Techno Press

Steel and Composite Structures   Volume 22, Number 1, September20 2016, pages 141-159
Rotation capacity of composite beam connected to RHS column, experimental test results
Mohammadreza Eslami and Hisashi Namba

Abstract     [Full Text]
    Commonly in steel frames, steel beam and concrete slab are connected together by shear keys to work as a unit member which is called composite beam. When a composite beam is subjected to positive bending, flexural strength and stiffness of the beam can be increased due to "composite action". At the same time despite these advantages, composite action increases the strain at the beam bottom flange and it might affect beam plastic rotation capacity. This paper presents results of study on the rotation capacity of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. Due to out-of-plane deformation of column flange, moment transfer efficiency of web connection is reduced and this results in reduction of beam plastic rotation capacity. In order to investigate the effects of width-to-thickness ratio (B/t) of RHS column on the rotation capacity of composite beam, cyclic loading tests were conducted on three full scale beam-to-column subassemblies. Detailed study on the different steel beam damages and concrete slab damages are presented. Experimental data showed the importance of this parameter of RHS column on the seismic behavior of composite beams. It is found that occurrence of severe concrete bearing crush at the face of RHS column of specimen with smaller width-to-thickness ratio resulted in considerable reduction on the rate of strain increase in the bottom flange. This behavior resulted in considerable improvement of rotation capacity of this specimen compared with composite and even bare steel beam connected to the RHS column with larger width-to-thickness ratio.
Key Words
    composite beam; rectangular hollow section column; cyclic loading test; rotation capacity; connection factor
(1) Mohammadreza Eslami:
Department of Architecture, Kobe University, Japan;
(2) Hisashi Namba:
Department of Architecture, Kobe University, 1-1 Rokkodai, Nada ku, Kobe, 657-8501, Japan.

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