Topology Optimization And Style Selection Study Of Transfer Slab

Transfer slab have powerful conversion capability, especially suitable for structure with complex style and various function, but the great weight of the transfer slab, not only the strength requirements of the vertical structural member below the slab is increased, but also the vibration performance of the entire structure is extremely complicated and prone to damage. In this dissertation, based on large-scale general software ANSYS, with its own language APDL for the secondary development tools, use of evolutionary structural optimization method for the transfer slab topology optimization to reduce its weight and improve the seismic performance of the overall structure. Two new slabs were proposed according to the optimization results, and its mechanical performance and cost-effectiveness were analyzed. The main research works of this dissertation can be summarized as follows:(1) according to different research purposes, the corresponding calculation and optimization command stream were programmed, in addition to the conventional function of ANSYS, some advanced technology such as submodel technology, element life and death and macro files also used.(2) Structure optimization based on static force were done for a project example, the selection of stress criterion for anisotropic materials such as concrete were studied in evolutionary structural optimization method, and the modified Balanjin theory were proposed to measure the stress level of elements, further to guide optimized to carry out. For the FEM calculation of actual project, the miscellaneous element types and large calculated amount of node displacement, an element displacement sensitivity computational method were proposed, element strain energy and element displacement of specific direction were introduced in this method, and it is particularly convenient in general FEM software. Force transfer path of transfer slab were obtained according to the static optimization results of the example.(3) Two goals were proposed of structural dynamic optimization:frequency optimization made natural frequency of structure far away from excitation frequency, so as to avoid resonance; structural optimization under moving loads to ensure structural internal force and displacement in the allowed range by the action of moving loads. To the example of this dissertation, respectively, to select frequency of first-order lateral bending of two principal axis and first-order torsion and do the frequency optimization, by changing the topology of transfer slab to make the structural low-order frequency keep away from the predominant frequency of ground. Element sensitivity formula were derived using mode analysis response spectrum method calculate earthquake effect, the sensitivity formulas are different when using different methods to estimate the biggest reaction of system, this method is suitable for engineering topology optimization self-programming. A new method introducing internal force result after modal combination to calculate the dynamic sensitivity were proposed, this method is suitable for general FEM software which can calculate earthquake effect by mode analysis response spectrum method. Force transfer path of transfer slab were obtained according to the dynamical optimization under earthquake effect of the example.(4)Two new slabs local thinning nonuniform transfer slab and steel-concrete composite open-web transfer slab were proposed, and let the original transfer slab comparison with two new slabs in static analysis, focus on transfer slab and the load-carrying capability of vertical structural member below the slab. To local thinning nonuniform transfer slab,16 kinds of thinning program were designed according to the removing block with different size and position, and comparative analyses the result of each programs, the effect to vertical structural member below the slab and transfer slab were studied when the size and position of removing block are different. To steel-concrete composite open-web transfer slab, in particular, internal forces of steel frame and shear connectors were analyzed, and give some suggestions for treat with of shear connectors.(5)Let the original transfer slab comparison with two new slabs in modal analysis, focusing on the law of mode shape from 1 to 30 stages. Mode analysis response spectrum method and elasticity time-history method were used to calculate earthquake effect for three structures, and the result of time-history analysis adopt envelope of the maximum value. To the high-rise structures with different transfer slab, respectively, comparing the response spectrum and time history analysis results of two main principal axis direction, and discuss the result differences of two analytical methods. Comparison of response spectrum analysis result of three structures and time history analysis result of three structures, and discuss the change of load-carrying capability of high-rise structures with new transfer slab.(6) Let the original transfer slab comparison with two new slabs in direct and indirect economic benefits qualitative.