Abstract
The nonlinear seismic responses of 3D steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (IGF) are studied explicitly considering the contribution of the IGF. The effect on the structural response of the stiffness of the beam-to-column connections of the IGF, which is usually neglected, is also studied. It is commonly believed that the flexibility of shear connections is negligible and that 2D models can be used to properly represent 3D real structures. The results of the study indicate, however, that the moments developed on columns of IGF can be considerable and that modeling buildings as plane frames may result in very conservative designs. The contribution of IGF to the lateral structural resistance may be significant. The contribution increases when their connections are assumed to be partially restrained (PR). The incremented participation of IGF when the stiffness of their connections is considered helps to counteract the no conservative effect that results in practice when lateral seismic loads are not considered in IGF while designing steel buildings with PMRF. Thus, if the structural system under consideration is used, the three-dimensional model should be used in seismic analysis and the IGF and the stiffness of their connections should be considered as part of the lateral resistance system.
Highlights
Introduction and ObjectivesDifferent structural configurations, structural systems, and materials are generally used to improve structural behavior during seismic excitations
The incremented participation of interior gravity frames (IGF) when the stiffness of their connections is considered helps to counteract the no conservative effect that results in practice when lateral seismic loads are not considered in IGF while designing steel buildings with perimeter moment resisting frames (PMRF)
If the structural system under consideration is used, the three-dimensional model should be used in seismic analysis and the IGF and the stiffness of their connections should be considered as part of the lateral resistance system
Summary
Structural systems, and materials are generally used to improve structural behavior during seismic excitations. The contribution of these connections to the structural strength and stiffness can be very important if the composite action of the concrete slab is considered [15, 16] Even though it is not an objective of this paper to compare the seismic responses of steel buildings with PR and FR connections, it is important to mention that in some studies [17,18,19,20,21] it was shown that the maximum values of base shear and interstory displacements of plane steel frames under earthquake ground motions were reduced when PR connections were used. The procedure can consider material and geometric nonlinearities and that produced by partially restrained (PR) connections
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