Module equivalent frame method for structural design of concrete high-rise modular buildings

Abstract

Despite the increasing adoption of modular construction worldwide, it is still largely limited to low-to-medium-rise buildings. One of the main reasons is the knowledge gap regarding the structural design of modular high-rises. This provides a significant opportunity for research and development as high-rise buildings are more competitive in metropolises. This study aims to develop a novel module equivalent frame method (MEFM) for structural design of concrete high-rise modular buildings based on the concept that modules bear vertical loads and transfer lateral loads to cores that mainly resist such loads. A typical Hong Kong high-rise public residential building was used for the case study. The modular structural design scheme was considered as the case study building based on three aspects, i.e. floor plan, connection types, and modular components. A new procedure was established to determine the strength grades of module walls for unifying their thickness at different stories while satisfying the structural performance. An analytical method was established to determine an equivalent frame system with significant vertical resistance and limited lateral resistance to model the walls within a concrete module according to the equivalent principle of concrete volume, size, and shape requirements. The structural responses of the 30-, 40-, and 50-story cases under wind load were calculated using the developed MEFM and compared with the results using the ‘equivalent shear wall method’, which considers the module walls as shear walls. Results show that the MEFM is feasible for achieving structural design solutions of concrete high-rise modular buildings. Moreover, the MEFM is found to be more suitable for the 30-story case than for the 50-story case owing to the reduced precast ratio with an increase in building height. Furthermore, the MEFM is more appropriate than the equivalent shear wall method for simulating module walls because it can better balance the structural safety, material consumption, and precast ratio. The procedure for determining the strength grades of module walls can reduce the lifting weight owing to the higher strength concrete used in the module walls at lower stories. The proposed modularisation scheme is typical and representative and can be adopted for standard flat types of high-rise public residential buildings in Hong Kong.