Quantitative Assessment Framework for the Postearthquake Traffic Flow Capacity of Bridges Based on the Loss Model of Vertical Load-Carrying Capacity

This paper aimed to propose an analytical framework for assessing the postearthquake traffic flow capacity of girder bridges based on the loss model of vertical load-carrying capacity. For this purpose, a loss model of the vertical load-carrying capacity of a reinforced concrete (RC) column associated with the residual drift ratio and the damage level (i.e., the modified Park-Ang index) was developed to determine the postearthquake vertical load-carrying capacity accurately and quantitatively. Subsequently, the probability seismic demand analysis (PSDA) was performed to obtain the probability distribution functions (PDFs) of engineering demand parameters (EDPs) (i.e., the residual drift and the damage indicator) and the PDF of postearthquake vertical load-carrying capacity was determined based on the developed loss model. Furthermore, the reliability analysis was utilized to calculate the postearthquake reliability index of a bridge by adjusting the mean values of the live load (which reflects the traffic flow capacity), and the postearthquake traffic flow capacity could then be quantitatively determined based on the live load ratio at a target reliability index. Finally, the proposed framework was implemented on a single-column bridge to demonstrate its efficiency. Compared to traditional qualitative and subjective postearthquake functionality assessment of the damaged bridge, the proposed analytical approach offered a mathematical model for the decision-making process.