Preliminary Study on the Cyclic Response of Welded Joints with CHS Beams and Through-All Plates

The use of circular hollow section (CHS) members as columns of moment-resisting frames is limited by the complexity related to the realization of beam-to-column connections. Nevertheless, the recent use in the field of civil engineering of the Laser Cutting Technology (LCT) has offered the opportunity to manufacture welded connections by properly cutting the tubular profile with the imprint of the cross-section shape of the double-tee member. Such a solution is an improved alternative of the joint with the I-beam simply welded to the external surface of the hollow profile since higher flexural strength and stiffness can be provided. This type of joint has an enhanced behaviour due to the higher stiffness of the source of the deformability. To evaluate the effective contribution provided by each component, this research activity has dealt with the study of the cyclic behaviour experienced by welded connections between CHS tubes and through-all plates, since this component is intended to be representative of the actions applied on the tube by each of the beam flanges of a double-tee profile. The work comprised the accomplishment of three cyclic tests on specimens representative of realistic geometric configurations of CHS to through-all plate joints. Subsequently, a finite element model, representative of the analysed connections, has been developed and validated against the experimental results, and it has been exploited to perform numerical analyses of other 44 CHS to through-all plate configurations. The obtained force-displacement curves have been used to calibrate and predict, through analytical formulations, the parameters of the hysteretic uniaxialmaterial element belonging to the OpenSees library.