Study On Wind-Induced Dynamic Response And Equivalent Wind Load Factor Of Long-Span Grid Roof Structures

Along with the development of science and technology,the stands of stadium are often covered with long-span flexible roof structures with beautiful shapes and new structural systems. When wind flows around roofs,the airflow will be separated to form a high suction zone,and the flexible roofs will suffer from wind-induced buffeting response. So far,a limited number of research papers are related to dynamic responses of long-span flexible roofs. Long-span grid roof is a special topic of long-span flexible roof structures,and it is important to study on wind load and wind-induced dynamic response in the field of engineering and research.Based on wind tunnel test and theoretical analysis,the vibration mechanism,vibration shape,dynamic response and equivalent wind load factor of the long-span grid roof of Taizhou Stadium subjected to wind excitation are analyzed systematically in this dissertation,and some valuable results are obtained.In the matter of wind tunnel tests,the distribution rules of roof under various wind directions are obtained through the data got from the wind tunnel tests for rigid model of long-span grid roof of Taizhou Stadium. Furthermore,the isoline maps of mean wind pressure coefficients and RMS wind pressure coefficients of the structure under various wind directions are plotted .In the matter of theoretical analysis,modeling with finite element method,using the local mean wind pressure coefficients and time history of fluctuating pressures determined in wind tunnel,the wind-induced dynamic responses for long-span grid roof structures are calculated in frequency domain and time domain separately. In frequency-domain,the background mode that has the most contribution to the buffeting energy of the structure is calculated using the background modal analysis method,thus the RMS of the dynamic responses of long-span grid roofs is obtained. On the other hand,the RMS of the dynamic responses is also obtained by direct integral method in time-domain. After the comparison of the results of two methods,several important conclusions can be made. The rules obtained from the background modal analysis method based on the quasi-steady assumption in frequency-domain aresimilar to those obtained by the analysis method in time-domain,and the influence of high modes can be considered. Finally,the dissertation suggests that for engineering design,it is better to use equivalent wind load factor defined the ratio of wind-induced total displacement to static displacement for computing the equivalent static wind load of long-span grid roof structures,And the equivalent wind load factor of the roof of Taizhou Stadium is calculated.