Seismic loss assessment of seismically isolated buildings designed by the procedures of ASCE/SEI 7-16

Abstract

This paper investigates the seismic loss assessment of seismically isolated and non-isolated buildings with steel moment or braced frames, designed by the seismic design standard of ASCE/SEI 7-16. The seismic loss is calculated from the damage to structural and non-structural components, as well as the demolition and the collapse of buildings. This study demonstrates that the expected annual losses for seismically isolated buildings are half or less than half of those calculated for non-isolated buildings. These losses depend on the types of seismic isolation systems and seismic force resisting systems used. Among the cases of isolated buildings studied in this paper, the most cost-effective systems are found to be the buildings designed by minimum strength requirement in ASCE/SEI 7-16 and with isolators which have displacement capacity 1.5 times larger than the minimum required in ASCE/SEI 7-16, in terms of expected annual losses. This study also compares the results obtained from different approaches of selection and scaling of ground motions. The following research finds that when Incremental Dynamic Analysis approach with far-field ground motion set in FEMA P695 is used, the computed expected total annual losses become doubled from the Conditional Spectra approach.

Performance evaluation of seismically isolated buildings near active faults

“…Previous studies by the authors 13,14 and others 15,16 investigated the collapse performance of seismically isolated buildings designed by the ASCE/SEI 7 standards 9,17 when located at far-field sites using the FEMA P695 procedures. Another study 19 focused on the collapse performance of sliding isolation bearings in buildings when subjected to recorded pulselike motions but did not address the performance of the buildings designed based on the ASCE standard.…”

“…This approach incorporates the effects of pulse-like ground motions by considering the probability distributions of pulse-period and occurrence of pulse-like ground motions, which were not considered in previous studies 20,30 . This paper utilizes the same archetypical six-story buildings with perimetric steel special concentrically braced frames (SCBF) that has been previously used 13,14,28,29,31,32 but re-designed to be located at near-field sites. Moreover, the buildings designed for this study have superstructure strengths and isolation system capacities larger than the minimum requirements of ASCE/SEI 7-16.…”

“…Moreover, the buildings designed for this study have superstructure strengths and isolation system capacities larger than the minimum requirements of ASCE/SEI 7-16. The seismic performance of seismically isolated buildings designed to just satisfy the minimum requirements of ASCE/SEI 7-16 9 was previously studied by authors 13,14,28,29 for far-field ground motions. Those studies showed that minimally designed seismically isolated buildings in the far-field might have unacceptable probabilities of collapse.…”

“…2. Isolation system 2: The isolators are triple friction pendulum bearings with the geometric and frictional properties of isolator TFP-3 13,14,28,29 and with linear fluid viscous dampers added in the isolation system. The ultimate displacement capacity of this isolation system as finally configured is 973 mm.…”

“…3. Isolation system 3: The isolators are triple friction pendulum bearings with the geometric and frictional properties of isolator TFP-3 13,14,28,29 but with increased displacement capacity (all geometric properties are the same but the main concave plates are larger). The ultimate displacement capacity of this isolation system as finally configured is 1461 mm.…”