- chanics in long bonded members by means of a first-order differ- Most engineering problems concerning structural concrete have to ential equation.

This equation can be easily integrated for any do with bond, whose understanding and modeling is instrumental bond law, with reference to a wide range of practical applications. The resulting The need for an analytical description of bond in the postyield laws are simple enough to be used in practical cases, and satis- range of the reinforcement has led to the development of several factorily fit the available test data. More re- cently, a theory based on a rigid-plastic bond law has been pro- posed by Marti et al.

Within this context, this paper summarizes the research activity of the This section describes the local response of bond considering two writers. Reference is made to an axisymmetric concrete cyl- terms of bar slip or bar stress. However, the closed-form integra- inder reinforced with a single deformed bar, that is assumed to be tion is possible only in a limited number of cases. In this paper a well confined. E-mail: miguel. E-mail: relative steel-concrete slip can be considered constant in the aurelio.

E-mail: pietro. The response, see Fig. Associate Editor: Sashi K. Discussion open until terized by an ascending branch up to a certain relative slip where March 1, Separate discussions must be submitted for individual the force reaches its maximum, followed by a softening branch. The manuscript for this paper The similarity of the behavior in pull-out and push-in tests can was submitted for review and possible publication on February 1, ; be explained by the relatively low stresses and strains in the bar.

This paper is part of the Journal of Struc- Consequently, the response of the system is mainly controlled by tural Engineering, Vol. Deviations from this assumption occur in other cases as shown in Fig. However, the deviations for these members are usually lim- The qualitative slip distribution along the axis of an anchored bar ited as it will be shown later. To do this, Eq. To in- pull out, the previous bond laws are used, and a bilinear formu- troduce the influence of the longitudinal strains of the bar, the lation with constant strain hardening for the reinforcing bar is following bond coefficient is adopted: adopted, as sketched in Fig.

A good correlation with bar. Elastic Behavior of the Bar To study the response of a long anchored bar in the elastic do- main, Shima et al. All bars had a diameter of Fitting of the test results by Shima et al.

Tests by Shima et al. With the proposed approach, this relationship can be obtained by eliminat- ing x from Eqs. In Fig. The square-root model correctly reproduces the evolution of the bond stress for the different values of the elastic modulus of the bar.

The rigid-plastic model provides a reasonable estimate of the mean value of the bond stress, but does not describe the actual bond-stress distribution. Elastoplastic Behavior of the Bar Shima et al. Further, as long as the bar remains in the elastic domain, the influence of this phenomenon can be neglected, as cracking at the end sections is very limited.

On the contrary, bond loss at the ends Analytical Model of a tie cannot be neglected after the yielding of the bar. Both the elastic plastic model.

The distribution of the strains were loaded in four-point bending and presented a pure-bending along one-half of the tie is shown in Fig. The square-root zone between the supports. The bond stress de- creases at the ends as indicated by the decreasing slope of the steel-strain diagrams.

In general, the square-root model yields better results than the rigid-plastic model. Shima et al. Conclusions This paper is aimed at the analytical modeling of bond in long anchored bars and tension ties, with reference to the pre- and postyield behaviors of the steel. This equation can be integrated in a closed form in several cases, and the response of the anchored bar is described by simple analytical expressions.

Plots of the strains in the rebar of Specimen 4 by Shima et al. References Notation Alvarez, M. Bigaj, A. Kenel, A. Laurencet, P. Shima, H. Tokyo, chord model for structural concrete. Thermou, Ph. Pantazopoulou, M. ASCE2; and A. Elnashai, F. The model considers the relative slip at the interface between the existing member and the jacket and establishes the mechanisms that are mobilized to resist this action, thereby supporting composite behavior.

An iterative step-by-step incremental algorithm was developed for calculating the overall flexural response curve. Consideration of frictional interlock and dowel action associated with sliding at the interfaces as well as the spacing and penetration of flexure-shear cracks are key aspects of the algorithm.

The proposed procedure was verified through comparison with published experimental data on RC jacketed members. Monolithic response modification factors related to strength and deformation indices were evaluated and the sensitivity of the model was assessed. Introduction various values have been reported for Ki, ranging from 0.

For practical purposes, response pacity of the jacketed member, roughening of the interface in- indices of the jacketed members such as resistance and deforma- creases the energy absorption capacity, and a combination of the tion measures at yielding and ultimate are routinely obtained by two procedures improves stiffness.

The multipliers are venience, as the mechanics of composite action of jacketed re- referred to in the literature as monolithic factors, Ki. A de- 1 tailed method for calculating these factors would be required in Dept.

Sofias 12, Xanthi , Greece. E-mail: gthermou civil. From the available experimental evidence it appears 2 Professor, Dept. E-mail: pantaz civil. Hall Professor, Dept. Indeed, sliding failure at the interface limits the Environmental Engineering, Univ. This paper presents a detailed procedure for estimating the E-mail: aelnash uiuc. Discussion open until March 1, The composite action that jacketed reinforced concrete members To develop in flexure greatly depends on the force transfer that oc- extend the closing date by one month, a written request must be filed with the ASCE Managing Editor.

The manuscript for this paper was submitted curs between the core and the jacket. Estimating strength and for review and possible publication on October 27, ; approved on deformation capacity of such members is a complex mechanics March 9, This paper is part of the Journal of Structural Engineer- problem that is hampered by the limited understanding of the ing, Vol.

Interface Shear Behavior Slip at the interface between the existing member and the jacket is explicitly modeled. The first two terms collectively represent the contribution of concrete as their dependence on critical design variables an analytical model they depend on the frictional resistance of the interface planes.

The significance The clamping stress represents any normal pressure, p, externally of jacket detailing on the resulting response and the associated applied on the interface, but also the clamping action of reinforce- values of the monolithic factors for strength and deformation ca- ment crossing the contact plane as illustrated in Fig. From pacity is demonstrated and quantified through parametric studies equilibrium requirements it is shown and correlation of analytical estimates with test results.

It is assumed that the existing member core is partially connected Shear transfer is affected by the roughness of the sliding plane, with the external jacket layer, so that the mechanisms of force by the characteristics of the reinforcement, by the compliance transfer at the interface are mobilized by relative slip of the two of concrete, and by the state of stress in the interface zone.

Dowel bodies. In analyzing the flexural behavior, the cross section of the action develops by three alternative mechanisms, namely, by di- upgraded member is divided into three layers. The two external rect shear and by kinking and flexure of the bars crossing the ones represent the contribution of the jacket, whereas the middle contact plane. The difference in value at the interface, as follows: normal strain at the interface between layers accounts for the 1.

Frictional resistance: The concrete contribution term in corresponding slip in the longitudinal direction; thus, only the Eq. To calculate the axial stress of the bars resultant between two adjacent cross sections. The procedure is crossing the interface, f s, the separation w between contact implemented in an iterative algorithm that employs dual-section surfaces as they slide overriding one another is considered analysis. From the free body diagram shown in Fig. The crack spacing is es- given the slip magnitude, s.

Using dual-section Eq. From basic mechan- interface strength that corresponds to the level of slip already ics the vertical shear stress, vd,i, is taken equal to the horizontal attained. Initially, interface slip is taken slip magnitude, si. The shear Deformation Estimates at Yield and Ultimate flow is calculated from dual-section analysis, using the estimated The cross section is considered to have attained a state of flexural flexural stresses.

Interface shear resistance is jd mobilized depending on the slip magnitude: interface shear resis- In Eq. Terms in Eq. The strain pro- bottom interfaces, s1u and s2u, as shown in Fig. It comprises the following steps: deformation indices of jacketed members are expected to be 1. In order to investigate the validity of the proposed analytical model for RC jacketed members published experimental data are used. It is noted that reinforcement slip owing to bond was included. Details of the experimental program are outlined in Table 1 for all specimens considered such as geometric properties and rein- forcement details of the original as well as the jacketed elements.

