Benchmarking Seismic Performance of Reinforced Concrete Frame Buildings

With the ultimate goal to benchmark the seismic performance of new (building-code compliant) reinforced concrete frame structures, we have applied a probabilistic assessment methodology, developed by the Pacific Earthquake Engineering Research Center, to a four-story office building. A key component of the assessment is characterization of the structural response through nonlinear time history analyses organized using an Incremental Dynamic Analysis approach. The results show that the seismic performance of the building is generally consistent with the expectations of current building codes, having a life-safety performance level (ASCE 356) for the 2% in 50 year event. A sensitivity study shows that the record-to-record variability is the single most important contributor to the total variability in structural response; however, the cumulative affect of other modeling and design uncertainties is also shown to be significant – resulting in the total dispersion being roughly double the dispersion due to record-to-record effects. To further investigate modeling uncertainties, we have compared the responses predicted by using a force-based fiber model and a lumped plasticity model. These comparisons show that the concrete tensile strength and tension stiffening effect significantly impact the response predictions, especially for structures with highly under-reinforced members subjected to lower ground motion intensity levels.