Simplified design methods of large-capacity moment end-plate connections

Abstract

As the moment resistance demand for beam-to-column connections increases in steel frames involving large spans or heavy loads, ordinary extended end-plate connections may not satisfy the resistance requirement, which is limited by the axial tension capacity of the bolts. Consequently, additional bolts are necessary in moment end-plate connections to meet this requirement. In this case, large-capacity connections with more than 4 bolts in tension region are proposed. The mechanical properties of large-capacity end-plate connections are more complex than those of ordinary end-plate connections. Therefore, although the research of ordinary end-plate connections is extensive, it could not be directly applied to the design of large-capacity connections. To address this issue and provide a unified approach with ordinary end-plate connections, a simplified prediction of end-plate thickness and prying force is suggested in this paper. By considering both the yield-line theory and T-stub model together, a simplified design procedure was proposed for large-capacity end-plate connections. And an appropriate regression value for the effective length based on specific equivalent T-stub models is suggested in this paper. Through comparative analysis, it is found that the method proposed in this paper has a better agreement with the experimental and finite element results than the design results of the LRFD and ASD codes. In addition, considering the influence of some detailed configuration such as flush end plate at lower end, extension stiffeners, center bolts at x axis of beam etc., the methods proposed in this study provided sufficiently accurate results and wider applicability. Furthermore, the prediction of end-plate thickness and prying force of the wide ＆ long end plate connection is also proposed in this paper, which has not been mentioned in all the current specifications. In summary, the predictions of end-plate thickness and prying force proposed in this paper is not only simple and easy to calculate, but also has good accuracy and wider applicability. It can provide a key step for the design of large-capacity end-plate connections. It can also provide basic research data for the popularization and application of large-capacity end-plate connections.