Impact Analysis About Steel-Bracing On Seismic Performance Of The Steel Frame-Bent Structure In Large-Scale Thermal Power Plants

The brace is one of the most important component to resist lateral force structure in the steel frame-bent structure. The steel brace-frame structures are widely applied in large-scale thermal power plants in our country. But a sound knowledge of collapse mechanism of steel brace under seismic loading is still insufficient, so that the collapse of steel structures under earthquake takes place occasionally because of the brace local damage. And most thermal power plants of our country are located in earthquake zones, both the levels of resistance to lateral force system and the vertical stiffness distribution of the main building framework are irregular. To fully in accordance with the requirement set to anti-seismic design is difficult.In this paper, firstly, a single common horizontal framework which is vertically irregular to the resistance system is analyses by using the elastic and plastic finite element method with the help of finite element analysis, the framewoke from a certain1000MW the steel frame-bent structure of large power plant. According the common use of lateral load models to analyze the steel frame-bent structure in Pushover analysis. And then, by changing the position of the brace and its form, the results of the load-displacement relational curves, the development trend of plastic hinges and so on as the parameters to estimate if the deformation capacity and seismic resistance of the structure can reach corresponding performance goals. By comparing the results of different brace positions and different forms, evaluate the seismic behavior and plastic hinge distribution and the rule of the double lateral-loads resisting system. Secondly, in allusion to cross-section column of the side span in thermal power plant, the change of effective length coefficient for the variable cross-section column is researched by altering the vertical position of steel brace. Analysis the influence of different brace positions on the calculation length coefficients and the brace points of reducing the effective length coefficient of variable cross-section column. At last, this article deduces the buckling equation of variable cross-section column under considering the action of horizontal force of steel brace at the position of variable cross section,and compares the equations with existing buckling equations without considering the action of horizontal force at the position of variable cross-section. At the end of concluding, the article summarized the research achievements, and give some recommendation of the work.