Stability Of Main Frames Of Steel Arc Gates

Radial steel gates'main frame is the steel frame under special boundary conditions. The research on the stability of the steel frame is a main subject involved in the research on steel's structure, especially the study of the stability of the steel frame under practical running conditions. The stability of steel arc gates'main frame is based on the method of calculating effective length coefficient. The recommended numerical range of the calculating effective length of the steel arc gates'main frame has been given by the current SL74-95 Specification for design of steel gate in hydraulic and hydroelectric engieering. And in the illustration of Norm, the accurate analytic formula based on the analysis of the elastic buckling of the steel arc gates'main frame has been pointed out, but the formula is transcendental equation, which is not convenient to be solved and whose recommended date range is a little large and is difficult to determine in the design.According to the displacement method, this paper put forward the method of directly calculating effective length coefficient of steel frame and steel arc gates'main frame, and improved that calculating formula with the consideration of asymmetric load, column end bending moment and shearing force and posed the stability equation of lateral frame and longitudianal frame of radial steel gate according to the elastic stability theory as well as the secondary analysis method of calculating stability longitudinal frame of radial steel gate by the structural secondary analysis theory. The main research work and achievements involved in this paper are as follows:1. By analyzing the elastic stability of plane steel frame with the displacement analysis method, the elastic stability equation and characteristic equation of radial steel gates'main frame were established.2. According to the characteristic equation of analyzing the stability of plane steel frame, considering the special condition of column binding of steel arc gates'main frame, the calculating effective length coefficient equation of calculating stability of steel arc gates'main frame was got. And the stability balance equation and characteristic equation under arbitrary bracing rigidity and column binding conditions were derived and the critical load of trapezoidal frame of steel arc gates'main frame's main crossbeam was easy, accurate, and clear compared with the method recommended by the current Norm.3. On the basis of what is required of the construction of the main frame of the curve radial steel gate by the current SL74-95. Specification for Design of Steel Gate in Hydraulic and HydroelectricEngieering, as well as the regulations made by GB50017-2003 The Design Code of Steel Construction that the buckling model of the main cross beam's portal frame of the curve radial steel gate is the anti-symmetrical buckling of the finite sideway of weak frame support. By using the displacement method, this paper proposes an approximate formula of calculating the effective length for columns of the frames with the consideration of the stiffness support's function. The given formula is better in accuracy and has practical applications.4. According to the structural secondary order analysis theory, the secondary analysis method of calculating stability longitudinal frame of radial steel gate was proposed in the paper.