| The lightweight steel portal frame structure has been extensively used in the industry and civil buildings in recent years, because of the rational force bearing, large numbers of tapered members appear in this kind of structure. Many scholars have made researchs about the tapered beams, some equations have been listed for tapered beams by domestic codes and regulations, but problems exsist, for example, bad calculation accuracy,conservative calculation result,economics deficiency, and should be made further research.The article includes three parts, the first part compared and analysed the equations of tapered beam stability in<Technical specification for steed structure of light-weight Buildings with gabled frames>(CECS 102:2002),<Stability of Steel Structures Theory and Design> and EC3 (Eurocode 3:Design of steel structures), and made supplementation about the taperesd beams which is not mentioned in EC3 for analysing and acculating elasto-plastic flexural-torsional buckling critical load of tapered beam.The second part established the finite element model of tapered beam in the range of large-deflection and elastoplasticity by applying the theory of nonlinear finite element and ANSYS. The results of bearing capacity,buckling mode and stress distribution.The third part got the finite element results of stability bearing force by changing the flange width-thickness ratio,ratios of height to thickness of web and web tapering ratio, discussed effect of geometric parameter for the elastoplastic stability bearing capacity of tapered beams, and fited the reduction coefficient by SPSS16.0 At last compared the results of finite element calculation with the results of modified EC3 and other two equations.From the analysis above, the modified equation has higher calculation accuracy than the other two equations, is economic and the error is within the applicable range,so it can be an important reference for the calculation of tapered beams. |
PDF Full Text Request