Refinement Theory Of Random Wind-Induced Dynamic Response For Long-Span Roof Structures

Long-span space structure symbolizes the scientific and technological architecture level of a country. With rapid development of economy and culture of china, all kinds of beautifully designed and innovative long-span structures are widely used in aviation houses, stadiums, exhibition halls and other public buildings in order to obtain the most large space without interior columns. Because of the characteristics of the wind-sensitive structure, light weight, flexibility, low damping and low frequency, the wind load becomes the main problem of the structure design. With the complexity of long-span roof structures and air flow, still now, a general theory framework of wind load and wind-induced dynamic responses for a common long-span roof has not been established. This dissertation try to study deeply the existing theoretical framework, the methodology of wind loading and wind-induced dynamic responses for a common long-span roof, which tends to be explored in the following aspects: wind loading characteristics and wind tunnel test; wind-induced dynamic response in the frequency domain and time domain; the equivalent static wind loads and structural impact of thunderstorms, and other aspects of wind-induced dynamic responses for the long-span roof structures. The dissertation mainly covers the following categories:1. The study of roof wind loads and wind tunnel test. Based on the characteristics of the wind field in atmospheric boundary layer, some commonly-used simulated methods of wind fluctuation are provided in detail. Different characteristics of the AR method and Shinozuka-Deodatis method are compared, by examples, the surface wind pressures of a long-span aircraft terminal hall are obtained by the rigid model wind tunnel test. Meanwhile, the variable laws of mean and fluctuating wind pressure coefficients on roof surface for different wind directions, the characteristics of mean and fluctuating wind pressure coefficients at main measuring points for different wind directions, and the characteristics of probability distribution and extreme wind pressures at main measuring points have been analyzed in a detailed, and some common characteristics can be seen.2. The study of the wind-induced dynamic responses of long-span roof structures in the frequency domain. Because of quasi-steady assumptions in traditional frequency domain methods and the low efficiency of calculations for CQC method, this dissertation proposes a frequency domain method: obtaining the dynamic wind pressure from the wind tunnel test, and establishing a model of roof wind pressure with the POD method, then the accurate wind pressure spectrum of roof can be obtained by fast Fourier transform of wind pressure spectrum, and the wind-induced dynamic responses can be obtained by pseudo-excitation method. The revised method is more efficient, abandons the quasi-steady assumption and thus the result has higher reliability.3. The study of the wind-induced dynamic responses of long-span roof structures in the time domain. Two methods to obtain the wind-induced dynamic responses of long-span roof structures are brought up. Firstly, the direct use of wind tunnel test data with a combination of multi-modal force method and modal decoupling principle, the multi-modal explicit integration method (MMEIM) is proposed. The method has good stability and high efficiency and is suitable to solve the problem of the wind-induced dynamic responses for long-span roof structures.In order to avoid the matrix iteration of random discrete vibration method, the multi-modal precise integration method for random discrete analysis(MPIMRDA) combined with the model wind tunnel test to estimate the wind-induced response of long-span roofs has been developed. The distribution of the wind-induced dynamic responses and wind-induced vibration coefficient has been studied and compared respectively. And some useful conclusion for the long-span roof structure designing have been found.4. The study of the wind-induced dynamic responses of long-span roof structures based on double POD model. The simulation of the wind field on the roof structures is a fundamental step in the analysis of their wind-induced dynamic responses. But the previous methods can't established the mathematical model of the three-dimensional random wind fields at the same time. Based on double POD model and Monte Carlo method, a very efficient simulation scheme of the three correlated turbulence components is proposed. Utilizing the random discrete theory and the multi-modal acceleration method, schemes for estimating the wind-induced dynamic response of long-span roofs are presented. And the distribution of the wind-induced vibration coefficient on the roof surface are studied as well.5. The study of equivalent static wind loads of long-span roof structures. Using the LRC method and inertial wind loading method, the equivalent static wind loads for long-span roof structures can be determined. In order to overcome the assumption of the SRSS method,which has to be good separation in the background and resonance response,a revised method of resonant response is proposed by introducing a modal coupling coefficient to avoid error caused by the lack of consideration of modal coupling effects. Through two different forms of the arched roof system and the long-span roof system, a detailed studies of equivalent static wind loads for a different roof structure are presented.6. The study of the wind-induced dynamic responses of long-span roof structures to thunderstorm downbursts. Thunderstorm downbursts, which are known that the wind characteristics are totally different with general boundary layer winds, are defined as an outburst of damaging strong winds on or near the ground. When such events occur, the roofs will induce a large buffeting response. A deterministic-stochastic hybrid model to simulate a thunderstorm downburst is presented. Wood's velocity profile for the vertical profile and Holmes' empirical model are utilized to generate the mean wind. The fluctuation is generated by stationary Gaussian stochastic process. A new method is provided to estimate the wind-induced responses of long-span roofs. Using the time histories of downburst wind loads, the dynamic responses of structure can be obtained in the time domain. The distribution of wind-induced vibration coefficient on the roof surface has been studied, and some important conclusions are reached.