Investigation of bearing failure in steel single bolt lap connections

• An experimental investigation on single bolt lap steel connections was conducted.
• Experimental results were obtained by an optical 3D measuring system.
• Numerical models were calibrated on the basis of experimental results.
• Parametric study of connections was performed on the basis of calibrated models.
• Equation proposals as an improvement of current provisions were given.

Bolted connections are more than ever used because of their ease of fabrication and erection but often can be a weak link in a structure. Among single bolt lap connection types of failure, bearing mode is generally dominant because of the necessity to ensure bolthole elongation that enables a progressive collapse mechanism. Although ductility represents a positive characteristic, excessive deformations limit the usefulness of a structure or cause the members it connects to fail. Because of the lack of research in representative conditions an investigation of the plastic behavior of single bolt lap connections with a special consideration of bolthole elongation was performed. This investigation consisted of experimental, numerical and analytical analysis. A detailed measurement of deformations during experimental testing was performed with an optical system that enabled the monitoring of strains in 3D. The results of experimental testing were used for the calibration of nonlinear numerical models and a parametric study of connections with different bolthole center to plate edge distances was performed. A larger set of results, derived from the parametric study served as a foundation for the evaluation of empirical expressions given in the European and American standards, and proposal of appropriate equations that enable a better prediction of ultimate and serviceability loads.