Parametric study on module wall-core system of concrete modular high-rises considering the influence of vertical inter-module connections

High-rise modular buildings are attractive for metropolises, but few applications exist. One reason is the lack of relevant knowledge about their lateral force resistance. Existing high-rise modular buildings generally adopt cast-in-situ concrete cores, which can work with precast module walls in concrete modular buildings to resist lateral loads together. This study aims to parametrically examine the module wall-core system. A typical 40-story public residential building in Hong Kong was selected as the case building and re-designed to be a concrete modular building. A method called generalized modulus reduction method was adopted to consider the influence of vertical grouted connections on lateral behavior of slender precast concrete walls. A three-dimensional finite element model using this method was established to study the influence of three parameters on the structural responses of the case building under the Hong Kong code-specified wind loads, which were the module wall thickness, the reduced lateral stiffness of module walls, and the defect distribution scenarios of vertical intermodule connections. Results show that the developed method can well consider the influence of vertical grouted connections. The module wall-core system can provide sufficient stiffness and strength for the case building, and module walls play a leading or even a major role. It is beneficial to increase the thickness of module walls due to reduced site work for core walls without adverse effects on the structural responses of buildings. With the reduced lateral stiffness of module walls, the case building's deflection increases speedily, with more serious wind-induced vibration and more vulnerable core walls. When more defective vertical inter-module connections are concentrated on the bottom stories, there are relatively small impacts on overall structural responses of the case building, while strong adverse impacts on core walls at the corresponding bottom stories. For ensuring safer structural design, the influence of vertical inter-module connections on the global lateral force resistance of concrete modular high-rises cannot be ignored.