A hybrid inter-module connection for steel modular building systems with SMA and high-damping rubber components

Abstract

The recent technological advancements achieved in modular construction have accelerated the trend of building taller self-standing steel modular building systems (MBSs), leading to a consensus among researchers regarding the vital role that inter-module connections (IMCs) play in the structural performance of MBSs subjected to extreme lateral loading. However, existing IMCs are typically designed such that the global structural system heavily relies on the hysteresis of the steel framing members, leading to severe sustained damage and costly, impractical retrofitting programmes. To unlock the full “disassembly and reuse” potential of steel MBSs, IMCs can be designed to contribute more effectively to the global damage distribution mechanism, by engaging specific “fuse” components which are easy to replace, improving the reuse prospects of volumetric modules. In this regard, the present study proposes a novel, hybrid IMC using custom corner fittings, a high-damping rubber (HDR) core and a shape-memory alloy (SMA) bolt. Calibrated and validated material models using data from experimental material characterisation tests have facilitated the full characterisation of the hybrid mechanical response, determining the deformation modes, stress states, hysteresis loops and mechanical parameters. The parametric FEA included the variation of bolt preload, endplate thickness, axial load magnitude and the vertical layout of the HDR core. The study represents a preliminary, proof-of-concept investigation, showcasing the favourable cyclic performance of the proposed IMC under the main deformation modes expected in tall self-standing MBSs during lateral loading. Due to the effective contribution of each component to the combined hybrid response, the connection succeeds in preventing the formation of significant plastic damage in the MBS’s corner fittings to facilitate reusability of modules.