Structural Design of Xumi Mountain in the Second Phase Project of Zhejiang Buddhist College

The second phase project of Zhejiang Buddhist College is a large religious building constructed with modern architectural language. Xumi Mountain and Doushutian Palace are the core parts of the project. Xumi Mountain is a concrete shear wall structure with a cylindrical shape and a height of 56.85 m. A large platform is set on the top of Xumi Mountain, which is composed of 24 plane cantilever trusses. The maximum cantilever size of the truss is 22.5 m. The root of the cantilever truss is supported on 24 steel reinforced concrete columns arranged in a circular direction. Doushutian Palace is a steel frame structure with a height of 33 m. Its outermost steel column is vertically transformed by concrete ring beam, the middle steel column is connected with Xumi Mountain concrete cylinder through concrete corbel, and the innermost steel column falls on the long-span steel beam. The lower part of the project adopts concrete shear wall structure, while the upper part adopts steel frame structure. The stiffness difference between the upper and lower parts is large. It is a complex mixed structure, and has the characteristics of cantilever, conversion, floor opening and so on.
The project seismic acceleration is taken as 7 degree (0.1g), damping ratio is 0.05 for concrete, 0.03 for steel structure. The site characteristic period is 0.20 s, the maximum value of horizontal seismic influence coefficient is 0.08, and the vertical earthquake is selected as 0.65 of horizontal seismic influence coefficient. The seismic grade of concrete shear wall is grade 3, and that of steel structure is grade 3.
The whole model of Xumi Mountain and Doushutian Palace and the sub model only considering Xumi Mountain were calculated. The analysis results showed that the calculation results of the sub model were quite different from the overall model, and it was difficult to consider the interaction between steel structure and concrete structure in the sub model calculation. In order to ensure the safety and reliability of the design, the whole model and the sub model should be used to calculate and design according to the envelope force.
The Xumi Mountain platform is composed of 24 plane cantilever steel trusses. The calculation results showed that the cantilever truss had large stiffness and high comfort. The first-order out of plane elastic buckling load coefficient of the cantilever steel truss could reach 19.1. According to the installation requirements of curtain wall, three rigid tie bars were added, and the overall stability of the cantilever steel truss met the requirements. In order to ensure the safety and reliability of stress under strong earthquake, the method of adding concrete ring beam to the root of cantilever steel truss was adopted to strengthen the structure.
The small earthquake time-history analysis, fortification intensity earthquake and rare earthquake analysis were carried out. It showed that the seismic performance of the structure met the elastic requirements of fortification intensity earthquake, and the displacement angle between the lower layers of the structure met the requirements of the code. Only part of the members yield under the strong earthquake. The section of some yield members was increased, and the concrete beam with the transfer part bearing Doushutian Palace was strengthened by increasing the section and reinforcing bars.