Repetitive behavior of an advanced demountable bolted shear connection in push-off tests

Currently, the repetitive behavior of the advanced bolted shear connector embedded in non-shrink self -com-pacting high strength pouring material (HPG) is unclear, restricting its application in steel-concrete composite beams (SCCBs). This study examined the repetitive performance of 21 push-off test specimens using different bolt diameters, bolt loads, loading paths, and loading programs. The failure models, load-slip response, shear bearing resistance, initial slip load, shear stiffness, peak slip, and ductility of this advanced bolted shear connection were evaluated. Bolt shearing off is the typical failure mode for all specimens, along with some concrete crushing underneath the bolts. Under repetitive loading, bolt shear capacity and load-slip response are similar to those under monotonous loading. Peak slip grows with the increase of bolt diameter under repetitive loading compared to monotonic loading. The shear stiffness under repetitive loading is lower than that under monotonic loading and improves with the bolt diameter and the bolt pretension increase. The ductility ratio under repetitive loading is smaller than that under monotonic loading and enlarges with the increase of the bolt diameter. Some design recommendations are proposed based on the existing formulae for predicting this advanced bolted shear connection.

Automated summary

This study investigated the repetitive performance of an advanced bolted shear connection used in steel-concrete composite beams. Various parameters were considered, including bolt diameter, bolt load, loading path, and loading program. The failure mode, load-slip response, shear bearing resistance, initial slip load, shear stiffness, peak slip, and ductility were evaluated. It was found that bolt shear capacity and load-slip response were similar under repetitive loading as compared to monotonous loading. Additionally, it was observed that peak slip increased with the increase in bolt diameter under repetitive loading. Design recommendations based on existing formulae were also proposed.