Interaction of the rocking steel interconnection with intra-connections in a moment resisting modular joint

The structural behaviour of modular joints in prefabricated prefinished volumetric construction (PPVC) can be highly influenced by the interactions between interconnections (module-to-module) and intra-connections (beam-to-column). A joint featuring a novel Rocking Steel Interconnection (RSI) has recently been developed, and experimental investigations of its interaction with a single intra-connection have shown promising results. However, the behaviour of the RSI when engaged with two intra-connections has not yet been investigated. To address this, the present study conducted a full-scale cyclic test on a specimen incorporating an RSI and two intra-connections. Subsequently, a numerical model was developed to assess the effects of key parameters governing this interaction, including beam size, axial load, and beam length. The experimental results revealed a wide hysteretic response attributed to plastic hinge formation at the intra-connections. The presence of the ceiling beam redistributes the moment, reducing the demand on the RSI. The FE parametric analysis further demonstrated that the ratio of floor beam to ceiling beam sizes in a joint plays a critical role in distributing moments among the connections. The axial load also improves the joint performance till it does not exceed the column compressive buckling capacity. Nevertheless, using shorter beams could alter the sequence of failure modes and interfere with the axial load efficiency.