| Light steel structure residential system is a structural system which is often used in green buildings.Its form is mostly a frame composed of dense columns and dense beams.Light steel structure is generally used in low-rise buildings with three stories or less.It combines many advantages together easy to standardize and industrialize,such as light weight,high strength,and fast construction speed.In the background of promoting the low-rise light steel houses and accelerating the construction of new rural areas,a new idea was proposed for obtaining a braced frame with better seismic performance to improve seismic resistance and economy of light steel houses.A variety of technical tools were used such as nonlinear time history analysis,equivalent static load,BESO(Bi-directional Evolutionary Structural Optimization)algorithm,APDL(ANSYS Parametric Design Language),to finish the following work:Firstly,the equivalent static load under earthquake action was obtained by the displacement equivalent method.According to the requirements of the specifications,light steel building composed of four unbraced frames were established,which had one to three stories with a column spacing of 0.6m or 1m,respectively.The nonlinear dynamic time history analysis for these unbraced frames was carried out on the condition of 7 and 8 earthquake intensity degrees,respectively.Base on the maximum displacement response obtained by time-history analysis,the horizontal equivalent concentrated static load of each light steel frame under the earthquake action of different intensities is obtained.The results show that the light steel structures composed of four unbraced frame cannot meet the limit of displacement angle limit,and the corresponding concentrated static load can be found according to the maximum horizontal displacement generated by the seismic effect.Secondly,the braced frames were designed by topology optimization under equivalent static load.The optimization took stress homogenization as the objective and finite elements as the design variable.In the optimization,the horizontal equivalent load and the vertical uniform load are combined as the load condition of topology optimization.Using the BESO method to optimize a dense column frame,a braced frame suitable for low-rise light steel residential buildings was obtained,which has uniform stress distribution and excellent seismic performance.The results show that the frame obtained by BESO optimization has uniform stress and efficient supports;when the frame resists the horizontal force,the supporting distribution form will fluctuate near a certain optimal structural form.Thirdly,the dynamic performance of the optimized structure was tested by numerical analysis.Taking the horizontal displacement of vertices and the displacement angle between stories as performance indicators,the seismic performance of the optimal braced frame,the braced frame designed by the structural concept and unbrace frame are compared by nonlinear dynamic time history analysis.And the seismic performance of optimal braced frame designed by BESO were verified by simulating the engineering application in light steel residence.The results show that the braced frames optimized by BESO have superior seismic performance and high economy compared with the unbraced frames and braced frames by the conceptual design;the four-steel light steel house with supporting frame can well meet the requirements of the interlayer displacement angle limit.Finally,a layout scheme of braces to improve economic efficiency under the premise of ensuring structural performance is proposed.To obtain light steel residential frames with excellent seismic performance and cost-effectiveness can be obtained by reducing the number of optimal braced frames in light steel houses and changing the placement of braced frames.The results show that the requirements of economy,efficiency and safety can be achieved by reducing the number of supporting frames and arranging the positions of supporting frames reasonably. |
PDF Full Text Request