Abstract
The accuracy of seismic demand models in seismic vulnerability analysis of structures or components mainly depends on the seismic intensity measures (IMs) and engineering demand parameters (EDPs). This paper proposes a novel method to obtain the optimal seismic demand model for the seismic vulnerability analysis of bridges. The method obtains the IM-EDP combination by matching all IMs and EDPs within a wide range one by one, considering the contribution of multiple IM parameters to the seismic response of the structure and avoiding the blindness of EDP selection. The IM is determined by calculating Pearson correlation coefficient and partial correlation coefficient, controlling the correlation between EDP and IM (or IMs) to a minimum to reduce the multicollinearity within the vector IMs and avoid ill-conditioned models. The optimal seismic demand model is obtained by inspecting the scatter plot and residual plot of suboptimal seismic demand models determined from all combinations by guaranteeing efficiency and sufficiency. The efficiency of seismic demand models is guaranteed by controlling the root mean square error (RMSE) and the coefficient of determination (R2). The sufficiency of models is guaranteed by controlling the slope of fitted line. A continuous rigid frame bridge with double thin-walled piers is used as a case study and a dynamic time-history analysis is performed to obtain the seismic vulnerability of bridge with the proposed method. The results show that the proposed method is feasible and ideally suited for optimizing seismic demand model.
Highlights
As an important part of performance-based earthquake engineering, the purpose of seismic vulnerability analysis is to predict the damage degree of structures under varying levels of earthquake intensity, whereas the results of seismic vulnerability analysis are heavily influenced by the seismic demand model of the structure [1]
Seismic demand models (SDMs) describe the functional relationship between seismic intensity measures (IMs), which are a measure of the earthquake’s intensity, and structural engineering demand parameters (EDPs), which are a measure of the magnitude of the structural response under earthquakes
The structural damage caused by small earthquakes is possibly more serious than that caused by large earthquakes [2, 3]. is is because earthquake damage depends on the amount of energy released in the earthquakes, and on other factors such as the hypocentral distance, the soil type of the site, and structural characteristics [4]. erefore, the applicability of SDMs in seismic vulnerability analysis should be determined rigorously through optimization within a sufficiently wide range of IMs and EDPs
Summary
As an important part of performance-based earthquake engineering, the purpose of seismic vulnerability analysis is to predict the damage degree of structures under varying levels of earthquake intensity, whereas the results of seismic vulnerability analysis are heavily influenced by the seismic demand model of the structure [1]. Buyco and Jayaram et al [26, 27] found that the selection of EDP had a significant influence on the seismic vulnerability analysis results They found that the selected EDPs affect the efficiency and sufficiency of IMs. Considering the complexity of the site type and structural damage mechanism, it is necessary to carry out accurate and rigorous analysis to determine the relative optimal parameters for seismic demand models. Taking a continuous frame bridge with double thin-wall piers as an example, the optimal seismic demand model of the bridge is obtained by using the method and seismic vulnerability analysis is performed
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