Wind-Induced Response And Equivalent Static With Load Of Long-span Roofs: Theoretical Research And Application

With their beautiful shapes and excellent performance, long-span roofs have been widely applied for various large public buildings, but the theory of wind-induced vibration and equivalent static wind load of long-span roofs has not been well developed yet. The lack of such theory will make the roofs either in danger or wasteful. In order to provide a systematic method to research the wind-induced vibration and equivalent static wind load of such structures, the pseudo-excitation method and mode-superposition method are employed in this thesis. The research is mainly focused on the following aspects:1. Accurate and high efficient computing methods of wind-induced buffeting responses of long-span roof structures. Both the traditional pseudo-excitation method and CQC method ignore the contributions of high-order modes to the background component of the wind-induced response completely. Sometimes this will cause obvious errors. Based on the pseudo-excitation method and mode-acceleration method, a new computing method named modified pseudo-excitation method is proposed, which is theoretically accurate and high efficient. Then a dynamic computing program is developed based on the proposed method and self-adaptive quadrature method. Using the program, the following aspects are discussed carefully, including: (1) the cross terms of all computing modes; (2) the traditional pseudo-excitation method and the modified pseudo-excitation method; (3) different wind speed (pressure) spectra; (4) different coherent functions and decay factors; (5) the quasi-steady method and non-steady method; (6) the upper boundary of the quadrature. Through these discussions mentioned above, the accuracy and efficiency of the theory and program are validated, and the influence of these aspects to the result of the computation is properly understood.2. Research on constructing reasonable computing modes. Although the modified pseudo-excitation method is accurate on theory, it is relatively less efficient compared with the traditional pseudo-excitation method. The latter can also get a correct result through reasonably selecting a group of computing modes. Considering the reasons mentioned above, the mode-contribution-factor is proposed to identify and select the fundamental mode of the structure and all other modes contributable to the wind-induced response, and the cumulate mode contribution factor of the selected modes is defined to judge the reasonability of the computing modes. According to the order of the fundamental mode in the mode series, the structures can be classified as two different categories, and the opposite influence of the space coherence of the wind to the two structures can be found. Furthermore, two methods are proposed to improve the reasonability of the modes chosen for the mode-superposition method. Together with the mode-compensation method based on the displacement of the mean wind, the three...