Verification of performance criteria using shake table testing for the vulnerability assessment of reinforced concrete buildings

Abstract

Shake table experiments are conducted to support the selection of performance criteria and to verify the inelastic modeling approach for developing the fragility functions of reinforced concrete buildings. Two frames representing the lateral force-resisting system of a preseismic code building are tested under the effect of an earthquake record with increasing severity. Shear failure is detected in columns at a PGA of 1.28g before other failure modes, which was effectively predicted by the fiber-based numerical model, performance criteria, and shear supply approaches adopted for vulnerability assessment. Five buildings, ranging from 2 to 40 stories, are then assessed under the effect of far-field and near-source earthquake records, considering the experimentally verified modeling approach and shear failure prediction models that account for flexural ductility and shear-axial force interaction. The impact of considering shear response on the vulnerability assessment results is considerable, particularly for the lower-height wall structures when subjected to the near-source earthquake scenario. Higher modes dominate the behavior of wall structures, principally under the latter seismic scenario, and shift their response to shear-controlled. Therefore, seismic scenario-structure-based performance criteria are adopted for developing a range of analytically derived, experimentally verified fragility functions for the earthquake loss estimation of buildings with different characteristics.

Seismic Fragility Assessment of an Existing Multi-Span RC Bridge Equipped with Risk Mitigation Systems

“…In addition to the verifications previously made in other studies for the modeling approaches of the RC structures through shake table experiments [37,38], the idealization adopted in the current probabilistic assessment study for existing and retrofitted bridge bents was verified before implementing it at the bridge level. The verification process ensured that the utilized modeling approach realistically predicted the seismic performance of the existing and retrofitted bridge.…”

“…This analysis platform can predict the structural behavior under static or dynamic loadings, considering geometric nonlinearities, and material inelasticity [40]. Several recent studies have verified the fiber-based modeling approach adopted by this analysis platform [37,38]. Each structural member was modeled using several inelastic displacement-based frame elements to increase the analysis accuracy.…”

“…This study considered fourteen input ground motions representing seven far-field and seven near-source earthquake records. These earthquakes were deemed suitable for the study area and were used in previous vulnerability assessment studies of structures [35][36][37]49]. The means of the selected input ground motions match the means of 40 earthquake records used in the previous seismic assessment studies for the study area.…”

“…Shear demands exceeded the shear supply calculated based on the conservative design provisions. The shear supply was calculated based on the bridge column cross-section and reinforcement using the shear strength model of the design code and compared with the shear demand during time history analysis, as discussed by Mwafy and Almorad [37]. The seismic demands and damage observed in the bridge under the effects of earthquake records representing far-field and near-source input ground motions when scaled to the design earthquake confirmed the major differences between the seismic responses of the bridge in the two orthogonal directions.…”

“…Accordingly, bridges constructed in the UAE in the 1990s and before may be vulnerable to losses due to the possible lack of adequate seismic provisions at their construction times [34]. In addition, several probabilistic assessment studies were conducted in the UAE for different types of regular and irregular buildings with different structural systems, building heights, and construction dates [35][36][37]. The previous vulnerability assessment and seismic hazard studies in the UAE concluded that substandard and pre-code structures might be vulnerable to damage under the following seismic scenarios: (i) near-field events originating from local sources and (ii) far-field earthquakes generated from regional faults.…”