Displacement based and consolidated force/displacement based methods for seismic assessment of steel moment resisting frames

The major guidance documents for seismic assessment of existing buildings are ASCE 41-06 in US, Eurocode 8 Part 3 in Europe, and NZSEE recommendations in New Zealand. All of these guidelines have proposed using nonlinear static analysis as a tool for seismic assessment of buildings. In New Zealand recommendations there is a parameter %NBS which means percentage of new building standard, the building with %NBS = 100 is a building that satisfies standards of a new building. NZSEE recommendations have proposed force based, displacement based and consolidated force/displacement based methods for seismic assessment of existing buildings. Consolidated force/displacement based method is a combination of force based and displacement based methods. Displacement based method has a direct emphasis on estimating the ultimate displacement capacity of the structure. In this paper, 5- and 10-story steel moment resisting frames have been designed with %NBS approximately equal to 100, calculated by displacement based and consolidated force/displacement based methods. In these methods, the nonlinear static analysis is used for estimating strength and deformation capacity of steel moment resisting frames. Nonlinear dynamic analysis procedure is applied to assess the seismic performance of these structures according to ASCE 41-06.