Development of efficient structural systems for mid-rise modular steel buildings with pre-loaded inter-module connections

Abstract

Modular construction has many advantages, such as construction speed, associated cost savings and reduction of waste. So, the demand for steel-framed mid- and high-rise modular buildings in urban areas has rapidly increased, including in seismic areas. Structurally, in order for the many individual modules to behave stably as a compatible building, the inter-module connections are most critical. The connection should be sufficiently rigid, and its installation also needs to be as easy as possible.

This thesis proposes an innovative post-tensioned type inter-module connection (AJ connection) that maximises construction speed and reusability of modules for mid-rise steel-framed modular buildings that can be applied in seismic areas. This connection connects modules vertically by preload using the developed coupler and high-tensile steel rod bolts within columns. Its simple shape and installation process for connecting modules provides an easy and convenient on-site assembly and disassembly process, minimising site work.

The AJ connection was investigated using analytical, experimental and numerical methods to provide optimal design principles and structural modelling of the connection, enabling engineers to design the connection in practice. First, the thesis establishes a design method to determine the minimum demand preload for the connection. Then, the structural performance of the connection was evaluated by full-scale joint tests and finite element 3D joint models. The AJ connection exhibited similar performance to welded connections and therefore can be simply modelled as fixed connections for structural analysis under the assumption that the demand preload will be induced in the connection. Conclusively, the performance of the connection was verified to have sufficient performance for mid-rise steel-framed modular buildings in both seismic and non-seismic areas. Based on these studies, guidelines for the optimal design of the AJ connection were developed.