| The development direction of modern public buildings is the aesthetics,novelty and function diversification.The large chassis multi-tower structure has become the main structural form of modern urban complex buildings.In order to meet the requirements of space sharing and aesthetic effect,the design of complex transfinite structure is a common challenge to engineers.Therefore,it is necessary to carry out the structural design and research of the over-limit high-rise buildings.In this paper,takes an ultra-long slant column double tower structure of a chassis in NanChang as the object.Two kinds of elastic seismic analysis are used to analyze the seismic design under the action of multiple earthquakes.In addition,the static and dynamic elastoplastic analysis methods are used to calculate and analyze the seismic action of the structure in rare earthquake.Due to the discontinuity of floor slabs,large hole opening and local weak connection,floor stiffness of chassis structure is weakened and structural integrity is poor.In order to avoid the design insecurity caused by unreasonable calculation assumptions of the structural analysis(the maximum difference of reinforcement is 35%),the two towers are modeled and analyzed separately in this paper,and compared with the calculation results of the overall model of large chassis and twin towers,the structural design(reinforcement)is based on the envelope design of the overall model and the sub-tower model.Due to the common design software analysis because of the inclined column beam axial force is difficult to achieve,also can't accurate analysis when super-long structure designed floor reinforcement stress,which is based on egenerated three-dimensional solid virtual laminated element nonlinear finite element analysis method(VFEAP)is simple and easy,cell division can consider beam plate column wall space together,can accurate read each advantages of the root stress of the steel.In this paper,VFEAP is used to analyze the spatial cooperative force of beam and plate column wall of inclined column structure unit under vertical load.The results show that the inclined column is in the state of eccentric compression,and the upward stress is decreasing,while the beam plate at the top of the inclined column is mainly under tension.Through the simulation analysis of different slab thickness and different slab reinforcement,the results show that increasing the slab thickness is not obvious to crack control effect after concrete cracking,while increasing the slab reinforcement can effectively control its crack width,and it is more economical and reasonable to increase the slab reinforcement ratio to+0.4%?+0.6%.It is an attempt and innovation to study the influence of PMSAP and VFEAP on the floor temperature stress in large cantilever area.The cantilever model was studied by using VFEAP,considering the spatial coordination of beam,plate and column,and using PMSAP to determine the boundary constraint condition of the model.The concepts of concrete shrinkage equivalent and seasonal temperature difference are introduced,corresponding boundary constraint conditions and floor loads are applied to the cantilever model under different temperature conditions to simulate the deformation characteristics of the structure.The results show that the floor tensile stress on concentrated around the vertical members.The development of the crack is roughly the same as the main tensile stress distribution of the floor,and continues to develop along the X and Y directions with the increase in temperature difference.According to the calculation results of crack width of normal use,the crack width of floor slabs in large cantilevered area can meet the requirements of the specification.This study provides some ideas of strengthening some key performance points of complex transfinite structures and provides references from the design of similar structures in the future. |
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