Seismic Demands Of Buildings Research Articles

Correlation between pulse-like ground motion intensity measures and seismic demands of buildings with three structural systems (moment-resisting frames, structural walls and combination of moment-resisting frames and shear walls)

In this study, the distribution of correlation coefficients between maximum interstory drift ratio (MIDR) of multistorey building structures and ground motion characteristics intensity measures (IMs) is evaluated and compared. For this purpose, a continuum building model is used to estimate the MIDR of multistory building structure including higher mode effects. The MIDRs are computed for building structures with three different lateral resisting systems (structural walls, moment-resisting frames, and their combination) and fundamental periods that ranges from 0.05 to 10s. Nine different ground motion parameters of pulse-like ground motions including PGD, PGA, PGV, Ic, CAV, Ia, SMV, ESD, SMA are selected as ground motion characteristics IMs. The effects of the type of lateral resisting system and the acceleration pulse on the distribution of correlation coefficients are also considered in the study. Based on the assessment results, MIDRs in mid and long-period buildings show a high correlation to PGV, SED and SMV, while a low correlation occurs with respect to PGA and SMA. Also, type of lateral resisting system causes changes in the correlation coefficients and results showed that long-period shear wall structure gives lower coefficients with respect to other structural systems.

Approximate Quantification of Higher-Mode Effects on Seismic Demands of Buildings

Quantifying the higher-mode effects on the seismic demands of buildings may benefit not only the awareness of characteristics of the seismic responses of buildings, but also the development of rapid/simplified methods for the seismic assessment of buildings. This study proposes an approach that is applicable for quantifying the aforementioned effects, covering the full range of building heights and deformation types. The vehicle used in this proposed approach is the generalized building model, which has been modified from the conventional cantilever beam model. In addition to building height and deformation type, the strength ratio of each vibration mode and the site class of buildings are the parameters considered in this study. The higher-mode effects on floor displacements, inter-story drift ratios, floor accelerations, and base shears with relation to the aforementioned parameters are investigated. Finally, the proposed approach is verified via the investigation of the higher-mode effects of a 20-story exemplar building.

Estimating seismic demands of singly symmetric buildings by spectrum-based pushover analysis

Buildings with the singly symmetric plan are more vulnerable to earthquake actions than the buildings with a symmetric-plan arrangement since the torsional effect caused by the asymmetricity will induce higher seismic demand and may cause unexpected damage to the buildings. Thus, it is a crucial challenge for researchers and engineers to predict seismic demands of asymmetric-plan buildings for the possible strengthening and retrofitting. Although some pushover-based analysis methods have been proposed for the fast prediction of asymmetric-plan buildings, most of them do not reasonably consider the dynamic coupling of vibration modes. This paper expands the spectrum-based pushover analysis (SPA) procedure, which is proved to be effective in predicting seismic demands of buildings with symmetric building plans, to three-dimensional structure systems, to estimate the seismic demands of singly symmetric structures. A comprehensive case study, which includes six frame buildings with different structural heights and mass eccentricity ratios under various levels of the input motions, was conducted to investigate the feasibility of the SPA method in estimating the seismic demands of one-way asymmetric-plan buildings. It is found from the comparison of seismic demands computed from the SPA method, the nonlinear response time history analysis, the consecutive modal pushover analysis and the modal pushover analysis that the SPA method is capable of predicting the seismic demands very well, in particular, the demands on the heavy side of the structure, where the seismic demand and damage are more significant.

Extended consecutive modal pushover procedure for estimating seismic responses of one-way asymmetric plan tall buildings considering soil-structure interaction

Performance based design becomes an effective method for estimating seismic demands of buildings. In asymmetric plan tall building the effects of higher modes and torsion are crucial. The consecutive modal pushover (CMP) procedure is one of the procedures that consider these effects. Also in previous studies the influence of soil-structure interaction (SSI) in pushover analysis is ignored. In this paper the CMP procedure is modified for one-way asymmetric plan mid and high-rise buildings considering SSI. The extended CMP (ECMP) procedure is proposed in order to overcome some limitations of the CMP procedure. In this regard, 10, 15 and 20 story buildings with asymmetric plan are studied considering SSI assuming three different soil conditions. Using nonlinear response history analysis under a set of bidirectional ground motion; the exact responses of these buildings are calculated. Then the ECMP procedure is evaluated by comparing the results of this procedure with nonlinear time history results as an exact solution as well as the modal pushover analysis procedure and FEMA 356 load patterns. The results demonstrate the accuracy of the ECMP procedure.

Assessment of modal pushover analysis procedure for seismic evaluation of buckling–restrained braced frames

Buckling-restrained braced frame (BRBF) has become a viable choice of lateral-force resisting system for earthquake resistant buildings as its hysteretic behaviour is non-degrading and much hysteretic energy can be dissipated. Meanwhile, an improved pushover analysis procedure, called Modal Pushover Analysis (MPA), has been proposed by Chopra and Goel [(2002), Earthquake spectra, 20(1), 255–271] to include contributions of higher ‘modes’ in estimating seismic demands of buildings. The MPA procedure was demonstrated to provide reasonably accurate seismic demands compared with non-linear response history analysis (NL-RHA) when analysing moment-resisting frames. This research further examined the bias and accuracy of MPA procedure when it is applied to analyse 3-, 6-, 10- and 14-storey BRBF buildings due to two sets of strong ground motions having 2% and 10% probability of being exceeded in 50 years. The MPA estimates are compared with ‘exact’ results from NL-RHA. It was found that the peak roof displacement...