Investigation On Wind-induced Effects And Equivalent Static Wind Loads Of Large And Complex Structures

As the representative of large and complex building structures, tall buildings and long-span roof structures characterized by light weight, large flexible and small damping are controlled by the wind loads in the design. The refinement of the wind induced responses and equivalent static wind loads on such wind-sensitive structures is of significant importance to the practical design. Therefore, utilizing representative multiple point synchronous scanning of pressure on structure models and taking the complex geometric shape tall building and large roof structure as the main objects, the following aspects of work were carried out in this paper:1. The three-dimensional wind load effects of the single or groups of tall buildings were investigated. For the single tall building with complex geometric shape, the concept of the torsional equivalent couple was introduced to be compared with the value of the corresponding lateral wind loads and the importance of the torsional effects for this kind of buildings was verified. The normalized power spectrum density of the torque wind load for the irregular cross-section in typical wind direction was fitted and the result shows that it is closely related to the parameter of the thickness-width ratio. For the interference effects on groups of tall buildings, taken one group of the linear spaced tall buildings as an example, the distribution and variation of the wind pressures and the three-dimensional layer wind loads on the interfered building surfaces in the key orthogonal wind directions were investigated. It is indicated that the interference effects between the buildings main express as the channeling effect and shielding effect.2. The calculation methods and influencing factors of the wind induced responses of tall buildings with irregular geometric shapes in the three-dimensional spatiotemporally varying wind loads were researched. Based on the linear distribution assumption of generalized force spectrum distribution with the frequencies in logarithmic coordinates, a new simplified formula for the resonant component of the generalized displacement response was proposed and compared to the traditional white-noise-assumed the higher accuracy of the new method was demonstrated. Meanwhile, the effects of the irregularity of the building shapes and the participation of the higher modes on kinds of the wind induced responses at different locations of the structure were analyzed. 3. Based on the relationship between the equivalent responses and the actual results of the structure in different locations under the single-objective equivalent static wind load, the three-dimensional multi-objective equivalent static wind load, which could ensure the response on multiple degrees of freedom of the target floor equivalent, was proposed. Furthermore, both the Non-Gaussian feature of the peak factor and the reduction effect of the multi-objective equivalent were taken into account, which made the corresponding results of the equivalent static wind load more reasonable and reliable.4. Based on the traditional wind-induced response analysis of the long-span roof structure, the frequency-domain method was optimized on the basis of POD (proper orthogonal decomposition) principle and the Two-step Method, which meant firstly modes selection then effective wind-induced response calculation, was presented. The example showed that the scheme proposed not only had the characteristics of simple to extract information, high precision and fast convergence, but also was beneficial to the understanding of the wind load excitation acting on large span roof structures response in principle.5. The expressions of existing equivalent static wind loads for roof structures are related to the correlation between different nodes, which leads to very unevenly distributed. Accordingly, the equivalent static wind load for multi-targets was put forward. In this approach, the sign combination problem of the pulse extreme response for the multi-targets was effectively resolved. Meanwhile, the force distribution of the equivalent static wind load was no longer controlled by neither some single node nor local position, but tended to be more uniform and reasonable. It was also proved that the proposed equivalent wind loads for multi-targets can not only ensure that the responses in key parts are highly consistent with the actual results, but also keep other results in non-critical parts accurate and continuous to some extent.