Numerical simulations to explore the in-plane performance of discontinuous diaphragms in modular steel buildings

As a new type of building system, modular steel buildings (MSBs) use a unique construction method; obvious discontinuities exist in modular diaphragms, making them quite different from traditional ones. To investigate the in-plane behavior of discontinuous diaphragms, numerical investigations were conducted using both refined finite-element (RFE) models and simplified modeling methods. First, the RFE models were established and analyzed, and their results were compared with experimental data. The nonlinear properties of the intermodule connections were determined based on the sub-models obtained from the validated RFE models. Subsequently, simplified models of the assembled modules with discontinuous diaphragms were created and used to investigate the in-plane load transfer performance. Through numerical investigations, the discontinuous diaphragms were found to not satisfy the rigid floor assumption; the effects of different horizontal connections and upper-floor structures on the discontinuous diaphragms were also analyzed and discussed. The simplified models presented load-displacement curves and displacement distributions very similar to those of the RFE models. Moreover, one analytical model was proposed and discussed based on the simplified models, then a positive correlation was found between the lateral stiffness and displacement distribution of the assembled modules. The proposed simplified modeling method can be an effective tool for studying discontinuous modular diaphragms and their effects on the structural response of MSBs.