Lateral load distribution factor for modal pushover analysis. Chopra and goel12 14 found some flows in csm version of atc 40. Estimate deformation demand di and determine ai from the capacity spectrum. Contrary to other publications where investigations on static pushover methods are carried out assuming one or more. Atc40 seismic evaluation and retrofit of concrete buildings. This video introduce a brief summary to the procedures of pushover analysis and capacity spectrum method. The performance point of all the examined structures is estimated through the capacity spectrum method atc 40 and. In this paper, the csm provided in atc 40 for estimating the peak inelastic responses is evaluated. The advanced csm proposed in this section aims to overcome the difficulties encountered in nonlinear static analysis and provide better estimates of structural response. Eurocode 8 en 19981, 2003 also follows more or less the same approach.
Seismic assessment of rc building according to atc 40. Seismic evaluation of asymmetric wall systems using a. The atc 40 and fema274 documents contain simplified nonlinear analysis procedures to determine the displacement demand imposed on a building expected to deform inelastically. Spectrum method csm of atc40, where the load is incremented and. The later procedure is used also in atc 40 as an alternative method, which is called the displacement coefficient method. Freeman 1998 development and use of capacity spectrum. 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. 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. 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. Evaluation of asce41, atc40 and n2 static pushover. Atc 40 report published by applied technology council identifies three capacity spectrum procedures a, b and c for determination of performance point. The two widely used procedures to estimate the target displacement in the nsp are. Fema 356 and atc40 for the seismic analysis and evaluation of structures.
Evaluation of capacity spectrum method for estimate of. Pdf application of capacity spectrum method based on atc 40. Capacityspectrum method of atc 40 is a strength and a weakness. Application of inelastic design spectrum to capacity. However, there is no research for the seismic application in the structure of sheet pile retaining wall to report. 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. The local concrete members that comprise the major structural elements of the. 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. In reality the underpinnings of the current procedure are obscure. 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. Therefore, focusing on laterally loaded stabilizing sheet pile wall, which belongs to flexible cantilever.
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. An improved capacity spectrum method for atca40 wiley online. The capacity spectrum method csm has gained considerable popularity amongst pushover users since its introduction in 1975 by freeman and collaborators. The alternative capacityspectrum method of atc40 is. In this paper seismic capacity of structure to resist earthquake force was estimated by the capacity spectrum method. Investigation of effects of capacity spectrum method on.
However, based on previous researches, the observed results of applying these methods for identical structures were dissimilar. In the paper, capacity spectrum methodone of the methods of seismic design are discussed. The atc 40 document comprises a practical guide to the entire evaluation and retrofit process. 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.
The nonlinear static procedure in these documents, based on the capacity spectrum method, involves several approximations. Capacitydemanddiagrammethods for estimating seismic. Variability and accuracy of target displacement from. Ppt pushover analysis powerpoint presentation free to. The lateral force distribution for pushover analysis and conversion of these results to. The underlying idea is to utilize inelastic response history analysis of sdof systems represented by bilinear force deformation. Investigation of effects of capacity spectrum method on performance evaluation of multistory buildings according to the iraqi seismic code requirements. Capacitydemanddiagram methods for estimating seismic. Application of capacity spectrum method based on atc 40.
Target displacement two approaches to calculate target displacement. 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. Seismic evaluation of asymmetric wall systems using. 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. The other is the capacity spectrum method csm of atc 40, where the load. In order to account for the nonlinear behavior of structures via nonlinear static procedure, the capacity spectrum method has been adopted by atc40 for. The convergence analysis of the capacity spectrum method in atc 40 is studied by using the theory of chaotic dynamics. Method dcm of fema 356, where a target displacement is calculated to which the structure is pushed. The only difference in these two methods is the technique used. 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. To evaluate the performance of frame building under future expected earthquakes, non linear static pushover analysis was conducted.
Seismic evaluation and retrofit of concrete buildings. 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. Capacity spectrum method atc 40 in this method the maximum inelastic deformation of a nonlinear sdof system can be approximated from the. 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. Another example is the n2 method where n stands for. Capacity spectrum demand analysis based on proposed. 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 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. 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. This procedure is a graphical approach to compare the capacity of a structure with the demand of earthquake ground motion on the structure. Capacity spectrum method detailed in atc 40 and as alternate method in fema273. The cm utilizes a displacement modification procedure in which the target displacement is computed by modifying.
Comparative study of nonlinear static and timehistory. 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. In general, applying displacement rather than force loading in pushover procedures would be the most. 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. 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. 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. Citeseerx document details isaac councill, lee giles, pradeep teregowda. The pushover analysis, explained in its simplicity alacero. 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. A nonlinear analysis method for performance based seismic.
This method gives the defonnation value consistent with the selected inelastic design spectrum. Request pdf an improved capacity spectrum method for atc. The capacity spectrum method was first developed by freeman 3 and then this method was modified by fajfar in 1999 2. 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. An approach of seismic design for sheet pile retaining. Plot the capacity diagram and 5%damped elastic demand diagram. Bnbc 1993 response spectrum was converted into adrs format. The capacity spectrum method csm, a performancebased seismic analysis technique, can be. Investigation of effects of capacity spectrum method on performance evaluation of multistory buildings according to the iraqi seismic code requirements doi. Capacity of the structure was obtained from pushover analysis.
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