Research And Application Of Wind-resistant Design Theories Of Large-span Roof Structures Based On Wind Pressure Spectra

Large-span roof structures has been widely employed in large infrastructures,cultural and sports venues in recent years.As the development of wind resistant design theory always lags behind engineering practices,the wind resistant design is still the key but difficulty in designing and constructing such buildings.Especially when flows approach such buildings,complicated aerodynamic would occur,making it harder to express the complex time and frequency domain characteristics of wind loads.Moreover,such structures usually behave spatically,presenting more densely distributed vibration frequencies.Thus,the high-order modal contribution and modal coupling effects are significant,undoubtedly add the difficulty in the estimation of wind-induced responses and the equivalent static wind loads.In the research and engineering practices,researchers and engineering designers from home and abroad have accumulated huge amount of data and methodologies on typical large-span roof structures.Due to the lack of systematic summarisation,comparison and analyses,these data and methodologies seem too complicated in expressions to be grasped by engineering designers and to offer direct and effective suggestion for engineering practices.The present thesis comprehensively studied and compared time and frequency domain methodologies in wind-resistant design theories and their applicabilities,conclusively deeming that frequency domain methodologies is more beneficial and potential in forming the codification system and applicatio n in database-assisteddesign.Based on a large amount of wind tunnel results on typical large-span roofs,the wind pressure fields on different roofs were quantitatively investigated.The influence of body-induced turbulence on spectral parameters has been discussed.And the nexus between the spectral parameters and wind-induced responses,equivalent static wind loads were established.Thus,a set of wind resistant design theory on the main large-span roof structure was proposed.The main content of this work can summarized as follows:(1)Based on the spectral analyses of 1730 cases,18048 samples of wind pressure data measured in the wind tunnel on 5 typical(flat,cantelevered,cylindrical,spherical and saddle)large-span roofs,a uniformed engineering spectral model for wind pressure fields was summarized.The spectral parameters can quantitatively describe the characteristics of wind pressure fields under body-induced turbulence,which possess both relatively clear physical meaning and stable digital ranges,laying the foundation of future analyses and applications.(2)Based on the filter approach for the natural exciations,the engineering spectral model of wind pressure was applied in the wind-induced response analyses,the relationship between the spectral parameters and the wind-induced responses was established,thus an algorithm of high efficiency and accuracy was proposed to estimate the wind-induced responses on large-span roof structures.The modal combination was simplified and the corresponding criteria were discussed to enhance the computational efficiency without sacrifice too much accuracy.(3)Based on the concept of equivalent static wind load,the connotations background and resonant effects were discussed in a frequency domain perspective.A completely correlated quasi-static basic equivalent static state was deducted mathematically.The relationship between spectral parameters and the background,resonant coefficients were built,establishing a gust response envelope approach for the equivalent static wind load for large-span roofs.(4)23940 cases of parametric wind-induced response analyses were carried out on the different large-span grid structures.The impacts of roof geometries,approaching flow conditions and structural parameters on the background and resonant coefficients were discussed.The recommendations for the equivalent static wind load on typical large-span roofs has been proposed based on statistical analyses.(5)Based on the above studies,considering the different roles of engineering designers and wind researchers played in the wind resistant design procedures,corresponding function modules were developed,which were finally integrated in a Wind Resistant Design Software(WRDS)for large-span roof structures.The wind pressure spectral modelling was regarded as a data preprocessing and compression technique.And the wind pressure spectral parameters served as important basic inputs for the data training and prediction,wind-induced response analyses,equivalent static wind load estimation,stochastic simulation and so on.The software was believed to provide a basis of intelligent wind resistant design for large-span roofs in the big data age.