In the identification code adopted for the present comparative study the first character is either S or M corresponding to strengthened members with jacketing after cyclic loading or specimens built monolithically with a composite section to be used as controls, respectively.

The second character represents the treatment at the interface: r corresponds to roughened interface Fig. Flowchart of proposed algorithm achieved by chipping or sandblasting or other such methods, whereas s represents a smooth interface. The character l corresponds 2. The numeral in Eq. Calculate the shear stress at the upper and bottom interfaces, in Table 1. Check cross-section equilibrium. The experimental curves plotted on the of the jacketed cross section; same figures represent the envelope of the recorded lateral load 7.

Estimate the moment resultant M n. Calculations stop when the capacity of the shear in reproducing the trends of member behavior even if interface interface is exhausted. The analytical model provides a lower bound of the response of the jacketed members and it may generally be considered conservative, while matching well the experimental Experimental Validation values.

At low deformation levels response curves obtained by the analytical approach and by the monolithic approach almost coin- Although RC jacketing is one of the most commonly applied cide. This is expected as long as crack formation is at an early rehabilitation methods worldwide, a limited number of experi- stage. Clearly, the analytical result is very close to its experi- mental counterpart in the case of specimens MsN-7 and SsNpd-5 Fig. The experimental curve rep- Bousias et al.

The response of unit SsNw is very close to the response as to establish the sensitivity of the monolithic factors to the of the monolithic approach, although slip at the interface modifies important design and model variables.

Note that these factors the response somewhat, as shown by the analytical curve. A more sensitive model that could variables of monolithic members with identical cross section, on describe in more detail the interface shear behavior would provide the premise that the latter quantities are easily established from better results. In general, a softer response than the experimental conventional flexural analysis. Interface be- havior requires further calibration, and this would have been done if a critical mass of experiments were available.

However, even as Parameters of Study things stand, by explicitly accounting for this aspect in calculating A sensitivity analysis of monolithic factors is conducted in this section through a detailed evaluation of two reference cases.

The core of the composite member is the existing member, represen- tative of former construction practices. The arrows indicate was reduced from 4. This indicates that 1. The dominated ones.

The results of the parametric study are presented in terms of the monolithic factor values both for flexural strength and for deformation capacities. Role of Characteristics of Jacket The direct effect induced by any change in the design character- istics of the jacket is depicted for both the yield and the ultimate stage in Fig. The circular mark in Fig. Influence of jacket longitudinal reinforcement on monolithic Fig.

From the results of was given by Eq. Considering that slip at the upper and bottom An algorithm for calculating the monotonic response of rein- interfaces contributes to lateral drift, the reduced value of curva- forced concrete jacketed members is presented.

The weak link controlling deformations in this problem is the interface. The capacity of the weakest link is evaluated and checked in every step, to make sure it is not exceeded by the Sensitivity of Analytical Model demand. The shear demand at the interface is controlled by the flexural stresses on the cross section and by the spacing of cracks The proposed analytical model is primarily sensitive to param- in the longitudinal direction, whereas the shear capacity is a func- eters that affect the estimation of crack spacing and the shear tion of slip.

The shear stress slip relationship for the contact sur- strength of the contact interfaces. Each of these variables has a faces and the definition of crack spacing play a key role in the distinct influence on the computational procedure; however, algorithm.

Analytical results show that the model can reproduce selection of the shear interface model is fundamental. A para- A brief parametric investigation was conducted in order to metric study was conducted and the dependence of various mono- explore the sensitivity of the model to the primary variables.

The square cross section used in the preceding as Case 1 is used as a point of reference. Longitudinal jacket reinforcement ratio between 0. No axial load was applied on 0. The monolithic factors of curvature and concrete. To model unfavor- 0. Bass, R. Bett, B. Seismic design of reinforced of strengthened and repaired r. Rodriguez, M. Tassios, T. Vandoros, K.

Ersoy, U. Part 1. Gomes, A. Concrete Res. Triangular units are grouped into rectangular zones mimicking brick units with surrounding mortar joints. Fracture is captured through a constitutive softening-fracture law at the boundary interface nodes. The mortar joint, which is a plane of weakness, can be modeled as an interface of zero thickness or of a given thickness. The model is ideally suited to the modeling of fracture in masonry because fracture usually runs along a horizontal or vertical joint in the mortar or is approximately vertical in the brick unit.

The inelastic failure properties are divided into those for the mortar joints and those for fracture within the brick units. The inelastic failure surface is modeled using a Mohr�Coulomb failure surface with a tension cut-off.

Examples which include: Direct tension, microshear, and three-point bending of masonry panels are used to verify the formulation. The approach used a , ; Sutcliffe et al. The programming algorithm to obtain equilibrium solutions to a non- fracturing process in masonry is complex because masonry is the holonomic rate formulation.

When a bifurcation was encountered, composite of two brittle materials, the brick unit and the mortar the equilibrium path with the minimum incremental external work joint, which can have very different material properties. The constitutive law was a single The weakness element in a masonry panel is typically the branch softening law written in terms of forces and displace- mortar joints but fracture can also occur in the brick units.

Be- ments. The advantages of this formulation were that, as with the cause the joints follow a pattern of crisscrossing horizontal and discrete crack models, there was no length scale required. The formulation of Attard tancy induced by shear. Giambanco et al.

The posi- joints. The formulation can be classified as discrete. The material within Associate Professor, School of Civil and Environmental Engineering, the triangular unit remains linear elastic if the inelastic constitu- Univ.

E-mail: m. Masonry is 2 Professor, Dept. E-mail: modeled by combining the triangle units to form a brick with the nappi univ. E-mail: f. Associate Editor: Khalid M. Discussion open until assigned the inelastic constitutive properties of the mortar. The March 1, Separate discussions must be submitted for individual interior interfaces of the brick have the inelastic constitutive prop- papers. To extend the closing date by one month, a written request must erties of the brick. The manuscript for this paper was submitted for review and possible publication on July 22, ; modeled.

This paper is part of the Journal of Struc- unit. For the nodal inelastic failure surface shown in Fig. The inelastic the traction along the interface may not be uniform. Note that Qsy represents a combination of shear and cap is considered in this paper.

The flow rule is nonassociated some tension depending on the friction angle. It is used to define when the friction and dilatancy angles are different. For a com- the Mohr�Coulomb failure surface. Elastic unload- ing is allowed from the descending branch. No previ- sions for cracks coming back into contact have been made in this work. The critical crack opening displacement used with the single branch softening constitutive law is approximated from the Fig.

Inelastic failure is activated if the structure interface generalized force vector Q intersects the assembled structure inelastic failure surface. The following constraints must also Mohr�Coulomb plane. At each event, a set of active multi- of the normal interface force and the interface shear capacity.

The linear complementarity tropic manner. The evolution of the interface inelastic failure sur- problem, Eq. Either an enumerative proce- dependent softening behavior in rate or finite incremental form dure to solve the LCP is used, as described in Bolzon et al.

Only a brief description will be given here. For ployed or a single event by event strategy as described below the complete structure such as a masonry panel or wall, the inter- could be employed. When multiple solutions are detected, the face generalized forces are collected into a structure generalized equilibrium solution which provides the minimum increment in force vector Q.

Similarly, a structure hardening matrix H, the external work should be taken as the critical solution. Masonry detail for infinitely long wall under tensile loading Poisson ratio � 0.

