The only difference in these two methods is the technique used. Capacitydemanddiagram methods for estimating seismic. Investigation of effects of capacity spectrum method on performance evaluation of multistory buildings according to the iraqi seismic code requirements. Freeman 1998 development and use of capacity spectrum. Target displacement two approaches to calculate target displacement.
The pushover analysis, explained in its simplicity alacero. Capacitydemanddiagrammethods for estimating seismic. An approach of seismic design for sheet pile retaining. The underlying idea is to utilize inelastic response history analysis of sdof systems represented by bilinear force deformation. Evaluation of capacity spectrum method for estimate of. The convergence analysis of the capacity spectrum method in atc 40 is studied by using the theory of chaotic dynamics. Capacity spectrum method detailed in atc 40 and as alternate method in fema273. Volume 3, issue 12, june 2014 case study of rc slab bridge. Also the need for empiricallydetermined coefficients e. Contrary to other publications where investigations on static pushover methods are carried out assuming one or more. Evaluation of asce41, atc40 and n2 static pushover. Lateral load distribution factor for modal pushover analysis. Therefore, focusing on laterally loaded stabilizing sheet pile wall, which belongs to flexible cantilever. Seismic evaluation and retrofit of concrete buildings.
Application of capacity spectrum method based on atc 40. In the paper, capacity spectrum methodone of the methods of seismic design are discussed. The local concrete members that comprise the major structural elements of the. In order to calculate the target displacement or performance point, different methods such as capacity spectrum method csm in atc 40 1 and coefficient method in fema356 2 were introduced. Seismic assessment of rc building according to atc 40. The lateral force distribution for pushover analysis and conversion of these results to. To evaluate the performance of frame building under future expected earthquakes, non linear static pushover analysis was conducted. Capacity of the structure was obtained from pushover analysis. The accuracy of the capacity spectrum method csm depends on the precise estimation of equivalent period and damping ratio as well as the modification of the demand spectrum. Both of these methods depend on the lateral loaddeformation variation obtained by using the nonlinear static analysis under the gravity loading and idealized lateral loading due to the seismic action. One version ofthe improved method is graphically similar to atc 40 procedure a whereas a second version is graphically similar to atc 40 procedure b. The atc40 procedure b always gives a unique value ofdeformation, the same as that determined by procedure a ifit.
The spo methods chosen are the atc 40 capacity spectrum method, the displacement coefficient method of asce41 and the accelerationdisplacement version of the n2 method that has been recently adopted in eurocode 8 2004. Recently, much work has been done to develop and evaluate simplified methods for estimating peak deformation of inelastic systems, which has led to the \capacity spectrum method detailed in the atc 40 procedures a, b and c 1 and fema274 2 reports, as well as the \coefficient method outlined in the fema356 3 guidelines and. The other is the capacity spectrum method csm of atc 40, where the load. Investigation of effects of capacity spectrum method on. Summary and application example this document records in detail an effort to assess current nonlinear static procedures nsps given in fema 356 and atc 40 for the seismic analysis and. The most basic inelastic analysis method is the complete nonlinear time history analysis, which at this time is considered overly complex and impractical for general use. This method gives the deformation value consistent with the selected inelastic design spectrum, while retaining the attraction of graphical implementation of the atc 40 methods. The capacity spectrum method is one of the most established and widely accepted displacement based seismic design method which is used for performance based seismic design. Capacity spectrum method csm has been conveniently used for determined maximum roof displacement using both demand spectrum and capacity curve of equivalent single degree of freedom sdof system for evaluating the seismic performance of buildings.
Taiwan summary in order to account for the nonlinear behavior of structures via nonlinear static procedure, the capacity spectrum method has been adopted by atc. As the forefront of structural design method, capacity spectrum method can be applied conveniently, and through this method, deformation demand of structure can be considered. Variability and accuracy of target displacement from. The performance point of all the examined structures is estimated through the capacity spectrum method atc 40 and. However, based on previous researches, the observed results of applying these methods for identical structures were dissimilar. Another example is the n2 method where n stands for. The most general nonlinear static procedures are capacity spectrum method, as described in atc 4019961, and displace coefficient method, as described in fema 27319972 and. This procedure is a graphical approach to compare the capacity of a structure with the demand of earthquake ground motion on the structure. Some of the concepts officially incorporated in design guidelines include capacity spectrum method csm and displacement coefficient method dcm as adopted in atc 40 and asce41, n2 method as proposed in eurocode 8, and equivalent linearization method elm and displacement modification method dmm as presented in fema 440. Investigation of effects of capacity spectrum method on performance evaluation of multistory buildings according to the iraqi seismic code requirements doi. Plot the capacity diagram and 5%damped elastic demand diagram. Bnbc 1993 response spectrum was converted into adrs format.
