Improved design of extended end-plate connection allowing for prying effects

• The deficiencies of design methods in different standards are discussed.
• New design equations considering prying action are revised.
• Convenient design procedure is proposed.
• Satisfactory accuracy is verified against finite element method.

Connections are vital in affecting the safety of steel structures and connection failure is one of the main causes of structural collapse. Bolt connections are a dominant means of connecting structural members. In the design of bolt connections in steel structures, the effects of prying action on the connected parts and bolts should be considered because use of thick base plates to avoid its consideration results in lack of connection ductility which is undesirable. Although equations are available for prying action in Chinese, AISC and HK manuals or codes, they suffer some deficiencies. To develop a better design method for extended end-plate bolt connection, design formulae in several codes are discussed and compared in this paper. The paper further proposes revision for the current formulae in codes and suggests design formulae for bending moment in bolts and in end-plate. The equations are validated with rigorous finite element results, which show that the proposed method has a satisfactory accuracy for calculation of prying force and bending moment. Further, the suggested equations have the advantages over current methods in the provision of a systematic design for end-plate connection. More importantly, the derived formulae also lay a foundation for the further study of moment–rotation relationship in end-plate connections used in direct or advanced analysis of steel frames.