Extension of the CSM-FEMA440 to plan-asymmetric real building structures

Abstract

SUMMARYThe capacity spectrum method (CSM) has established itself as one of the most used Nonlinear Static Procedures for the seismic assessment of structures, since its introduction in 1975, when it was first presented by Freeman. More recently, this procedure was implemented in the ATC40 guidelines and lately improved in the FEMA-440 report. The first step of work addressed by this paper relates to the comparison between the two features of the CSM. In the second part, an extension of the FEMA-440CSM version is proposed for plan-asymmetric real RC building structures. The case studies under analysis are the SPEAR building-an irregular 3D structure representing typical old three-storey buildings in the Mediterranean region, from the early 1970s-and two real Turkish buildings with five and eight storeys. The CSM-ATC40, the CSM-FEMA440 and the proposed extended CSM-FEMA440 method are applied and the results obtained duly compared with nonlinear dynamic timehistory analyses. For the latter, semi-artificial ground motions are used to define the seismic action.

Performance assessment of irregular RC buildings with shear walls after Earthquake

“…As mentioned before, preceding studies showed that plan-wise irregular buildings require 3-D modeling due to the torsional behavior under seismic excitation [13][14][15][16][17][18][19][20][21][22][23][24][25]. Structural schemes of Figure 3 provide evidence that one of the RC structures is irregular in plan.…”

“…In the case where irregularities are dominant, those procedures are flawed, since they do not have a robust background. To overcome those deficiencies scientists developed 3D pushover techniques to take into account the torsional effects [13][14][15][16][17][18][19][20][21][22][23][24][25]. In their study Fajfar et al [16] stated that with an increase of plastic deformations the torsional effects tend to decrease.…”

Seismic fragility analysis of concrete encased frame‐reinforced concrete core tube hybrid structure based on quasi‐static cyclic test

“…The limit states of IO, CP, and GI are defined by FEMA 350. [39,40] As the IDA curve exhibits distinct elastic linear region, it signifies the IO structural performance level; in this stage, no damage in stiffness and bearing capacity occurs. With the increase of IM, softening segment is observed.…”

“…In this paper, limit states of immediate occupancy (IO), collapse prevention (CP), and global instability (GI) are adopted for evaluating seismic performance of hybrid structure. The limit states of IO, CP, and GI are defined by FEMA 350 . As the IDA curve exhibits distinct elastic linear region, it signifies the IO structural performance level; in this stage, no damage in stiffness and bearing capacity occurs.…”

Proposal of A Non Linear Static Analysis Procedure for Bridges: The Incremental Modal Pushover Analysis for Bridges (IMPAβ)

“…Indeed, more recently, many studies aimed to define innovative methodologies [25][26][27][28][29] alternative to what is nowadays considered the most reliable approach: the Incremental Dynamic Analysis (IDA). In fact, IDA requires to perform a set of nonlinear response history analysis, on a detailed three-dimensional numerical model of the structure, for a set of ground motions, each scaled for various intensity levels, selected to cover a wide range of structural responses [8,9,30].…”