Dynamic Safety Analysis of Multistory Buildings

The response of multistory buildings to a class of nonstationary random excitation of earthquake type is obtained under the assumption that the building can be treated as a shear beam with damping properties that make the model analysis possible. Two different distributions of the shear rigidity along the height of the building are considered. The story rigidities ki are constant for Structure I, while, for Structure H, larger for lower stories is usually the case in reality. The variance of the story displacement is computed as the significant response. Moreover, the probability that a specified level of stresses in the columns of the building will be exceeded, is estimated at each story for a measure of safety. As expected, Structure II has a better design since each story has a similar probability of attaining the same level of stress. This suggests that the analysis of this type may be useful for comparison of the safeties of different structures subjected to the same loading.