Correlation Between Structure-Specific Seismic Intensity Measures of Site-Dependent Ground Motions and Nonlinear Response of R/C Frame-Structures

Abstract eng:
The assessment of the seismic performance of a structure depends on the optimal choice of an earthquake Intensity Measure (IM). Given the fact that conventional IMs based only on ground motion information might not be able to successfully predict the seismic response of structures, several advanced structural-specific IMs have been proposed during the past years, taking into account not only earthquake characteristics but also structural information. Moreover, local site conditions may generate large amplifications as well as spatial variations in the ground motions, which influence the intensity measures and in most cases lead to important structural damage. Along these lines the objective of this paper is to study the correlation between well-known structure-specific intensity measures and the inelastic response of multi-story reinforced concrete planar frames taking into account site effects. First, site dependent ground motions are produced considering 2D analysis of the soil profile via Boundary Element Method (BEM) numerical technique. Three different geological configurations are considered that account for (i) uniform excitation, ii) canyon topography and iii) complex hills topography. Next, we focus on the dynamic behavior of two reinforced concrete frames (a symmetric and an asymmetric one) modeled and analyzed by the Finite Element Method (FEM). The buildings are subjected to a set of site-dependent strong motions and the expected structural damage state of each building is determined in terms of the Maximum Interstory Drift Ratio (MIDR). Then, a number of structure-specific seismic intensity measures is computed from the aforementioned site-dependent ground motions. The examined intensity measures take into account special characteristics of both the earthquake record and the building under consideration. The values of the MIDRs are correlated with the structure-specific ground motion intensity measures. In sum, the numerical results of this study show that certain intensity measures exhibit strong correlation with the seismic damage of the two buildings. However, their adequacy for estimation of structural response depends strongly on the local site conditions under investigation.

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