The extended consecutive modal pushover procedure for estimating the seismic demands of two-way unsymmetric-plan tall buildings under influence of two horizontal components of ground motions

Summary Pushover methods for seismic assessment of buildings under multidimensional earthquakes have been studied and retrofitted. However, these current methods are not suitable when applied to widely adopted arch‐type structures characterized by strong geometrical nonlinearity and coupling effects. An improved multidimensional modal pushover procedure with two‐stage analyses is proposed for seismic evaluation of latticed arches. Taking overall multidimensional response into consideration, modal stiffness of the equivalent single‐degree‐of‐freedom system is derived, and its capacity curve is determined during the first‐stage analysis. To provide a deformation profile with algebraic signs of response retained, the second‐stage analysis is conducted using the pushover load pattern derived from modal displacement superposition. The objective of the improved procedure is to overcome the drawback of the conventional modal pushover method, which describes the capacity curve resorting to base shear and roof displacement, and that of quadratic combination rules which eliminate the sign reversals of response. To validate its serviceability, nodal displacements and element stresses, as well as the yielding members, of two typical latticed arches are calculated. Through comparative analysis, the results by the improved procedure exhibit good agreement with those by response history analysis. Additionally, this procedure demonstrates great superiority over the conventional method for its satisfying accuracy.

Section: Introductionmentioning

confidence: 99%

An improved multidimensional modal pushover analysis procedure for seismic evaluation of latticed arch‐type structures under lateral and vertical earthquakes

Luo

Zhu

et al. 2019

“…This method is based on both single‐stage and multistage pushover analyses; the structural seismic demand is the envelope value of the single‐stage and multistage analysis results. Furthermore, Poursha et al extended this method to bidirectional asymmetric structures under two horizontal seismic forces. Subsequently, this consecutive modal pushover procedure was modified to improve the accuracy of estimating the seismic responses of high‐rise buildings .…”

Section: Introductionmentioning

confidence: 99%

Combination model for conventional pushover analysis considering higher mode vibration effects

Guan

Liu

et al. 2019

Summary This paper aims to propose a combination model for conventional pushover analysis with invariant lateral load patterns to consider the effects of higher mode vibrations on the seismic responses of high‐rise buildings. Rectangular concrete‐filled steel tubular (RCFT) structures having two types of deformation, namely, shear type RCFT frame structures and shear‐flexural type RCFT frame‐shear wall structures, are selected and investigated. Finite element models are created using Perform‐3D. Both pushover analysis with three conventional lateral loading patterns, namely, uniformly distributed loading, first‐mode vibration loading, and concentrated loading at the vertex, and time‐history analysis with 15–21 earthquake records chosen for each RCFT structure are performed. Regression analysis is used to fit the interstory drift ratios obtained by the pushover analysis with those from the time‐history analysis. Further, the relations between the partial regression coefficients and the structural fundamental periods under certain lateral loading patterns are analyzed. On this basis, using these conventional lateral loading patterns, combination models for high‐rise buildings with two types of deformation are proposed and verified. The results demonstrate that the proposed method can estimate the seismic responses of high‐rise buildings with a high accuracy and has the advantages of ease of implementation and operation.

“…In the MMP, the effect of higher modes is lumped into a single invariant lateral load distribution that is proportional to the seismic masses at the floor levels. In another study, Poursha et al proposed the consecutive modal pushover (CMP) procedure in which single‐stage and multistage pushover analyses are utilized. The final seismic responses are determined by enveloping the results obtained from the single‐stage and multistage pushover analyses.…”

Section: Introductionmentioning

confidence: 99%

Prediction of the force demands of tall buildings through the enhanced pushover procedures

Amini

Poursha

2018

Self Cite

Summary This paper attempts to comprehensively evaluate the accuracy of the enhanced pushover procedures in estimating the force demands of tall building structures. In this process, the efficiency of different pushover methods in taking the higher modes effect into account for the computation of the force demands is assessed. The enhanced pushover methods including the modal pushover analysis, force‐based adaptive pushover, displacement‐based adaptive pushover, consecutive modal pushover (CMP), single‐run multimode pushover (SMP), nonadaptive displacement‐based pushover, and adaptive force‐based multimode pushover procedures, as well as the conventional pushover analysis, are applied to the three special steel moment‐resisting frames to compute the internal force demands of structural members. The seismic force demands resulting from the enhanced pushover procedures are compared with those from the nonlinear response history analysis (NL‐RHA) as a benchmark solution. Furthermore, in order to evaluate approximately the degree to which the higher modes may affect deformation and force demands of tall buildings, the ratio of structural demands computed by the NL‐RHA to those obtained by the conventional pushover analysis is determined. The results demonstrate that the CMP and SMP procedures can accurately estimate the force demands of tall buildings. It is shown that the effects of higher modes on the story drifts and column shear forces and bending moments are larger than those on the other force demands.