Abstract

VALENZUELA BELTRAN, Federico et al. Combination rules of the effects of three components of earthquakes and critical response. Ing. sísm [online]. 2015, n.92, pp.65-94. ISSN 0185-092X.

The accuracy of the 30% and SRSS rules, the critical orientation of the components of earthquakes, and some related issues, are studied in this work. Complex structural models representing low and medium height buildings are analyzed. A statistical analysis of the precision of the combination rules, applied to individual and multiple response parameters, is performed. The effect of the correlation of the components of earthquakes in such precision is also studied. Finally, several analyses with various incidence angles of the components are performed with the purpose of finding the critical orientation. Results show that the rules underestimate the axial load in columns, but reasonably overestimate the interstory shears. Both rules are more conservative when the models are excited by the three components. The individual effects may be highly correlated, even for principal components. The rules are not always accurate for small values of correlation coefficients, and high values of such coefficients are not always related to an inaccurate estimation of the combined response. The accuracy of the combination rules depends on the degree of correlation of the components, the response parameter, the location of the considered member and the level of structural deformation.

Keywords : seismic design codes; steel buildings; combination rules; correlation of individual effects; critical response.

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