| Steel structure transmission tower is an important support structure in large transmission lines,and its structural strength and stiffness design is an important work,and the design code of structural strength and stiffness of the main loads that various steel transmission towers will experience during service has been formed.However,in view of the harm of the transmission tower in some special geological zones,as well as the influence of the atmospheric environment in the long service period,its steel structure will always have different degrees of corrosion phenomenon,so that its structural strength and stiffness erosion and other problems are not very sufficient.Therefore,the work of this thesis takes the typical steel and tower type of steel structure transmission tower as the research object,and carries on the corresponding experiment and the theory research for the influence of steel corrosion damage quantity corresponding to different length of time on the impact performance of the transmission tower structure against falling rock,It has certain scientific and practical significance to develop the basic theory of the design of steel structure transmission tower and to improve the operation and control of the transmission tower in service.In this thesis,firstly,according to the problem of corrosion damage of steel corresponding to different length of time,based on the rainfall data of a certain area in southwest China,the peak monthly rainfall situation and the cumulative continuous rainfall time in a region of southwest China are statistically collated.Through the modeling analysis and comparison analysis of the annual rainfall duration single probability density function in this area by five typical probability distribution functions,the mixed probability density model is determined and established by using the linear combination based on the Gumbel distribution,and the corrosion time sample points encountered by the high voltage transmission tower during the service period are established.The corrosion weightlessness of tower steel members without any anti-corrosion protection measures during the service period is estimated,as well as the working conditions and specimens of accelerated corrosion test.Secondly,in view of the rockfall impact resistance of steel structure of transmission tower,the power transmission tower scale model is established by using the dynamic similarity relationship.Through the dynamic response test of the transmission tower structure under the impact load of falling stone,the dynamic response analysis of the transmission tower structure under different impact energy is carried out.The time-history curves of acceleration and strain of impact rigion and different structural heights with the impact mass,impact angle and release height are studied.Finally,according to the influence of the corrosion damage of steel corresponding to different length of time on the impact resistance of the transmission tower structure against falling rock,the variation law of the dynamic characteristics of the structure with the degree of corrosion is analyzed and discussed based on the variation law of the yield strength and elongation of the material under different corrosion damage degree.The dynamic response results of corrosion damage to the structure of transmission tower under impact load are verified by impact test.Through the research of this thesis,the main conclusions are as follows: the mixed probability density model established based on the linear combination of gumbel distribution is in good agreement with the measured data,and the corrosion weight loss rates of 10%,20% and 30% determined by combining with relevant research are representative to some extent;When the small steel ball simulating rockfall hits the second frame leg of the tower body at a height of 0.5m and a slope of 40 degrees,the steel ball mass at 50 g,100g and 150 g are all linear elastic responses,and plastic deformation occurs at 200 g.For the same 200 g steel ball impact at the same condition 10%,20%,30% of the corrosion loss rate and compared with the non-corrosion loss rate,the transmission tower impact resistance decreased significantly.In this thesis,the model of rainfall mixed probability density is established,the scale model of transmission tower and the simulation experiment method of falling rock impact,as well as the research results of different corrosion weightlessness rate on the impact performance of transmission tower anti-falling stone,which can be used for reference and reference in relevant research. |
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