Incremental dynamic analysis applied to seismic risk assessment of bridges
Incremental Dynamic Analysis (IDA) is applied in a Performance-Based Earthquake Engineering context to investigate expected structural response and damage outcomes to highway bridges. This quantitative risk analysis procedure consists of: adopting a suitable suite of ground motions and performing IDA on a nonlinear model of the prototype structure; summarize and parameterize the IDA results into various percentile performance bounds; and integrate the results with respect to hazard intensity-recurrence relations into a probabilistic risk format. An illustrative example of the procedure is given for reinforced concrete highway bridge piers, designed to New Zealand, Japan and Caltrans specifications. It is shown that for bridges designed to a “Design Basis Earthquake” that has a 10 percent probability in 50 years with PGA = 0.4g, and detailed according to the specification of each country, should perform well without extensive damage. However, if a larger earthquake occurs, such as a maximum considered event which has a probability of 2 percent in 50 years, then extensive damage with the possibility of collapse may be expected.