A macro element of demountable bolted steel-concrete composite connections for a novel prefabricated concrete sandwich wall panel structure

Abstract

A novel prefabricated concrete sandwich wall panel structure (PCSWPS) system has been proposed for low-rise buildings in rural areas in China. The wall panels are jointed using high-strength bolts and steel plates through bolted steel-concrete composite connections (BSCCs). Despite published experimental results showing promising seismic performance of the structural system, the mechanics governing the interaction between the bolts, steel plates, and concrete at the connections still need to be clarified. To this end, we carried out full-scale connection experiments and finite element (FE) analysis to investigate the uniaxial tensile characteristics of the connections to simulate their working conditions in seismically loaded structures. It is shown that the tensile load-transfer mechanism through a BSCC is closely related to two frictional sliding responses and a compressive contact behavior. Based on the experimental data and FE results, a macro element was proposed to simulate the mechanical behavior of BSCCs. The macro element is able to model the interactions between the bolts, steel plates, and concrete separately using springs, assembled in series and/or in parallel in a composite manner. In particular, the loss of bolt clamping forces and ultimate tensile capacity of the connection are well captured by the macro element. Finally, the macro element was validated against existing experimental data on bolt-connected shear walls using OpenSees. It is believed that the clear load-transfer mechanism can be beneficial for the design of PCSWPS, and the proposed macro element can facilitate seismic analysis of PCSWPS without the need of a detailed connection FE model.