Wind-Resistant Study On Long Span Roof

Due to theirs beautiful shapes and capacities of providing huge space without inner columns, long span roofs have been greatly constructed recently as large-sized public buildings such as airport terminal buildings and stadiums. When long span roofs tend to more flexible and light, the wind loads, among all kinds of loads, become dominating. But the theory of wind-induced response and Equivalent Static Wind Load (ESWL) on long span roofs isn't well developed and in most countries few Codes are presented to regulate the dynamic wind loads on long span roofs. Considering such embarrassed condition, the present study puts forward two theories, which is Standard Solution and Model Solution, to obtain the wind-induced response and ESWL on civil engineering buildings. By applying the above-mentioned two solutions, the wind-induced dynamic problems on long span roofs can be solved. And the characteristic of wind pressures on long span roofs is also investigated.Usually long span roofs can be categorized as closed and open type regarding whether their inner surface suffers from wind directly or not. According to these different types, different ways of wind runnel test are given to obtain the wind pressures on long span roofs. And the characteristic of wind pressure distribution on each type of long span roofs is discussed with regard to the roof shapes. The interfering effect and ways to reduce the wind pressures on roofs are also investigated in present study.The Standard Solution is put forward to obtain the wind-induced response and ESWL on civil engineering structures. Here the methods of Covariance Analysis and vibration analysis are employed to obtain the background and resonant component of wind-induced response. And the methods of Load-Response-Correlation and inertial force are used to obtain the background and resonant component of ESWL. When the background and resonant components are derived, the total response and ESWL can be calculated based on the proportions, which indicate the participating degree of the corresponding response. The Standard Solution is employed to solve the wind-induced dynamic problems on long span roofs, which is categorized as beams supporting type and structurally integrated type according to their dynamic properties. After analyzing the common examples of wind effect on long span roofs, it can be found that the background component occupies prevailing proportion of the totality,while the resonant component only occupies small proportion.The Modal Solution, which is based on modal dynamic analysis, is presented to obtain the wind-induced response and ESWL on civil engineering structures. The contribution of modal cross-correlation items is considered as background component, while that of modal non-cross-correlation items is separated as background and resonant component. After summing up the background component in these two items, the background and resonant components of wind-induced response and ESWL can be decided. The Modal Solution is applied to obtain the wind-induced response and ESWL on beams supporting roofs. As for wind-induced response, the accordance will be found between the results of the Standard Solution and Model Solution. As for ESWL, the results of the Model Solution are just an approximation and tendency of those obtained from the Standard Solution. When higher mode is taken in the Model Solution, the smaller disparities can be predicted between the results of these two Solutions. When applying the Model Solution to structurally integrated roofs, the accordant results will be found for wind-induced responses and the large disparity will be found for ESWL.A new method, which is the Load-Lift-Correlation (LLC), is put forward to simplify the calculation on ESWL of background response. Compared with LRC method, the LLC method has virtues of briefness in calculating and definitude in physical significance. And the LLC method also can unify the wind load equations for main structure design and shielding system design.