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Unbonded posttensioned controlled rocking masonry walls (PT-CRMWs) have been increasingly studied in the last decades due to their promising results regarding seismic resilience. However, implementing posttensioning (PT) has still some drawbacks, such as construction challenges, PT losses, and yielding during a seismic event. In response, this study investigates a newly proposed energy dissipation-controlled rocking masonry wall (ED-CRMW), which eliminates the use of unbonded posttensioned bars and relies instead on gravity loads to self-center the wall to its vertical plumb while incorporating an energy dissipation (ED) device to limit seismic displacements. The study presents a design approach for the proposed system, including the influence of higher mode effects. In this respect, a multispring macro model is developed using OpenSees and validated against recent experimental results by the authors. Next, as no distinct values are yet provided in ASCE 7, the seismic response modification factor is investigated using collapse risk analysis. Specifically, using the validated model, nonlinear static and dynamic analyses are performed to 20 ED-CRMW archetypes with different design configurations. The results demonstrate that the design objectives were achieved and that a seismic response modification factor of 7 assigned to the selected design configurations meets the FEMA P695 acceptance criteria for seismic collapse risk under the maximum considered earthquake (MCE). [ABSTRACT FROM AUTHOR]

Because significant damages to structures having structural irregularity in their plans were repeatedly observed during many past earthquakes, there have been great research efforts to evaluate their seismic vulnerability. Although most of the previous studies used simplified structural representations such as one-dimensional or two-dimensional models in the fragility analysis of plan-irregular structures, simple analytical models could not represent true seismic behavior from the complicated nonlinear coupling between lateral and torsional responses as the degree of irregularity increased. For space structures with high irregularity, more realistic representations such as three-dimensional models are needed for proper seismic assessment. However, the use of computationally expensive models is not practically feasible with existing approaches of fragility analysis. Thus, in this study, a different approach is adopted that can produce vulnerability curves efficiently, even with a three-dimensional model. In this approach, an integrated computational framework is established that combines reliability analysis and structural analysis. This enables evaluation of the limit-state faction without constructing its explicit formula, and the failure probability is calculated with the first-order reliability method (FORM) to deal with the computational challenge. Under the integrated framework, this study investigates the seismic vulnerability of space reinforced concrete frame structures with varying plan irregularity. Material uncertainty is considered, and more representative seismic fragility curves are derived with their three-dimensional analytical models. The effectiveness of the adopted approach is discussed, and the significant effect of structural irregularity on seismic vulnerability is highlighted. [ABSTRACT FROM AUTHOR]

To consider the effect of higher modes in predicting the seismic responses of midrise buildings, as well as the progressive changes in the dynamic characteristics during the nonlinear analysis, an adaptive force-based multimode pushover (AFMP) procedure is presented. This procedure is an adaptive version of the single-run multimode pushover (SMP) procedure that it is envisaged to be an enhancement of the previously proposed procedure. The procedure encompasses some adaptive pushover analyses. First, an adaptive single-mode pushover analysis using the first mode shape is performed. Moreover, one or two adaptive multimode pushover analyses are implemented by means of the enhanced lateral load distributions calculated by algebraically adding the instantaneous modal story forces. Therefore, the sign reversals of load vectors in the higher modes are considered. The results obtained through the adaptive single-mode and multimode pushover analyses are enveloped to compute the final seismic responses. It is demonstrated that the AFMP procedure can estimate with acceptable accuracy the seismic responses of midrise building frames. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of the seismic response of a 0.6-scale three-story building with nonlinear viscous dampers under the design basis earthquake (DBE) and the maximum considered earthquake (MCE). The test structure consists of a moment-resisting frame (MRF) with reduced beam sections (RBS), a frame with nonlinear viscous dampers and associated bracing (called the DBF), and a gravity load system. The paper focuses on quantifying and assessing the seismic response of the test structure under the DBE and MCE. Three MRF designs were studied for 100, 75, and 60%, respectively, of the required base shear design strength according to ASCE 7-10. The DBF with nonlinear viscous dampers was designed to control the lateral drift demands. Earthquake simulations using ensembles of ground motions were conducted using the real-time hybrid simulation method. Experimental results show that a high level of seismic performance can be achieved under DBE and MCE ground motions, even for a building structure designed for as little as 60% of the design base shear strength required by ASCE 7-10 for a building structure without dampers. [ABSTRACT FROM AUTHOR]

This study presents an evaluation of drift demands and their associated uncertainties for nondeteriorating regular moment resisting frame structures subjected to ordinary ground motions (i.e., without near-fault effects). The only source of uncertainty considered is the uncertainty due to differences in the frequency content of the ground motions. The information presented in this study is deemed to be useful for preliminary design and seismic performance assessment in which the performance targets of interest are those related to damage and loss of function (downtime). Thus, the focus is on ductility levels that are not so large that they cause significant cyclic deterioration in the components of the structural system. The dependence of drift demands (the maximum roof drift, the average of maximum story drifts, and the maximum story drift over the height) on relative ground motion intensity, fundamental period, and number of stories is investigated. [ABSTRACT FROM AUTHOR]