Request pdf an improved capacity spectrum method for atc. The capacity spectrum method csm the capacity spectrum method csm is a nonlinear static analysis method, which compares the global forcedisplacement capacity curve of a structure with a earthquake response spectrum in a graphical shape freeman, 1998, badoux, 1998. The later procedure is used also in atc 40 as an alternative method, which is called the displacement coefficient method. Application of inelastic design spectrum to capacity. This method gives the defonnation value consistent with the selected inelastic design spectrum. However, there is no research for the seismic application in the structure of sheet pile retaining wall to report. Comparison of seismic demands determined by nonlinear. A nonlinear analysis method for performance based seismic. Topics include performance objectives, seismic hazard, determination of deficiencies, retrofit strategies, quality assurance procedures, nonlinear static analysis using the capacity spectrum method, modeling recommendations, foundation effects, and. The cm utilizes a displacement modification procedure in which the target displacement is computed by modifying. Capacity spectrum demand analysis based on proposed. Development and application of an advanced capacity. In this paper, the csm provided in atc 40 for estimating the peak inelastic responses is evaluated. Comparative study of nonlinear static and timehistory.
An improved capacity spectrum method for atca40 wiley online. One version of the improved method is graphically similar to atc 40 procedure a whereas a second version is graphically similar to atc 40 procedure b. Capacity spectrum method csm or displacement coefficient method dcm, such as in fema 273 1997, atc 40 1997, fema 356 2000, eurocode 8 2004, italian building code 2008, fema440 atc55, 2005, ascesei 4106 standard 2005. Single degreeoffreedom sdof system approach is used in determination of demands in nsps recommended in atc 40 and fema 356, which is called as capacity spectrum method csm and displacement coefficient method dcm, respectively. Pdf application of capacity spectrum method based on atc 40. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Spectrum method csm of atc40, where the load is incremented and. The atc 40 document comprises a practical guide to the entire evaluation and retrofit process. The nonlinear static procedure in these documents, based on the capacity spectrum method, involves several approximations. This video introduce a brief summary to the procedures of pushover analysis and capacity spectrum method.
Atc 40 seismic evaluation and retrofit of concrete buildings volume 1 by applied technology council 555 twin dolphin drive, suite 550 redwood city, california 94065 funded by seismic safety commission state of california products 1. In general, applying displacement rather than force loading in pushover procedures would be the most. Seismic assessment of rc building according to atc 40, fema 356 and fema 440. In this paper seismic capacity of structure to resist earthquake force was estimated by the capacity spectrum method. In reality the underpinnings of the current procedure are obscure.
Seismic evaluation of asymmetric wall systems using a. Estimate deformation demand di and determine ai from the capacity spectrum. The capacity spectrum method was first developed by freeman 3 and then this method was modified by fajfar in 1999 2. The atc 40 and fema274 documents contain simplified nonlinear analysis procedures to determine the displacement demand imposed on a building expected to deform inelastically. Method dcm of fema 356, where a target displacement is calculated to which the structure is pushed. Atc 40 report published by applied technology council identifies three capacity spectrum procedures a, b and c for determination of performance point. Ppt pushover analysis powerpoint presentation free to. The capacity spectrum method csm has gained considerable popularity amongst pushover users since its introduction in 1975 by freeman and collaborators. Chopra and goel12 14 found some flows in csm version of atc 40. Capacity spectrum method atc 40 in this method the maximum inelastic deformation of a nonlinear sdof system can be approximated from the. Fema 356 and atc40 for the seismic analysis and evaluation of structures.
The inelastic design spectrum is also introduced in this article and the results obtained by using atc 40 capacity spectrum method and capacity method based on inelastic demand, spectrum are. In order to account for the nonlinear behavior of structures via nonlinear static procedure, the capacity spectrum method has been adopted by atc40 for. Atc40 seismic evaluation and retrofit of concrete buildings. Volume 3, issue 12, june 2014 314 abstract after 2001 gujarat earthquake and 2005 kashmir earthquake, there is a nationwide attention to the seismic. The capacity spectrum method csm, a performancebased seismic analysis technique, can be. The advanced csm proposed in this section aims to overcome the difficulties encountered in nonlinear static analysis and provide better estimates of structural response. The alternative capacityspectrum method of atc40 is. Capacityspectrum method of atc 40 is a strength and a weakness. Pushover analysis solution schemes problem of degradation of strength. Summary of research on inelastic analysis procedures. A nonlinear static analysis procedure that provides a graphical representation of the expected seismic performance of the existing or retrofitted structure by the intersection of the structures capacity spectrum with a glossary components.
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