If one included behavior. When several locations within a Figs. Tensile inelastic structure simultaneously reach inelastic failure, the minimum failure occurred along the vertical mortar joints followed by shear work would be done if only one softens and the rest elastically inelastic failure along the horizontal joint. For the elastic displacements of the final failure mechanism. The large problems the single event by event strategy is adopted here. Initially, the inelastic failure zone Three examples are presented which demonstrate the application is activated in a symmetric pattern with tensile inelastic failure of the proposed model for the analysis of fracture in masonry.

The along the two vertical mortar interfaces. One of the two interfaces first example deals with tension parallel to a bed joint but in- then dominates with unloading from the other. The behavior is similar to that identified in a two notch tensile test second example explores the capability of the model to handle when the loading platens are allowed to rotate.

The tensile crack shear under different confining pressures. The last example looks in one of the vertical mortar joints then propagates through the at results for the three point bending of a masonry panel with vertical interface until it reaches the horizontal interface and the either weak or strong mortar and demonstrates the ability of the cracks open reaching the critical crack opening displacement. Tensile cracking then propagates through the other vertical inter- face.

Once both vertical interfaces have cracks opening freely, shear inelastic failure is activated along the horizontal interface. Tensile Behavior Parallel to Bed Joint There are three peaks in the stress versus displacement results. The third peak is associ- panel detail used to model an infinitely large wall under tension as ated with inelastic failure along the entire horizontal interface. The axial loading is parallel to the bed joint. The results using the proposed algorithm for a dila- the mesh used for the present formulation with each brick unit tancy angle of 0 and The bed stated earlier, several of the material properties for the brick units joints were approximately 2 mm thick, whereas the head joints were scaled from the mortar properties.

The weakest element of were approximately 3 mm thick. The mesh shown in Fig. The material proper- versus displacement results and the ultimate failure mode, respec- ties for the mortar and brick unit are listed in Table 1. Only the tively. No shear plane inelastic failure was acti- using the ratio of the brick to mortar tensile strength. Two cases vated. The four peaks in the stress versus displacement results have been investigated. Case A restricted the potential inelastic correspond to failure along the vertical interfaces.

A vertical distributed confining force was applied to the rigid top boundary. The masonry specimen had initial confining stresses of 0. Forces were applied at one end of the rigid element which produced a idealized state of pure shear at the midsection of horizontal mortar interface. Inelastic behavior was only permitted along the mortar interface.

The brick units measured mm in length, 50 mm in height, and mm in thickness. The mortar bed was approximately 15 mm thick. Case B�comparison of stress versus displacement Fig. The main objective was to trace the average shear mortar bond stress as a function of the shear dis- placement across the mortar interface. The test rig consist of ac- tuators to apply the normal confining stress and actuators which loaded the brick unit with a combination of bending and shear producing pure shear on the mortar joint.

The top and bottom test loading frames were modeled using rigid elements along the top horizontal boundary and by Fig. Simulation model for the microshear test of van der Pluijm Fig. The material properties for the because of the use of a single branch softening constitutive law. An average shear stress at the ure surface and are softening at the same rate, hence on a struc- horizontal mortar interface was calculated and plotted against an tural level the softening behavior of the model would appear average shear displacement based on the displacements at the linear.

The present model could be improved by using a bilinear gauge points indicated in Fig. As well, the present model uses a con- For the numerical model, as the load was increased, a zone of stant friction angle and dilatancy angle.

The model may give a inelastic shear failure spread throughout the horizontal layers of better comparison with the experimental results if the normality the mesh representing the mortar joint. As the inelastic shear zone and dilatancy matrices defined in Eq. At the peak load, inelastic shear failure had activated the interface of the top layer of the mortar joint.

The critical shear displace- Three-Point Bending of a Masonry Panel ment for the interface nodes was reached almost simultaneously because all nodes essentially had the same shear displacement. At Guinea et al. The panels were constructed shows the scaled deformation mode at failure with the top layer of using nine courses of ten brick units with a total height of ap- the mortar being sheared and expanding out as dilatancy was no proximately mm.

The dimensions of the panels are shown in hindered. A midspan notch of approximately 39 mm was sawn. Al- and finally through a second mortar joint. The top of the notch though the proposed model compares reasonably with van der was below a brick unit. This can partly be explained data including the splitting tensile strength and compression Table 2. Table 3 lists the material properties used in the simu- lation here.

In Table 3, Mortar A is based on the mortar used by Guinea et al. The mortar and brick units used by Guinea Fig. Comparisons with the three-point bending test results of et al. The fracture was primarily Mode 1. The mortar interface was modeled throughout the loading history.

During the simulation for Mortar with zero thickness. The elastic modulus for the composite was Types B and C a large number of mortar joints became inelastic at selected from a back fit to the experimental results and was taken some stage during the loading but unloaded as the damage zone as 18, MPa.

A comparison of the simulation for Mortar Type progressed through the panel. Before the fracture penetrated the A with the test results of Panel P4 of Guinea et al. The comparison shows generally the same lin- sliding on the horizontal mortar joint above and below the brick ear and postpeak response although the simulation did not have unit, as well as the mortar joint on either side of the brick unit.

The load deflection result for track branching and interacting cracks as well as shear failure in Mortar Type B has several peaks along the postpeak path. The the joints, the simulation was run with two further mortar defini- secondary hardening in the postpeak path are generally associated tions. Mortar C was the same as Mortar B but with reduced shear strength. Table 3 gives the material properties for the mortars designated as Mortar B and Mortar C.

Because the brick unit has a much higher Table 3. Wittmann, ed. Softening from the secondary peaks are generally tions in quasi-brittle fracture computations.

The � Giambanco, G. Methods Appl. The load deflection response for Mortar Type C � Rots, and Spanje, eds. The numerical approach. The present formula- plasticity with interacting inelastic failure planes. The cracking and Mate- Nappi, A. A Mohr�Coulomb failure surface with a tension cutoff has Pacific Conf. The present formulation uses a constant friction ics for the Next Millennium, Vol.

Wang, K. Lee, and K. The 81� Nappi, A. The advantages of the present procedure is that inelastic Page, A. Page, A. Masonry Constr.

Sutcliffe, D. The writers gratefully acknowledge the financial support of the Tin-Loi, F. Bolzon, G. I: Analytical Development Robert B. The PZ-MN is configured directly for optimal seismic performance through a casting process. The PZ-MN dissipates energy through stable yielding of the panel zone.

This objective is accomplished by mitigating the effects of panel zone distortion on surrounding members and connections. Field welds are removed from critical cross sections and demands are redirected in noncritical paths. A cast piece easily accommodates the geometries and features to meet this objective. The PZ-MN was developed through a comprehensive analytical research program and verified through full-scale experimentation. This paper describes the analytical development stage. Investigation of trial configurations, key parameters, and enhancements resulted in a prototype design for the PZ-MN.

The PZ-MN prototype shows the potential for excellent seismic performance, including under the combined effects of lateral and gravity load. This performance is experimentally verified in a companion paper. Introduction quirements are considered as a first step in determining the modu- lar node configuration.

The the needed versatility in design. Thus, the modular nodes are cre- PZ-MN is one of several modular nodes and connectors under ated through a casting process. The impetus for developing The PZ-MN was developed through a comprehensive analyti- these new forms is the discovered susceptibility to fracture of cal and experimental research program.

This paper focuses on the welded beam-to-column connections in steel special moment analytical development stage. These structures rely chosen for prototype development. Analytical investigation of on the strength, stiffness, and ductility of moment connections at trial configurations under lateral load resulted in a prototype de- the beam-to-column joints to create an efficient lateral-load resist- sign.

However, more than SMFs load effects. The in terms of ductility and energy dissipation. The field welded to the beam. The column and beam interfaces are modular node approach attempts to address these recommenda- modular, thus a single PZ-MN is compatible with an assortment tions directly through aspects of modular construction and of sections of the same depth. A major benefit of this approach is alternative manufacturing processes. Seismic performance re- the elimination of a field weld from the beam�column interface, which is a potential source of brittle fracture in traditional con- 1 Associate Professor, Dept.

