Research On The Influence Of Lateral Supporting Conditions On The Overall Stability Carrying Capacity Of Steel Beams

The overall stability of steel beam is the issue that design and construction must be carefully considered. There are various measures to enhance the overall stability carrying capacity of steel beam, one of the most effective measure is to design the lateral bracing. In practical engineering, lateral bracing is designed in equidistant under normal circumstances, of course, it is designed to be the case of unequidistant sometimes.How to calculate the overall stability of steel beam which have lateral bracing, Code for design of steel structures (GB 50017-2003) only provide method for these lateral bracing is designed in equidistant. In order to reflect the constraints between the beam segments, this method use equivalent critical moment coefficien increasing replace the risk segment calculation length decreasing,which is no convenient for designers to understand the true meaning of it quickly.As for steel beam which lateral bracing is designed in unequidistant, Code for design of steel structures (GB 50017-2003) have no provide calculation method. Therefore, study the overall stability carrying capacity of these beams has important theoretical and practical value.In the beginning, this paper introduces the essence of the overall stability of steel beams, after that the paper introduces the type of the overall stability of steel beams and the method to calculate the overall stability of steel beams in traditional theory .As for doubly symmetric I-section of simply supported steel beams which have no lateral bracing, the paper derive the critical moment of the overall stability under pure bending moment and lateral loads by the energy method. As for doubly symmetric I-section of simply supported steel beams which have lateral bracing under different loads, including the full cross uniformly distributed load, supporting place concentrated load, midspan concentrated load, Etc end bending moment, consider the lateral boundary conditions, beam height, beam width changes, use the method proposed by Professor Chen Shaofan in the ?Guide to Stability Design of Steel Structures? (The Second Edition) and the method provided by Code for design of steel structures (GB 50017-2003) to obtain the overall stability critical load theoretical solutions. but also use ANSYS finite element software as a basic analysis tool,build a finite element model, carry out eigenvalue buckling analysis under conditions of ideal elastic to obtain the overall stability critical load finite element solution.After theoretical calculation and finite element analysis,in some form of loads,first, three kinds of overall stability critical loads are compared to examine the influence of lateral boundary conditions on overall stability carrying capacity of steel beams in this form of loads, second, two kinds of overall stability critical loads theoretical solutions and the overall stability critical loads finite element solutions are compared to evaluate the accuracy and applicability of the two theoretical methods,Final fitting the effectiveness of the coefficient of lateral bracing.