Numerical simulations on high strength bolted shear connections for simple on-site assembly of composite beams

Abstract

In composite beams, shear connectors are essential to transfer the interfacial forces between concrete slabs and steel beams to guarantee these two components work integrally. The latest research trend is to develop simple on-site assembly of composite beams using demountable shear connectors so that both the steel beams and the concrete slabs are prefabricated in a factory, and then delivered to site for assembly. In general, this construction method will significantly reduce manpower demand, and construction time and costs. A pair of high-strength large-diameter bolts together with a steel block welded onto a steel beam, i.e. Connection RBN, together with precast concrete slabs is proposed by the authors for simple on-site assembly of composite beams, and this paper presents a systematic numerical investigation into structural behaviour of the proposed shear connections. Based on an extensive experimental investigation into a total of 16 shear connections with the proposed connections, advanced finite element models were developed and calibrated against test data. Comprehensive parametric studies with 48 models of the proposed shear connections were then performed with various dimensions and grades of bolts, steel blocks, concrete blocks and precast concrete slabs to examine their effects onto the structural behaviour of these shear connections. In addition, the numerical results were thoroughly analyzed to provide essential understanding for development of load transfer mechanisms within these shear connections. It should be noted that the proposed shear connections behave as twin shear connections according to their possible failure modes taken place in the steel bolts, the concrete blocks and also in the concrete slabs. Moreover, a complementary design method is developed for accurate prediction on the shear resistances of the proposed shear connections.