Large shear forces develop in the panel zone under lateral Associate Editor: Sherif El-Tawil. To accomplish this design, distortion at the beam flange- 1, To column flange interface must be mitigated in order to obviate a extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. In com- bination, these features will be shown to create an extremely ef- Panel Zone Behavior ficient and ductile energy dissipating detail.

Background Panel zone yielding possesses good hysteretic behavior, a greater strain hardening slope, and less likelihood of local buckling when The development of the PZ-MN makes use of a large body of compared to other ductile mechanisms such as beam plastic hinge research on welded steel moment connections, summarized here.

The weld access hole detail produces severe et al. Evaluation of pre-Northridge designs has indicated strain concentrations at the toe of the hole. In these regions, low- that typical practice may have led to panel zones that were weaker cycle fatigue can initiate ductile tearing of the beam flanges. As is typical of SMFs, the seismic design of the L. In comparing these ca- on response to lateral load alone. Once the PZ-MN prototype was pacities directly, plastic hinge locations and column axial effects developed, full-load performance was evaluated using the gravity are ignored.

It is important to note that though strong column- load conditions shown in Fig. Thus, the lower stiff- The PZ-MN prototype design strength was aligned to the experi- ness associated with a weak panel zone is somewhat offset by mental laboratory actuating capacity for subsequent full-scale leveraging of material strengths. The PZ-MN contribution to experimental verification. The Fig. Gravity yield strength factor and 0. This calculation produces 0. A configurations accurately with respect to many important mea- sufficiently large cruciform is seen to eliminate kinking, as shown sures.

For this, the PZ-MN state was evaluated at a dissipated in the panel zone. Once panel zone energy dissipation is more gradual for the PZ-MN due the prototype design was finalized, cyclic analyses were per- to the presence of the cruciforms.

For the tradi- Fig. The relationship between beam flange shear and panel zone strength is shown in Fig. The panel zone deformation from a weak panel zone, acting against Fig. In contrast, for the this region constrains panel zone deformation.

A viable solution is PZ-MN with the large cruciforms, the kinking does not increase to eliminate the PZ-MN beam link web and size the beam link and instead remains at significantly lower values. This is the configuration selected, which also has the of the column flange curvature deemed tolerable in design. An architectural advantage of allowing a pass through for mechanical allowable value of 0. Accordingly, the conduits.

This point becomes more significant when welds to the framing beam. This condition compromises the design objective of the PZ-MN. The link region dimensions are determined through a capacity Fig. However, such subassemblies subjected to monotonic or cyclic loading. As finite-element-analysis methods require complicated modeling shown in Fig. Furthermore, the analytical results pre- ments of the concrete and the reinforcing bars.

The simplified sented as the stress�strain relationships of materials are difficult stress�strain relationships for the concrete and reinforcing-bar el- ements were employed. E-mail: parkhg snu. So- Technology, , Yongcheon, Dongtan, Hwasung, Kyungi-do , phisticated stress�strain relationships of the concrete and South Korea. E-mail: macraian snu. Associate Editor: Dat Duthinh. Discussion open until March 1, clic behavior of the RC members that exhibit stiffness degrada- Separate discussions must be submitted for individual papers.

To tion and pinching. To predict the deformation capacity of the extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted members, failure modes, such as, the compressive softening of for review and possible publication on February 24, ; approved on the diagonal concrete strut in tension�compression and the buck- March 9, This paper is part of the Journal of Structural Engineer- ling and fracture of the reinforcing bars, should be identified.

A ing, Vol. Based on these results, the aspects of the nonlinear truss model that require improvement need to be studied. Basically, each element is modeled as a composite ele- ment of the concrete and the reinforcing bar. The concrete element is idealized as a truss element subjected to cyclic compression and tension. The cyclic stress�strain rela- tionship of the concrete element proposed in the present study is shown in Fig. The compressive Fig. Each figure shows the for tension stress�strain relationships at the initial and subsequent load cycles.

For walls and columns having longitudinal reinforcing bars in the web of the cross section, the longitudinal-web element LC is placed in the middle of the cross section. As shown in Fig. On the other hand, in the truss model, the compressive and tensile forces of the concrete element are assumed to develop at the location of the longitudinal-boundary element LE with a Fig. Cyclic stress�strain relationship of reinforcing-bar element specific area.

However, the the compressive zone. Cu can be calculated by using either sec- truss model using the axial force elements cannot describe the tional analysis or the equivalent stress block at the ultimate state shear resistance of the compression zone. In the present study, the shear force applied to an RC is defined as follows: member was assumed to be resisted entirely by the shear rein- forcement.

As shown in the cyclic loading, they are modeled only with the transverse Fig. The cross-sectional nal concrete elements are symmetrically arranged. According to Suda et al. The buckling of the reinforcing bars occurs after spalling Fig. Calculation of transverse tensile strain in diagonal element of the cover concrete. Generally, in a numerical analysis using separate models of concrete and reinforcing bars, the concrete and reinforcing-bar elements are assumed to act independently.

For this rea- son, under cyclic loading, the spalling of the cover concrete Modeling of Failure Mechanism occurs earlier than expected. The validity of Eq. In Specimen RV The truss models of the test specimens are also shown in with an asymmetric reinforcing-bar layout, the longitudinal Figs. In the truss models of No.

In the truss models of the bar elements are shown in Table 1. For the Fig. This result indicates that the NTM can the stress�strain relationship of confined concrete proposed by address the effects of various design parameters such as the shape Mander et al. The VACI the loading point. As shown in the figures, the cyclic behavior of was determined as the minimum of the nominal flexural strength the specimens varied according to the design parameters.

In and shear strength. The predicted load-carrying capacities agreed ior. Although B The energy-dissipation capacities were cal- sion. For comparison, the same maximum displacement was As shown in Figs.

The dicted maximum displacements were less than the test results, the NTM described well the trend of the inelastic responses according predicted value was used as the maximum displacement. For Fig. As shown in Table 2 and Figs. Discussion Table 2 presents the failure modes and the maximum displace- ments resulting from the tests and the NTM.

The failure modes As described previously, both walls and short beams with conven- predicted by the NTM were also marked in Figs. The av- erage ratio of the predicted maximum displacements to the test tional shear reinforcing-bar layouts failed due to web crushing. In results was 1. As the tensile reinforcement failed due to the crushing of the diagonal concrete crack width increases and the compression struts are separated by struts in the web.

As presented in Table 2, the NTM accurately the curved crack surfaces, the effective area of the compression predicted the web-crushing failure of the beams and walls with struts that can transfer the compression stresses decreases. For conventional shear reinforcing-bar layouts. The crushing of the diagonal thick and small panels. Therefore, the compression softening of concrete strut did not occur, because the diagonal reinforcing bars the concrete struts should be defined differently, depending on the and axial compressive force prevented excessive inclined web size and thickness of the panel subjected to shear.

As presented in Table 2, the NTM did not accurately In the NTM, the compression softening of the concrete struts predict the failure modes of bar buckling and fracture.

More was defined by Eqs. Originally, Eq. Ratioa NTM Exp. However, Eq. Based on the estimated the web-crushing strength of beams with relatively results of the numerical study, Eq.

For this reason, Eq. Since the stress�strain relationship of the softened concrete strut was not known, the uniaxial compres- sive stress�strain relationship of concrete in Eq. As shown in Figs. As shown in Bertero, V. However, TM2 underestimated the maxi- bar. If the stress Cervenka, V. Despite such disadvantages of mas Telford, London, As mentioned pre- 3� In the proposed beams with different reinforcing-bar layouts.

