Static Behavior And Design Method Of Steel Girders With Large Web Openings

Recently, with the development of high-rise steel structures, steel girders with large web openings are more and more popular with engineers because of the economic benefit. However, the behavior of girders with large web openings is lack of investigation. It is only referred just about the geometrical construction in the China Code (JGJ99-98) of Technical Specification for Steel Structure of Tall Buildings, but no guideline can be used for design in China, so the application of steel girders with large web openings is blocked.To promote the application of steel girders with large web openings, experiments and finite element analysis were carried out. Both stress distributions and deflections as well as the failure mode were investigated and the design method is discussed too. The main research work as following are undertaken:Firstly, experiments on two full-scale girders were carried out. Experimental setup and results are described and it showed that due to the web openings, the behavior of girders with large web openings is different from the girders without openings.Secondly, classical beam theory and Vierendeel truss theory are performed as well as the finite element analysis. Through the comparisons, it is found that Vierendeel truss theory can be adopted safely, but in a certain length beside the opening edge, the stress distribution of the unperforated cross sections is more complex than girders without web openings.Then, several geometrical parameters of the opening that influence the stress distribution along the unperforated cross sections are studied by FEM. Some basic rules are found as following: (1) the length of the influencing zone, that the bending stress distributions along unperforated cross sections are not the same as the girders without web openings, is nearly 0.9 time the opening height. The maximum value of the bending stress in the influencing zone is only determined by the opening height.(2) the length of the influencing zone, that the shearing stress distributions along unperforated cross sections are not the same as the girders without web openings, is nearly equal to the total height of the section. The maximum value of the shearing stress in the influencing zone can be calculated by an equation that obtained by linear regression analysis.Finally, based on the research and design code recently, a design method is proposed and an example is carried out to justify the reliability and practicability of the method.