Fragility Analysis of Space Reinforced Concrete Frame Structures with Structural Irregularity in Plan

Abstract

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 threedimensional 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.

System‐Level Seismic Risk Assessment of Bridge Transportation Networks Employing Probabilistic Seismic Hazard Analysis

“…To account for uncertainty in the seismic damage states of bridges, seismic fragility curves are introduced. Seismic fragility is defined as the conditional probability that the demand of a structure exceeds a specified threshold for a given earthquake intensity [40][41][42], and seismic fragility curves are often used for setting retrofit and repair priorities of bridges after an unexpected and disastrous event [43]. In this study, SA, which can be calculated by the GMPE provided in equation 4, is introduced as the earthquake intensity.…”

Seismic Fragility Analysis of Steel Liquid Storage Tanks Using Earthquake Ground Motions Recorded in Korea

“…The analysis results of these studies showed that earthquake damages to structures varied with different ground motion properties. In addition, for an accurate seismic fragility analysis of structures, numerous studies on seismic fragility assessments using analytical models [3][4][5][6][7][8][9][10] have utilized real ground motion records from world-wide well-known earthquakes. However, these records may not reflect the characteristics of a specific region.…”

“…In addition, earthquakes have frequently occurred in the southeastern part of Korea in recent years, exposing these many industrial complexes to seismic hazards. Thus, the importance of structural risk assessment has become increasingly important, and there have been continuous efforts to mitigate earthquake damages using seismic fragility analyses [3,4]. This study concentrates on the structural fragility of liquid storage tanks.…”

“…The characteristics of earthquake ground motions are also a critical factor in the seismic fragility of structures. Previous studies [3][4][5][6] investigated the seismic fragility of structures with various types of earthquake ground motions to determine the effects of ground motion characteristics.…”

Collapse Risks of Fail-Safe RC Frames Due to Earthquakes: Fragility Assessments

“…Differences between two parts of the country were markedly observed. Moon, et al [12] employed a fragility approach to investigate the effect of plan structural irregularity and confirmed that the more irregular the structures, the higher the risk they pose. Meanwhile, the effect of the soilstructure interaction on the fragility curves was investigated by Anvarsamarin, et al [13] with the finding that adopting the average spectral acceleration (S a.avg ) intensity measure is more efficient in capturing the effect of the inherent uncertainties of strong ground motions on the structural response parameters.…”