Therefore, the proposed truss model underestimates the load- Han, S. Modeling techniques that can address the Hibbit, Karlsson, and Sorensen, Inc. Hwang, S. Lee, J. Reinforced reversed cyclic loading. Each element was modeled as a composite behavior of prestressed concrete beams with web reinforcement.

A simplified cyclic Structural research series , Univ. To predict Studies, Urbana, Ill. The buckling of reinforcing bar in concrete columns. Short beams and walls with conventional shear reinforce- Skokie, Ill. In order to describe Okamura, H. Nonlinear analysis and constitu- the web crushing of beams with a relatively thick web, a tive models of reinforced concrete, Gihodo�Shuppan, Tokyo.

Park, H. Beams with diagonal shear reinforcement and columns failed Paulay, T. NTM did not accurately predict such failure modes. There- Popov, E. Ramm, E. Saenz, I. To, N. Earth- diagonal web reinforcing bar. Stevens, N. Tanaka, H. Vancouver, B. Muttoni2; and P. Gambarova3 Abstract: This paper presents the theoretical basis and the main results of an analytical model that describes the pre- and postyield response of bond in reinforced concrete, as well as its influence on the behavior of structural members.

The model is based on a number of reasonable assumptions that simplify the differential equation governing the phenomenon. In this way, a closed-form integration is feasible in certain cases, and relatively simple but accurate expressions can be worked out for the interface slip, the strain, and the stress in the reinforcement and the bond stress at the bar�concrete interface. The agreement between the available test data turns out to be quite satisfactory.

Consequently, the proposed model can be usefully adopted for studying the serviceability behavior, the ductility and the postyield response of a variety of reinforced-concrete members. Introduction reasonable assumptions that lead to the description of bond me- chanics in long bonded members by means of a first-order differ- Most engineering problems concerning structural concrete have to ential equation. This equation can be easily integrated for any do with bond, whose understanding and modeling is instrumental bond law, with reference to a wide range of practical applications.

The resulting The need for an analytical description of bond in the postyield laws are simple enough to be used in practical cases, and satis- range of the reinforcement has led to the development of several factorily fit the available test data.

More re- cently, a theory based on a rigid-plastic bond law has been pro- posed by Marti et al. Within this context, this paper summarizes the research activity of the This section describes the local response of bond considering two writers.

Reference is made to an axisymmetric concrete cyl- terms of bar slip or bar stress. However, the closed-form integra- inder reinforced with a single deformed bar, that is assumed to be tion is possible only in a limited number of cases. In this paper a well confined. E-mail: miguel. E-mail: relative steel-concrete slip can be considered constant in the aurelio.

E-mail: pietro. The response, see Fig. Associate Editor: Sashi K. Discussion open until terized by an ascending branch up to a certain relative slip where March 1, Separate discussions must be submitted for individual the force reaches its maximum, followed by a softening branch. The manuscript for this paper The similarity of the behavior in pull-out and push-in tests can was submitted for review and possible publication on February 1, ; be explained by the relatively low stresses and strains in the bar.

This paper is part of the Journal of Struc- Consequently, the response of the system is mainly controlled by tural Engineering, Vol. Deviations from this assumption occur in other cases as shown in Fig. However, the deviations for these members are usually lim- The qualitative slip distribution along the axis of an anchored bar ited as it will be shown later. To do this, Eq. To in- pull out, the previous bond laws are used, and a bilinear formu- troduce the influence of the longitudinal strains of the bar, the lation with constant strain hardening for the reinforcing bar is following bond coefficient is adopted: adopted, as sketched in Fig.

A good correlation with bar. Elastic Behavior of the Bar To study the response of a long anchored bar in the elastic do- main, Shima et al. All bars had a diameter of Fitting of the test results by Shima et al. Tests by Shima et al. With the proposed approach, this relationship can be obtained by eliminat- ing x from Eqs. In Fig. The square-root model correctly reproduces the evolution of the bond stress for the different values of the elastic modulus of the bar.

The rigid-plastic model provides a reasonable estimate of the mean value of the bond stress, but does not describe the actual bond-stress distribution. Elastoplastic Behavior of the Bar Shima et al. Further, as long as the bar remains in the elastic domain, the influence of this phenomenon can be neglected, as cracking at the end sections is very limited.

On the contrary, bond loss at the ends Analytical Model of a tie cannot be neglected after the yielding of the bar. Both the elastic plastic model. The distribution of the strains were loaded in four-point bending and presented a pure-bending along one-half of the tie is shown in Fig.

The square-root zone between the supports. The bond stress de- creases at the ends as indicated by the decreasing slope of the steel-strain diagrams. In general, the square-root model yields better results than the rigid-plastic model. Shima et al. Conclusions This paper is aimed at the analytical modeling of bond in long anchored bars and tension ties, with reference to the pre- and postyield behaviors of the steel.

This equation can be integrated in a closed form in several cases, and the response of the anchored bar is described by simple analytical expressions. Plots of the strains in the rebar of Specimen 4 by Shima et al. References Notation Alvarez, M. Bigaj, A. Kenel, A. Laurencet, P. Shima, H. Tokyo, chord model for structural concrete.

Thermou, Ph. Pantazopoulou, M. ASCE2; and A. Elnashai, F. The model considers the relative slip at the interface between the existing member and the jacket and establishes the mechanisms that are mobilized to resist this action, thereby supporting composite behavior.

An iterative step-by-step incremental algorithm was developed for calculating the overall flexural response curve. Consideration of frictional interlock and dowel action associated with sliding at the interfaces as well as the spacing and penetration of flexure-shear cracks are key aspects of the algorithm.

The proposed procedure was verified through comparison with published experimental data on RC jacketed members. Monolithic response modification factors related to strength and deformation indices were evaluated and the sensitivity of the model was assessed. Introduction various values have been reported for Ki, ranging from 0. For practical purposes, response pacity of the jacketed member, roughening of the interface in- indices of the jacketed members such as resistance and deforma- creases the energy absorption capacity, and a combination of the tion measures at yielding and ultimate are routinely obtained by two procedures improves stiffness.

The multipliers are venience, as the mechanics of composite action of jacketed re- referred to in the literature as monolithic factors, Ki.

A de- 1 tailed method for calculating these factors would be required in Dept. Sofias 12, Xanthi , Greece. E-mail: gthermou civil. From the available experimental evidence it appears 2 Professor, Dept. E-mail: pantaz civil. Hall Professor, Dept. Indeed, sliding failure at the interface limits the Environmental Engineering, Univ.

This paper presents a detailed procedure for estimating the E-mail: aelnash uiuc. Discussion open until March 1, The composite action that jacketed reinforced concrete members To develop in flexure greatly depends on the force transfer that oc- extend the closing date by one month, a written request must be filed with the ASCE Managing Editor.

The manuscript for this paper was submitted curs between the core and the jacket. Estimating strength and for review and possible publication on October 27, ; approved on deformation capacity of such members is a complex mechanics March 9, This paper is part of the Journal of Structural Engineer- problem that is hampered by the limited understanding of the ing, Vol.

Interface Shear Behavior Slip at the interface between the existing member and the jacket is explicitly modeled. The first two terms collectively represent the contribution of concrete as their dependence on critical design variables an analytical model they depend on the frictional resistance of the interface planes.

The significance The clamping stress represents any normal pressure, p, externally of jacket detailing on the resulting response and the associated applied on the interface, but also the clamping action of reinforce- values of the monolithic factors for strength and deformation ca- ment crossing the contact plane as illustrated in Fig.

