Research On Spectral Model Of Wind Load On Large-span Roofs

Large-span roof structures, characterized as light-weighted and flexible, areextremely sensible to wind load. Due to the diversity of shapes, the wind load acting onthe roofs is predominated by body-induced turbulence. Thus, the quasi-steady theory isnot applicable. The characteristic of wind load under body-induced turbulence has beenviewed as the research focus in structural wind engineering. And the determination ofwind load is one of the key problems to be solved in the wind resistanse design process.Wind load spectra are both important indacators in decipting the fluctuating wind loadsand prerequisites to calculate the wind-induced responses. Because of complicatedaerodynamic and structural dynamic behaviors, the spectral model of wind load isusually sumarrised from wind load measurements through data fitting with specificfomulas. Due to lack of consideration with physical meaning, the fitting results divergelargely, and the parametric sensitivity to structural dynamic response can be merelyestimated. Therefore, it is necessary to improve the modeling theory of wind loadspectra. And a universal, appliable spectral model of wind load is to be proposed.In this dissertation, the modelling process of wind spectral in boundary layer andresearch status of wind load spectral model were reviewed critically. A novel spectralmodel of wind load was proposed, the parameters from which are studied mathmetically,mechanically and physically. Then, spectral model of wind load on typical large spanroofs are built on the basis of the analyses of wind tunnel data. The major researchcontents are listed as follows:1. In analogy to the modelling of wind velocity spectra, mathmeticaltransformation was carried out on a fitting formula of wind load spectra. The wind loadmodel was derived, which was expressed by3auto-spectral parameters and1cross-spectral parameter.2. The influence of4model parameters on structural dynamic responses arestudied based on the random viberation theory. The theoretical research framework ofwind load spectral modeling was built.3. The model parameters were recognized through115cases of wind tunnel data ontypical large-span roofs (flat, cantilevered, cyliderical and spherical roofs). The featureof parametric value range and distribution were studied. The nexus between parametersand body-induced turbulence were discussed.4. Based on the relationship between parameters and body-induced turbulence, thesensitivity of parameters to structural dynamic response, the spectral model of windload on largespan roofs were built from the wind tunnel data. Through the comparisionsof642cases of wind-induce response analyses (including plane trusses, cantileveredtrusses, double-deck cylindrical reticulated shells and single-layer spherical lattice shells) calculated from wind tunnel data and the spectral model, the model and the modelingtheorywas validated. Stochastic simulation, data mining and database technologies wereintroduced to discuss the feasibility of further application of the modelling theory inastimating extreme wind load, analyzing wind load characteristics, predicting wind loadand wind resistanse design in the future.