The results obtained using the ASCE7-10 provisions are highly unconservative for long-period buildings and for structures designed using higher response modification factors. It was found that the requirements of the ASCE7-10 provisions lead to underestimations of drift demands when live loads are nearly permanent.

Results from a parametric study are presented in terms of the drift response of multi-story shear buildings supporting blocks with the possibility to slide, compared to the drift response of the same multi-story buildings but supporting 0% or 25% of the weight of the blocks as rigidly attached as required by ASCE7-10 for commercial and storage structures, respectively. After successfully comparing with the results of finite element analyses and shake table tests, the model was used to evaluate the adequacy of the standard in relation to the treatment of live load as inertia. This paper presents the development of a lumped-parameter model of a multi-story shear building supporting rigid blocks that can slide. However, for storage and some commercial facilities live loads may continuously be present and even exceed the dead load. This contribution of live load as inertia seems to correlate with the low likelihood that live load objects be present at the time of occurrence of the design earthquake. For the purpose of estimating seismic loads Standard ASCE7-10 requires calculating the effective seismic weight which includes dead load, partitions and permanent equipment, plus 25% of the floor live load in areas used for storage.

Seismic analysis and design of buildings rely on the proper estimation of the mass that effectively contributes as inertia forces on the structure.

Asce 7 2010 free pdf