A Probabilistic Seismic Demand Model for Regular Highway Bridges

Probabilistic seismic demand models are important for the design of structures based on the seismic probability and the performance of the structure. In this paper, the probabilistic seismic demands of 8 representative regular highway bridges are calculated using the cloud approach by selecting 2390 earthquake records for 3 different site conditions. These demands are expressed in terms of an intensity measure (IM), which is the spectral acceleration at the fundamental period with 5% damping, and an engineering demand parameter (EDP), which is the drift ratio at the top of pier. The probability distributions of the EDP are established at several IM levels. The results show that the EDPs have reasonably standard beta distributions at different IM levels. A correlation between the mean EDP and the IM is also established using regression analysis. The probabilistic seismic demand model is suitable for 3 different site conditions and can greatly simplify the calculation of seismic demand in the probability-based and performance-based seismic design of regular bridges.