GLOBAL AND LOCAL PERFORMANCE LEVELS ON THE PROBABILISTIC EVALUATION OF THE STRUCTURAL POUNDING EFFECT BETWEEN ADJACENT RC STRUCTURES

摘要

In this study the seismic performance of a real multistory RC frame structure against pounding with an adjacent shorter and stiffer structure is evaluated based on probabilistic assessment methods. The examined pounding case is between an 8-story RC frame and a 3-story rigid barrier (very stiff structure) with equal story heights (floor-to-floor interaction). Three different initial gap distances (dg) between the adjacent structures are considered. The seismic performance of the 8-story structure without the pounding effect is also included for comparison reasons. The probabilistic evaluation of the pounding effect is performed through fragility curves in terms of global and local engineering demand parameters (EDPs) as a function of the intensity measure (IM). For this purpose, linear and bilinear regression models in log-log space have been considered to define the relationship between the examined EDPs and IMs. The commonly used intensity measures (IMs) of peak ground acceleration, PGA and that of spectral acceleration corresponding to the fundamental period of the examined structure, Sa(T 1,8-story) are adopted. Displacement and rotation EDPs that could control the global state of the structure are examined at different performance levels. However, the most critical issue in earthquake-induced interaction between adjacent structures is the local responses of the columns at the pounding side. Thus, three local performance levels in terms of ductility capacity of the external columns at each story level of the 8-story frame have also been incorporated in the probabilistic assessment of the pounding problem. The results of this study indicate that the probability of pounding between the examined structures is increased as the separation gap distance dg decreases. The fragility curves of the 8-story frame are significantly influenced due to the structural pounding effect. The probability of damage at columns seems to be an important parameter that has to be further investigated. Different types of global and local performance levels altered the intensity values for the seismic hazard of the structural pounding.