Research On Wind-induced Vibration And Equivalent Static Wind Loads For Long-span Roof Structures

Long-span roof structures are composed of facilities of different structures and shapes, with the characteristics of light weight, large flexibility, small damping, closed natural frequencies and so on. Hence their wind load distribution, wind-induced vibration analysis and equivalent static wind loads are unique. In this article, based on the theory of random vibration, wind tunnel test and engineering projects, wind-resistant types classification criterion was given for long-span roof structures, also Simplified-CQC and Consistent-LRC methods were proposed for wind-induced vibration and equivalent static wind loads, finally universal equivalent static wind loads research was conducted. The main contents are as follows:1. Long-span roof structures and their wind resistance analysis method were reviewed. Based on the systematical summary and comparison for surface wind loads, wind-induced vibration and equivalent static wind loads of the long-span roof structures, the advantages and disadvantages of each method and application requirements were pointed out. In view of deficiencies and improvement of the wind-resistant research, the needed research work was extended.2. The wind tunnel dynamic pressure test of a long-span roof structure was taken as an example. The principle and data processing method for wind tunnel test were introduced. In addition, the structure modal force spectrum calculation formula was given to facilitate frequency domain analysis of structral respinses.3. Wind-resistant types for long-span roof structures were classified systematically considering the differences of characteristics, the sensitivity to wind, and the wind vibration analysis. The concept of guarantee rate was defined, and according to the proportion of average response, background response and resonant response, wind-resistant types were classified into four kinds. For any type, the corresponding wind-resistant analysis method will be choosen, which can make a better compromise between the efficiency and accuracy.4. The resonant SCQC method of long-span roof structures considering modal coupling effects was presented. The response variance calculation formula was given, which can consider the response variance contribution by modal coupling effects through simple summations instead of complex integration. Hence the calculation efficiency was greatly improved. Furthermore, the process of deducing the formula of simplified for long-span roof structures is reasonable, the calculation precision is also warranted.5. The CLRC method for wind-induced vibration and equivalent static wind loads of long-span roof structures was presented. The CLRC method can be adapted to any wind vibration response calculation method, and the key is to get generalized recovery force covariance matrix. Especially for the need to simultaneously consider the background component and the resonant component structure, modal coupling effects were included in the CLRC method. At the same time, by solving the generalized recovery force covariance matrix respectively, thus the calculation efficiency is much higher than that of CQC method.6. Based on the analysis of the past universal equivalent static wind loads, a new method of universal equivalent static wind loads was addressed. In this method, the generalized recovery force mode was selected as the basic vectors, and a set of constraint equations and weight factor was introduced. Using the least square method, optimal combination coefficient for the basic vector can be obtained. The method not only solves problems of the universal equivalent static wind loads, but also ensures that the equivalent static wind load distribution be more reasonable.Finally, the main research results were summarized, and further research work that will be carried out was discussed.