From pacity is demonstrated and quantified through parametric studies equilibrium requirements it is shown and correlation of analytical estimates with test results. It is assumed that the existing member core is partially connected Shear transfer is affected by the roughness of the sliding plane, with the external jacket layer, so that the mechanisms of force by the characteristics of the reinforcement, by the compliance transfer at the interface are mobilized by relative slip of the two of concrete, and by the state of stress in the interface zone.

Dowel bodies. In analyzing the flexural behavior, the cross section of the action develops by three alternative mechanisms, namely, by di- upgraded member is divided into three layers. The two external rect shear and by kinking and flexure of the bars crossing the ones represent the contribution of the jacket, whereas the middle contact plane.

The difference in value at the interface, as follows: normal strain at the interface between layers accounts for the 1. Frictional resistance: The concrete contribution term in corresponding slip in the longitudinal direction; thus, only the Eq. To calculate the axial stress of the bars resultant between two adjacent cross sections. The procedure is crossing the interface, f s, the separation w between contact implemented in an iterative algorithm that employs dual-section surfaces as they slide overriding one another is considered analysis.

From the free body diagram shown in Fig. The crack spacing is es- given the slip magnitude, s. Using dual-section Eq. From basic mechan- interface strength that corresponds to the level of slip already ics the vertical shear stress, vd,i, is taken equal to the horizontal attained. Initially, interface slip is taken slip magnitude, si. The shear Deformation Estimates at Yield and Ultimate flow is calculated from dual-section analysis, using the estimated The cross section is considered to have attained a state of flexural flexural stresses.

Interface shear resistance is jd mobilized depending on the slip magnitude: interface shear resis- In Eq. Terms in Eq. The strain pro- bottom interfaces, s1u and s2u, as shown in Fig. It comprises the following steps: deformation indices of jacketed members are expected to be 1. In order to investigate the validity of the proposed analytical model for RC jacketed members published experimental data are used. It is noted that reinforcement slip owing to bond was included.

Details of the experimental program are outlined in Table 1 for all specimens considered such as geometric properties and rein- forcement details of the original as well as the jacketed elements. In the identification code adopted for the present comparative study the first character is either S or M corresponding to strengthened members with jacketing after cyclic loading or specimens built monolithically with a composite section to be used as controls, respectively.

The second character represents the treatment at the interface: r corresponds to roughened interface Fig. Flowchart of proposed algorithm achieved by chipping or sandblasting or other such methods, whereas s represents a smooth interface. The character l corresponds 2. The numeral in Eq. Calculate the shear stress at the upper and bottom interfaces, in Table 1.

Check cross-section equilibrium. The experimental curves plotted on the of the jacketed cross section; same figures represent the envelope of the recorded lateral load 7. Estimate the moment resultant M n. Calculations stop when the capacity of the shear in reproducing the trends of member behavior even if interface interface is exhausted. The analytical model provides a lower bound of the response of the jacketed members and it may generally be considered conservative, while matching well the experimental Experimental Validation values.

At low deformation levels response curves obtained by the analytical approach and by the monolithic approach almost coin- Although RC jacketing is one of the most commonly applied cide. This is expected as long as crack formation is at an early rehabilitation methods worldwide, a limited number of experi- stage. Clearly, the analytical result is very close to its experi- mental counterpart in the case of specimens MsN-7 and SsNpd-5 Fig.

The experimental curve rep- Bousias et al. The response of unit SsNw is very close to the response as to establish the sensitivity of the monolithic factors to the of the monolithic approach, although slip at the interface modifies important design and model variables. Note that these factors the response somewhat, as shown by the analytical curve.

A more sensitive model that could variables of monolithic members with identical cross section, on describe in more detail the interface shear behavior would provide the premise that the latter quantities are easily established from better results. In general, a softer response than the experimental conventional flexural analysis.

Interface be- havior requires further calibration, and this would have been done if a critical mass of experiments were available. However, even as Parameters of Study things stand, by explicitly accounting for this aspect in calculating A sensitivity analysis of monolithic factors is conducted in this section through a detailed evaluation of two reference cases.

The core of the composite member is the existing member, represen- tative of former construction practices. The arrows indicate was reduced from 4. This indicates that 1. The dominated ones. The results of the parametric study are presented in terms of the monolithic factor values both for flexural strength and for deformation capacities.

Role of Characteristics of Jacket The direct effect induced by any change in the design character- istics of the jacket is depicted for both the yield and the ultimate stage in Fig. The circular mark in Fig. Influence of jacket longitudinal reinforcement on monolithic Fig. From the results of was given by Eq.

Considering that slip at the upper and bottom An algorithm for calculating the monotonic response of rein- interfaces contributes to lateral drift, the reduced value of curva- forced concrete jacketed members is presented. The weak link controlling deformations in this problem is the interface. The capacity of the weakest link is evaluated and checked in every step, to make sure it is not exceeded by the Sensitivity of Analytical Model demand.

The shear demand at the interface is controlled by the flexural stresses on the cross section and by the spacing of cracks The proposed analytical model is primarily sensitive to param- in the longitudinal direction, whereas the shear capacity is a func- eters that affect the estimation of crack spacing and the shear tion of slip. The shear stress slip relationship for the contact sur- strength of the contact interfaces.

Each of these variables has a faces and the definition of crack spacing play a key role in the distinct influence on the computational procedure; however, algorithm. Analytical results show that the model can reproduce selection of the shear interface model is fundamental. A para- A brief parametric investigation was conducted in order to metric study was conducted and the dependence of various mono- explore the sensitivity of the model to the primary variables.

The square cross section used in the preceding as Case 1 is used as a point of reference. Longitudinal jacket reinforcement ratio between 0. No axial load was applied on 0. The monolithic factors of curvature and concrete. To model unfavor- 0. Bass, R. Bett, B. Seismic design of reinforced of strengthened and repaired r. Rodriguez, M. Tassios, T. Vandoros, K. Ersoy, U. Part 1. Gomes, A. Concrete Res. Triangular units are grouped into rectangular zones mimicking brick units with surrounding mortar joints.

Fracture is captured through a constitutive softening-fracture law at the boundary interface nodes. The mortar joint, which is a plane of weakness, can be modeled as an interface of zero thickness or of a given thickness.

The model is ideally suited to the modeling of fracture in masonry because fracture usually runs along a horizontal or vertical joint in the mortar or is approximately vertical in the brick unit.

The inelastic failure properties are divided into those for the mortar joints and those for fracture within the brick units. The inelastic failure surface is modeled using a Mohr�Coulomb failure surface with a tension cut-off. Examples which include: Direct tension, microshear, and three-point bending of masonry panels are used to verify the formulation. The approach used a , ; Sutcliffe et al.

The programming algorithm to obtain equilibrium solutions to a non- fracturing process in masonry is complex because masonry is the holonomic rate formulation. When a bifurcation was encountered, composite of two brittle materials, the brick unit and the mortar the equilibrium path with the minimum incremental external work joint, which can have very different material properties.

The constitutive law was a single The weakness element in a masonry panel is typically the branch softening law written in terms of forces and displace- mortar joints but fracture can also occur in the brick units.

Be- ments. The advantages of this formulation were that, as with the cause the joints follow a pattern of crisscrossing horizontal and discrete crack models, there was no length scale required.

The formulation of Attard tancy induced by shear. Giambanco et al. The posi- joints. The formulation can be classified as discrete. The material within Associate Professor, School of Civil and Environmental Engineering, the triangular unit remains linear elastic if the inelastic constitu- Univ. E-mail: m. Masonry is 2 Professor, Dept. E-mail: modeled by combining the triangle units to form a brick with the nappi univ.

E-mail: f. Associate Editor: Khalid M. Discussion open until assigned the inelastic constitutive properties of the mortar. The March 1, Separate discussions must be submitted for individual interior interfaces of the brick have the inelastic constitutive prop- papers.

