Study On The Seismic Behavior And Seismic Response Reduction Of Stadium Canopy Structure

Stadium structure with cantilever roof is so complicated that it's hard to be designed. At present, home and abroad scholars pay more attention to the response of cantilever roof structure under the wind loads and the vibration on the floor which caused by crowd moving human loads, and the seismic responses are little to be concerned relatively. Based on the shaking table experiment of Jinan Olympic Center and finite element analysis, the seismic performances of cantilever roof structure were deeply studied. Attempt of setting the displacement-type mild steel damper (HADAS) on the structure, the responses under seismic excitation were controlled, and it effectively reduced the seismic response.A shaking table test of a 1/20 scale model of the Jinan Olympic Center was carried out. The model's dynamic properties, damping ratio and seismic responses under different earthquake levels were studied. During the test, the vertical seismic responses of cantilever roof structure were specially analysised. By measuring the key point's displacement,velocity and acceleration responses, the phenomenon that the seismic effects on cantilever roof structure which with high supports were amplified over 10 times in the vertical direction was revealed, and it guide the design to focus on the improvement of the strength requirement of cantilever roof structure's supports.Finite element analysis further revealed the laws of the seismic responses, and they were in good agreement with the shaking table test results. A sequence of generating hinges was studied by horizontal and vertical elasto-plastic analysis, and the structural seismic performance was further evaluated by capacity spectrum method. Because the cantilever roof structure was sensitive for the vertical ground motion, the vertical multi-model combination nonlinear static analysis method had been established. The contribution of higher modes was specifically taken into account, and the results show that the use of traditional single-modal loading mode method will obviously lead to unsafe results. Therefore, the multi-modal method is recommended for the vertical static elasto-plastic analysis of canopy structure.The pseudo excitation method was further improved and used for multi-dimensional random seismic analysis of the cantilever roof structure. Theoretical formulations for multi-dimensional pseudo excitation algorithm were derived. A method of evaluating average peak responses was recommended. Seismic random models and parameters under multiple seismic ground motions were detailed introduced. The displacement responses of key nodes under single dimension and multiple dimensions were compared by calculating. The structure response under multi-dimension seismic input would be significantly magnified. The results of pseudo excitation method and the time history analysis were compared to verify the accuracy of multi-dimensional pseudo excitation method, and they were in good agreement. Multi-dimensional pseudo excitation method as an efficient random vibration analysis method provides an effective way to the field of random vibration analysis of large-scale stadium structure with cantilever roof.Nonlinear time history analysis on the modal structure with displacement-type mild steel damper was carried out. Compared with the plastic responses results of the two structures (with and without damper), no matter the appearance of plastic hinges, or the seismic response of members, even the hysteretic curve of dampers on different positions, all indicate that dampers effectively absorbed part of ground motion energy which passed to the structure, and reduced its seismic response. By simulation analysis, the energy dissipation effect of cantilever roof structural with displacement-type mild steel damper were verified, and it provide a reference for the future design of energy dissipation wiith similar structures.