The Extended Adaptive Capacity Spectrum Method for the Seismic Assessment of Plan-Asymmetric Buildings

Abstract

The use of nonlinear static procedures (NSPs) on the seismic assessment of real existing plan-irregular structures has so far been studied by a limited number of authors. This fact limits the application of such methods to assess current existing structures, the majority of which are irregular in plan. An extended version of the adaptive capacity spectrum method (ACSM) for the seismic assessment of plan-irregular buildings is presented in this paper. The novelty of this proposal is to comprise the most accurate features of commonly used NSPs in order to overcome the problems that subsist in three-dimensional pushover analyses. The accuracy of the procedure is tested in three plan-irregular real buildings. The results are compared with the capacity spectrum method (CSM) with the features proposed in FEMA 440, with the extended N2 method for plan-asymmetric structures, with the adaptive capacity spectrum method (ACSM) and with the most exact nonlinear dynamic analyses. Several seismic intensities are tested, in order to evaluate the performance of the procedure in different stages of structural inelasticity.

An overview of modern seismic analyses with different ways of damping introduction

“…Kod NICSM se direktno određuje nivo ciljnog pomeranja, bez iteracija, bazirajući se na rešenjima ekvivalentnih linearnih metoda [55]. Takođe, ovoj grupi pripadaju ICSM [54], [33] i ACSM [11], [10] koje su zapravo poboljšane verzije postojeće CSM i koje primenjuju statistički optimizovane linearizovane parametre i adaptivne algoritme za određivanje nivoa ciljnog pomeranja. Primenom DCM sprovodi se samo TDA, koristeći princip multiplikacije grupe koeficijenata kojima se uzima u obzir uticaj različitih faktora ponašanja konstrukcija.…”

“…NICSM directly determines the level of target displacement, without iterations, basing on the solutions of equivalent linear methods [55]. This group also includes ICSM [54], [33] and ACSM [11], [10] which are actually improved versions of the existing CSM and which implement statistically optimized linearized parameters and adaptive algorithms for determination of target displacement level. By implementing DCM only TDA is conducted, employing the principle of multiplication of a group of coefficients which takes into account influence of various factors of structural behaviour.…”

Predicting displacement demand of multi-storey asymmetric buildings by nonlinear static analysis and corrective eccentricities

“…This applies also to nonlinear static methods adopted in other seismic codes. Based on this consideration, methods specifically improved for 3D structures have been proposed [16][17][18][19][20][21]. For instance, Kreslin and Fajfar developed an improved version of the N2 method called extended N2 method [18].…”

“…For instance, multi-storey buildings with r.c. framed structure are analysed in references [18][19][20] to investigate the effectiveness of the corrective eccentricity method and the extended N2 method. However, the adopted numerical model neglects the effect of the biaxial bending as well as the interaction between bending moment and axial force, which is important for this kind of structures [29,30].…”

Evaluation of the American Approach for Detecting Plan Irregularity

“…e response of asymmetric buildings was investigated by varying several parameters like centre of mass (CM), eccentricity [13], uneven distribution of concrete strength [14,15], torsional stiffness, and periods of vibration [16]. Furthermore, several studies were developed focusing on the application of nonlinear static analysis to in-plan irregular buildings [17][18][19][20][21][22]. en, an important contribution that deals with torsion issue and plan regularity of building structures is provided by Anagnostopoulos et al [23].…”