To extend the closing date by one month, a written request must erties of the brick. The manuscript for this paper was submitted for review and possible publication on July 22, ; modeled.

This paper is part of the Journal of Struc- unit. For the nodal inelastic failure surface shown in Fig. The inelastic the traction along the interface may not be uniform. Note that Qsy represents a combination of shear and cap is considered in this paper. The flow rule is nonassociated some tension depending on the friction angle. It is used to define when the friction and dilatancy angles are different. For a com- the Mohr�Coulomb failure surface. Elastic unload- ing is allowed from the descending branch.

No previ- sions for cracks coming back into contact have been made in this work. The critical crack opening displacement used with the single branch softening constitutive law is approximated from the Fig.

Inelastic failure is activated if the structure interface generalized force vector Q intersects the assembled structure inelastic failure surface. The following constraints must also Mohr�Coulomb plane. At each event, a set of active multi- of the normal interface force and the interface shear capacity.

The linear complementarity tropic manner. The evolution of the interface inelastic failure sur- problem, Eq. Either an enumerative proce- dependent softening behavior in rate or finite incremental form dure to solve the LCP is used, as described in Bolzon et al. Only a brief description will be given here.

For ployed or a single event by event strategy as described below the complete structure such as a masonry panel or wall, the inter- could be employed.

When multiple solutions are detected, the face generalized forces are collected into a structure generalized equilibrium solution which provides the minimum increment in force vector Q. Similarly, a structure hardening matrix H, the external work should be taken as the critical solution.

Masonry detail for infinitely long wall under tensile loading Poisson ratio � 0. If one included behavior. When several locations within a Figs. Tensile inelastic structure simultaneously reach inelastic failure, the minimum failure occurred along the vertical mortar joints followed by shear work would be done if only one softens and the rest elastically inelastic failure along the horizontal joint.

For the elastic displacements of the final failure mechanism. The large problems the single event by event strategy is adopted here.

Initially, the inelastic failure zone Three examples are presented which demonstrate the application is activated in a symmetric pattern with tensile inelastic failure of the proposed model for the analysis of fracture in masonry. The along the two vertical mortar interfaces.

One of the two interfaces first example deals with tension parallel to a bed joint but in- then dominates with unloading from the other. The behavior is similar to that identified in a two notch tensile test second example explores the capability of the model to handle when the loading platens are allowed to rotate.

The tensile crack shear under different confining pressures. The last example looks in one of the vertical mortar joints then propagates through the at results for the three point bending of a masonry panel with vertical interface until it reaches the horizontal interface and the either weak or strong mortar and demonstrates the ability of the cracks open reaching the critical crack opening displacement.

Tensile cracking then propagates through the other vertical inter- face. Once both vertical interfaces have cracks opening freely, shear inelastic failure is activated along the horizontal interface. Tensile Behavior Parallel to Bed Joint There are three peaks in the stress versus displacement results. The third peak is associ- panel detail used to model an infinitely large wall under tension as ated with inelastic failure along the entire horizontal interface.

The axial loading is parallel to the bed joint. The results using the proposed algorithm for a dila- the mesh used for the present formulation with each brick unit tancy angle of 0 and The bed stated earlier, several of the material properties for the brick units joints were approximately 2 mm thick, whereas the head joints were scaled from the mortar properties. The weakest element of were approximately 3 mm thick.

The mesh shown in Fig. The material proper- versus displacement results and the ultimate failure mode, respec- ties for the mortar and brick unit are listed in Table 1. Only the tively.

No shear plane inelastic failure was acti- using the ratio of the brick to mortar tensile strength. Two cases vated. The four peaks in the stress versus displacement results have been investigated. Case A restricted the potential inelastic correspond to failure along the vertical interfaces. A vertical distributed confining force was applied to the rigid top boundary. The masonry specimen had initial confining stresses of 0. Forces were applied at one end of the rigid element which produced a idealized state of pure shear at the midsection of horizontal mortar interface.

Inelastic behavior was only permitted along the mortar interface. The brick units measured mm in length, 50 mm in height, and mm in thickness. The mortar bed was approximately 15 mm thick. Case B�comparison of stress versus displacement Fig. The main objective was to trace the average shear mortar bond stress as a function of the shear dis- placement across the mortar interface.

The test rig consist of ac- tuators to apply the normal confining stress and actuators which loaded the brick unit with a combination of bending and shear producing pure shear on the mortar joint. The top and bottom test loading frames were modeled using rigid elements along the top horizontal boundary and by Fig. Simulation model for the microshear test of van der Pluijm Fig. The material properties for the because of the use of a single branch softening constitutive law.

An average shear stress at the ure surface and are softening at the same rate, hence on a struc- horizontal mortar interface was calculated and plotted against an tural level the softening behavior of the model would appear average shear displacement based on the displacements at the linear.

The present model could be improved by using a bilinear gauge points indicated in Fig. As well, the present model uses a con- For the numerical model, as the load was increased, a zone of stant friction angle and dilatancy angle. The model may give a inelastic shear failure spread throughout the horizontal layers of better comparison with the experimental results if the normality the mesh representing the mortar joint. As the inelastic shear zone and dilatancy matrices defined in Eq.

At the peak load, inelastic shear failure had activated the interface of the top layer of the mortar joint. The critical shear displace- Three-Point Bending of a Masonry Panel ment for the interface nodes was reached almost simultaneously because all nodes essentially had the same shear displacement. At Guinea et al. The panels were constructed shows the scaled deformation mode at failure with the top layer of using nine courses of ten brick units with a total height of ap- the mortar being sheared and expanding out as dilatancy was no proximately mm.

The dimensions of the panels are shown in hindered. A midspan notch of approximately 39 mm was sawn. Al- and finally through a second mortar joint. The top of the notch though the proposed model compares reasonably with van der was below a brick unit. This can partly be explained data including the splitting tensile strength and compression Table 2. Table 3 lists the material properties used in the simu- lation here. In Table 3, Mortar A is based on the mortar used by Guinea et al.

The mortar and brick units used by Guinea Fig. Comparisons with the three-point bending test results of et al. The fracture was primarily Mode 1. The mortar interface was modeled throughout the loading history. During the simulation for Mortar with zero thickness. The elastic modulus for the composite was Types B and C a large number of mortar joints became inelastic at selected from a back fit to the experimental results and was taken some stage during the loading but unloaded as the damage zone as 18, MPa.

A comparison of the simulation for Mortar Type progressed through the panel. Before the fracture penetrated the A with the test results of Panel P4 of Guinea et al. The comparison shows generally the same lin- sliding on the horizontal mortar joint above and below the brick ear and postpeak response although the simulation did not have unit, as well as the mortar joint on either side of the brick unit.

The load deflection result for track branching and interacting cracks as well as shear failure in Mortar Type B has several peaks along the postpeak path. The the joints, the simulation was run with two further mortar defini- secondary hardening in the postpeak path are generally associated tions. Mortar C was the same as Mortar B but with reduced shear strength. Table 3 gives the material properties for the mortars designated as Mortar B and Mortar C.

Because the brick unit has a much higher Table 3. Wittmann, ed. Softening from the secondary peaks are generally tions in quasi-brittle fracture computations. The � Giambanco, G. Methods Appl. The load deflection response for Mortar Type C � Rots, and Spanje, eds.

The numerical approach. The present formula- plasticity with interacting inelastic failure planes. The cracking and Mate- Nappi, A. A Mohr�Coulomb failure surface with a tension cutoff has Pacific Conf.

The present formulation uses a constant friction ics for the Next Millennium, Vol. Wang, K. Lee, and K. The 81� Nappi, A.

