Research On The Wind Loads And Wind-Induced Vibration Response Of Large Roof Structures

Recent years, large span roof structures are extensively adopted in public places internal and overseas. This kind of structure has two characters, light mass and small damping. It is always in low atmospheric boundary layer , its wind-induced vibration response is very marked and its wind disaster occurred frequently, so the wind-resistant research and design of this kind of structure become more and more urgent. But the data about its location and whole structure's dynamic wind load is quit little in structure wind load code, and the theory study is in groping phase. At present, the main method to solve this problem is wind tunnel model test combined with computer calculation. In this paper, the wind tunnel test of large span roof structures' dynamic wind loads have been discussed systematically, the modal decomposition method and time domain method, which was combined with the result to calculate the wind-induced vibration responses and equivalent static wind loads of (non-large-deformation) large span roof structures are also studied at the same time, and some engineering-valuable conclusions are summarized.The exact simulation of atmospheric boundary layer is not only the precondition of the wind tunnel test of the large span roof structures, but also a difficulty of its. After absorbed much great design experience from China and foreign countries' literatures, the D kind boundary layer in the GB 50009-2001 code was successfully simulated in this paper through the passive simulation technology based on battier, spires and roughness elements, which is quit simply and economical. It was satisfied to intensify the top turbulence intensity, longitudinal integral length scale of the atmospheric boundary layer and the energy of low-frequency turbulence by adding transverse spring boards on the spires, this method also can be referred to other simulation of atmospheric boundary layer.The Adjusting of the test system and the developing of the data-processing system are also the basic work for the fluctuating wind pressure wind tunnel test on Large roofs. Firstly the frequency-response quality of various pressure tube systems is tested in this paper and the test results are compared and analysed, so the fluctuating wind pressure wind tunnel test system based on the most advanced scanivalve system is established in CGB-1 wind tunnel. By the CAARC test it is validated that the test system has a high reliability. Simultaneously the statistical character of the the fluctuating wind pressure is analysed, the objective-probability method to calculate the peak pressure factor is put forward, and by using it the appropriate guarantee- probability can be easily chosed in the actual anti-wind design of building projects.In succession, the data-processing system for the fluctuating wind pressure wind tunnel test on Large roofs is developed by using VB6.0 combined with AUTOCAD2002,MATLAB6.5 software.This system has a interactive interface, it can be expediently used by the test researchers to prepare the test and check the test data and put right, it can educe the text files and drawing files which are easily used for actual building projects.Lastly, the formulas of modal decomposition method and time domain method combined with the time-history data of the fluctuating wind pressures are deduced to calculate the wind-induced vibration response and Equivalent static wind loads of Large roofs. An actual example is given in this paper, and the analysis of it's result shows: the computing precision of the time domain method is higher than that of the modal decomposition method, but time-consuming; for the modal decomposition method, the more modes participate in the calcalation, the more higher precision the results have, but this effect is not obvious when over 50 modes. It can improve the computing results' precision through following approaches: synchronizing the time-history data of the fluctuating wind pressures by in-phase, eliminating the bad error of this data by using five-point-third-power smoothing method in time domain method, smoothing the fluctuating displacement spectral curve by multi-point method and taking into account the crossed items of mode transfer functions in the modal decomposition method.