| Transmission tower-line system is an important lifeline project, which plays an important role in Chinese economical construction. In recent decades, the transmission tower-line systems are often destroyed by earthquakes with the increasing of tower height and line span. Transmission tower-line system is a large span continuous structure, and induces to the different excitations of different supports due to wave passage effect, incoherence effect and local site effect. As to transmission tower-line system, multi-component and multi-support seismic excitation is one of the main reasons of seismic damage, and it is significant to analyze the seismic performance under multi-component and multi-support excitations. Presently, there are less studies on seismic response analysis of transmission tower-line systme considering multi-component and multi-support seismic effects. Meanwhile the calculation model considering multi-component and multi-support analysis is not found. The five aspects of work done in this thesis are listed as follows:(1) Multi-component and multi-support ground motion time histories are generated in view of the continuous structure of transmission tower-line system. Based on the design response spectrum defined in the Chinese Code for Design of Seismic of Electrical Installations, the power spectral density of the acceleration at the ground level is evaluated by an iterative approach. Using the nonlinear fitting technique, the model parameters can be obtained to fit the power spectral density function of the Clough-Penzien filtered white noise model and generated power spectral density function. Linear type, fold line type and topographic variation type multi-support ground motion time histories are generated, respectively. Furthermore, the correlations between every two components of multi-component ground motions are derived. Finally, multi-component and multi-support ground motion time histories are generated. In order to verify the accuracy of the theory model, strong motion seismographs are arranged.(2) Transmission tower-line system shaking table model is designed and made, and multi-component and multi-support shaking table experiment is carried out. Non-proportional in shaking table modeling power transmission tower-line system is studied, and the similarity theory is perfected and verified according to numerical calculation method. Based on the practical engineering, the transmission towers model and the transmission lines model are desigened, and the experimental model is made. The multi-component and multi-support shaking table experiment of transmission tower-line system is conducted according to shaking table arry system, and the natural vibration frequency between experimental model and finite model are compared. The experimental results show that wave passage effect, incoherence effect and local site effect have significant influence on the response of the system. From the comparison between experimental results and numerical analysis, the rationality of calculation model is verified, which lays the foundation for the further analysis.(3) Based on the practical engineering in Gaizhou city of Liaoning province, transmission tower-line system finite element model is established. The tower, the isolator and the transmission line are simulated by the beam element, truss element and catenary cable element, respectively. According to comaparing the structural system of three towers and two-span lines additional spring model with the model of three towers and four-span lines model, a resonable computational model is performed. The response of transmission tower-line system is analyzed under multi-component excitations, and earthquake waves are slected according to different site condition type. The results show that the response of transmission tower under longitudinal excitation is the most significant in multi-component excitations. The maximum axial force under longitudinal excitation and the maximum axial force under multi-component excitations are fitted, and the fitting factors are given which can provide a reference for engineering design. The longitudinal and transverse maximum displacement responses of transmission lines can be obtained under longitudinal excitation or transverse excitation, but the vertical maximum displacement reponses need to consider multi-component earthquake effects. The responses of transmission tower-line system under multi-component and multi-support excitations are analyzed. The results show that the response of the system is large when the traveling wave velocity is small, the degree of correlation is low, the differences of site conditions are large. Moreover, the correlations between every two components of multi-component earthquake motions have insignificant effect on the response of the system.(4) Based on the practical engineering in Liaoning province, linear type and fold line type transmission line finite eleemnt models are established, respectively. The dynamic characteristics of linear type and fold line type transmission tower-line system under multi-component and multi-support seismic excitations are compared. The seismic performance of the system caused by the influence of fold line is discussed. Multi-component and multi-support earthquake records in SMART-I array are selected, and the seismic response of multiple fold line angles type transmission tower-line system are analyzed. The results show that the responses of system under multi-component and multi-support seismic excitations are different when the angles are different. The responses of linear type and fold line type transmission tower-line system under multi-component and multi-support seismic excitations show that the two models are influenced significantly by wave passage effect, and the responses are large when the traveling wave velocity is low, and the responses of fold line type by the coherence loss effect and the local site effect are smaller than the responses of linear type structural system.(5) Topographic variation type transmission line system finite element model is established, and the responses of the model under multi-support seismic excitations are analyzed. The transmission towers are assumed to locate in the crest of peak and vally floor respectively. The results show that the traveling wave velocity has a significant effect on the two models, but the degree of the effect is different. Wave passage effect of earthquake ground motion can not be neglected. The larger is the difference between the site conditions, the larger are the responses of the structure. The responses of transmission tower located in the crest of peak are larger than the response of transmission tower located in the vally fllor. The effect of the local site effect should be taken into consideration.
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