The advantages of the present procedure is that inelastic Page, A. Page, A. Masonry Constr. Sutcliffe, D. The writers gratefully acknowledge the financial support of the Tin-Loi, F. Bolzon, G. I: Analytical Development Robert B. The PZ-MN is configured directly for optimal seismic performance through a casting process. The PZ-MN dissipates energy through stable yielding of the panel zone. This objective is accomplished by mitigating the effects of panel zone distortion on surrounding members and connections.

Field welds are removed from critical cross sections and demands are redirected in noncritical paths. A cast piece easily accommodates the geometries and features to meet this objective.

The PZ-MN was developed through a comprehensive analytical research program and verified through full-scale experimentation. This paper describes the analytical development stage. Investigation of trial configurations, key parameters, and enhancements resulted in a prototype design for the PZ-MN.

The PZ-MN prototype shows the potential for excellent seismic performance, including under the combined effects of lateral and gravity load. This performance is experimentally verified in a companion paper. Introduction quirements are considered as a first step in determining the modu- lar node configuration. The the needed versatility in design. Thus, the modular nodes are cre- PZ-MN is one of several modular nodes and connectors under ated through a casting process.

The impetus for developing The PZ-MN was developed through a comprehensive analyti- these new forms is the discovered susceptibility to fracture of cal and experimental research program.

This paper focuses on the welded beam-to-column connections in steel special moment analytical development stage. These structures rely chosen for prototype development. Analytical investigation of on the strength, stiffness, and ductility of moment connections at trial configurations under lateral load resulted in a prototype de- the beam-to-column joints to create an efficient lateral-load resist- sign.

However, more than SMFs load effects. The in terms of ductility and energy dissipation. The field welded to the beam. The column and beam interfaces are modular node approach attempts to address these recommenda- modular, thus a single PZ-MN is compatible with an assortment tions directly through aspects of modular construction and of sections of the same depth. A major benefit of this approach is alternative manufacturing processes.

Seismic performance re- the elimination of a field weld from the beam�column interface, which is a potential source of brittle fracture in traditional con- 1 Associate Professor, Dept. Large shear forces develop in the panel zone under lateral Associate Editor: Sherif El-Tawil. To accomplish this design, distortion at the beam flange- 1, To column flange interface must be mitigated in order to obviate a extend the closing date by one month, a written request must be filed with the ASCE Managing Editor.

In com- bination, these features will be shown to create an extremely ef- Panel Zone Behavior ficient and ductile energy dissipating detail. Background Panel zone yielding possesses good hysteretic behavior, a greater strain hardening slope, and less likelihood of local buckling when The development of the PZ-MN makes use of a large body of compared to other ductile mechanisms such as beam plastic hinge research on welded steel moment connections, summarized here.

The weld access hole detail produces severe et al. Evaluation of pre-Northridge designs has indicated strain concentrations at the toe of the hole.

In these regions, low- that typical practice may have led to panel zones that were weaker cycle fatigue can initiate ductile tearing of the beam flanges.

As is typical of SMFs, the seismic design of the L. In comparing these ca- on response to lateral load alone. Once the PZ-MN prototype was pacities directly, plastic hinge locations and column axial effects developed, full-load performance was evaluated using the gravity are ignored.

It is important to note that though strong column- load conditions shown in Fig. Thus, the lower stiff- The PZ-MN prototype design strength was aligned to the experi- ness associated with a weak panel zone is somewhat offset by mental laboratory actuating capacity for subsequent full-scale leveraging of material strengths.

The PZ-MN contribution to experimental verification. The Fig. Gravity yield strength factor and 0. This calculation produces 0.

A configurations accurately with respect to many important mea- sufficiently large cruciform is seen to eliminate kinking, as shown sures. For this, the PZ-MN state was evaluated at a dissipated in the panel zone. Once panel zone energy dissipation is more gradual for the PZ-MN due the prototype design was finalized, cyclic analyses were per- to the presence of the cruciforms.

For the tradi- Fig. The relationship between beam flange shear and panel zone strength is shown in Fig. The panel zone deformation from a weak panel zone, acting against Fig. In contrast, for the this region constrains panel zone deformation. A viable solution is PZ-MN with the large cruciforms, the kinking does not increase to eliminate the PZ-MN beam link web and size the beam link and instead remains at significantly lower values.

This is the configuration selected, which also has the of the column flange curvature deemed tolerable in design. An architectural advantage of allowing a pass through for mechanical allowable value of 0. Accordingly, the conduits. This point becomes more significant when welds to the framing beam.

This condition compromises the design objective of the PZ-MN. The link region dimensions are determined through a capacity Fig. A free body of the Safety Administration. Without these measures, analyses indi- RLS region is shown in the inset of Fig.

In summary, the PZ-MN configuration provides the potential where for highly ductile and repeatable response under lateral load. The needed features are created rather effortlessly in castings, whereas 1 2 fabrication would be quite expensive and involve welded joints.

The strain demands in the RLS and beam weld regions. The shown in Fig. These features evaluated to 0. The flange tab extends from the beam model. The tab also provides two points of cause inflection points do not occur at beam midspan. Gravity Fig. Lateral load is then applied through displacement mand. A straightforward web connector geometry casting redesign measured.

Such mea- sures seem necessary for beam gravity shear in excess of kN. The RLS strains at 0. Panel zone characteristics are tabulated in Table 4 and indicate gradual decline in all values with column Combined Effect under Maximum Gravity axial load. It was concluded therefore that As can be seen, very large column axial loads have a notice- the effects could be considered separately as presented. The PZ-MN has shown promise for use as a special energy- Conclusions dissipating detail in steel moment frames in high seismic zones by exhibiting the potential for extremely high ductility.

A PZ-MN prototype was developed and evalu- presence of typical perimeter moment frame gravity load condi- ated through an analytical program. The following relationships tions. Englekirk, R. Industry Partners Varicast, ings. The writers are grateful for this support. Any opinions, Washington, D. Fleischman, R. Schneider, S. Blue sions for structural steel buildings, Chicago. Seismic provi- Stojadinovic, B.

Bertero, V. Part 1: Prototype development. El-Tawil, S. Nanbu earthquake. Fleischman1; Nathan J. The PZ-MN dissipates energy through stable yielding of its panel zone, an objective accomplished by mitigating the effects of panel zone distortion on the surrounding members. The PZ-MN is configured directly for this purpose through a casting process. This paper presents experimental verification of the PZ-MN prototype. This process relied heavily on interaction with industry partners to create a castable and constructible shape.

The PZ-MN prototype exhibited remarkable performance, greatly exceeding qualifying drift angles and possessing exceptional hysteretic characteristics. Using models based on these characteris- tics, frame performance is evaluated.

Design guidelines are given on the basis of the analytical and experimental results. Introduction ing. The PZ-MN design intent is to dissipate the majority of Steel Castings seismic energy through stable yielding of the panel zone. Accord- ingly, the PZ-MN employs a weak panel zone relative to other Steel castings find widespread use as structural components in components. To accomplish this design, distortion at the beam heavy industry applications that are safety critical, and perfor- flange�column flange interface must be mitigated.

Similar material to rolled steel can be cast, how- directly configuring the piece for seismic performance. To assure a viable proto- piece shape, size and wall thickness. The challenge to the foundry type, emerging designs were regularly evaluated by foundry in- industry partners was to meet the structural shape and perfor- dustry partners for castability and modified where appropriate.

The PZ-MN prototypes exhibited remarkable performance, The geometries desirable for the modular nodes such as thin- greatly exceeding qualifying drift angles and possessing an excel- to-thick transitions or isolated flanges require the careful place- lent hysteretic characteristic including exceptional strain harden- ment of a number of gravity-driven liquid feed metal reservoirs, termed risers, to compensate volumetric contraction thus avoiding 1 Associate Professor, Dept.

Traditionally, this quality control has Univ. For this AZ