Abstract
Brittle failure mechanisms can affect the seismic performance of structures composed of intersecting moment resisting frames, if the biaxial effects are not considered. In this research, the bidirectional cyclic response of H-columns with weak-axis moment connections was studied using numerical models. Several configurations of joints with bidirectional effects and variable axial loads were studied using the finite element method (FEM) in ANSYS v17.2 software. The results obtained showed a ductile behavior when cyclic loads are applied. No evidence of brittle failure mechanisms in the studied joint configurations was observed, in line with the design philosophy established in current seismic provisions. However, beams connected to the column minor axis reached a partially restrained behavior. Joints with four beams connected to the column exhibited a partially restrained behavior for all axial load levels. An equivalent force displacement method was used to compare the hysteretic response of 2D and 3D joints, obtaining higher deformations in 3D joints with respect to 2D joints with a similar number of connected beams. Consequently, design procedures are not capable of capturing the 3D deformation phenomenon.
Highlights
The steel moment frame is a structural system commonly used as an alternative in steel buildings.Horizontal members and vertical members are joined by means of fully or partially restrained moment connections
The cyclic response of weak-axis moment connections without pinching can be explained by the limited plastic strains reached in the beams up to 4% drift ratio, as a consequence of the low elastic stiffness provided by the weak axis of the column
A numerical study based on finite element models of M1, M2, M3 and M4 connections with different levels of axial load was performed
Summary
The steel moment frame is a structural system commonly used as an alternative in steel buildings. The lateral resistance is provided by flexural and shear mechanisms in beams and columns, capable of reaching high ductility levels In these systems, moment connections play an important role in their seismic performance and they may be designed according to [1], which includes seismic design requirements for connections commonly used in beam-to-column joints with wide flange columns and beams. The results obtained showed a ductile behavior of weak-axis Reduce beam section (RBS) connections, reaching 0.03 (rad) plastic rotation. Experimental research on wide flange beams, connected to wide flange columns, with large width–thickness ratios, subjected to a cyclic load about the weak-axis was performed [6]. A numerical study of the bidirectional cyclic response of weak-axis beam-to-column joints using end-plate moment connections was conducted. Several configurations of joints with bidirectional effects and variable axial loads were studied using the finite element method (FEM) in ANSYS software [12]
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