Techno Press
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Earthquakes and Structures   Volume 10, Number 1, January 2016, pages 211-238
Combination rules and critical seismic response of steel buildings modeled as complex MDOF systems
Alfredo Reyes-Salazar, Federico Valenzuela-Beltran, David de Leon-Escobedo, Eden Bojorquez-Mora and Arturo Lopez Barraza

Abstract     [Full Text]
    The Maximum seismic responses of steel buildings with perimeter moment resisting frames (MRF), modeled as complex MDOF systems, are estimated for several incidence angles of the horizontal components and the critical one is identified. The accuracy of the existing rules to combine the effects of the individual components is also studied. Two and three components are considered. The critical response does not occur for principal components and the corresponding incidence angle varies from one earthquake to another. The critical response can be estimated as 1.40 and 1.10 times that of the principal components, for axial load and interstory shears, respectively. The rules underestimate the axial load but reasonably overestimate the shears. The rules are not always inaccurate in the estimation of the combined response for correlated components. On the other hand, totally uncorrelated (principal) components are not always related to an accurate estimation. The correlation of the individual effects (ρ) may be significant, even for principal components. The rules are not always associated to an inaccurate estimation for large values of ρ, and small values of ρ are not always related to an accurate estimation. Only for perfectly uncorrelated harmonic excitations and elastic analysis of SDOF systems, the individual effects of the components are uncorrelated and the rules accurately estimate the combined response. The degree of correlation of the components, the type of structural system, the response parameter under consideration, the location of the structural member and the level of structural deformation must be considered while estimating the level of underestimation or overestimation.
Key Words
    critical response; steel buildings; seismic design codes; combination rules; effect of individual components; correlation of effects; MDOF and SDOF systems
Alfredo Reyes-Salazar, Federico Valenzuela-Beltran, Eden Bojorquez-Mora and Arturo López Barraza: Facultad de Ingeniería, Universidad Autónoma de Sinaloa, Ciudad Universitaria, Culiacán Sinaloa, Mexico

David de Leon-Escobedo: Facultad de Ingenieria, Universidad Autónoma del Estado de Mexico, Ciudad Universitaria, Toluca, Estado de Mexico, Mexico

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