Seismic isolation of modular reinforced concrete buildings

Purpose of research. The aim of this research is to develop a constructive solution that ensures the earthquake resistance of a modular building in an area with a seismicity of 9 points on the MSK-64 scale. Methods. The research uses a FEM computational model of a building with a modular structural system with reinforced concrete modules. Numerical analysis was performed using finite element modeling (FEM) in ANSYS and SCAD. A single computational model of the entire building was developed in SCAD, incorporating the monolithic part, modular part, and inter-module connections. The inter-module connections were modeled using special finite-stiffness elements. The stiffness of inter-module connections was determined through a 3D finite element model in ANSYS, which was also used to analyze stress distribution in the connections. The model accounted for all operational loads. In addition seismic loads were used, in compliance with valid Russian design codes for Vladikavkaz. The analysis assumed linear elastic material behavior for all structural components. During the calculations, the intensity of reinforcement in the building's load-bearing structures and the stress distribution in the most loaded inter-module joint are investigated. Results. The calculation results show that the use of seismic insulation significantly reduces the impact of seismic effects on the building, reducing the intensity of reinforcement to 55% (by more than 2 times) in the monolithic part and up to 60% in the modular part compared to a similar building without a seismic insulation system. Additionally, a reinforced inter-module connection design was proposed, which ensures compliance with strength requirements under seismic loading. Conclusion. This study demonstrates that the required level of earthquake resistance is achieved because of the use of a seismic insulation system, thus, constructive solutions can be preserved. This study has an important practical benefit, which consists in preparing the calculation base for the construction of prefabricated modular reinforced concrete buildings in seismic areas. In subsequent research phases, it is necessary to account for the post-elastic behavior of inter-module connections, and the strongly nonlinear response of sliding seismic isolators. This will enable more accurate quantitative assessment of seismic performance calculations for modular buildings with base isolation systems.