Elasto-plastic behavior of composite beam connected to RHS column, experimental test results

This paper presents results of study on the elasto-plastic behavior of composite beam connected to Rectangular Hollow Section (RHS) column in the steel moment resisting frame buildings. 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 test were conducted on three full scale beam-to-column subassemblies. Detail study on the different steel beam damages and concrete slab damages are presented. Experimental test showed the importance of this parameter of RHS column, on the seismic behavior of composite beam. 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 lower 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.