Study on shear behavior of super-tightened high-strength bolted group connections

Shear tests on 63 super-tightened high-strength bolt groups were carried out to investigate the damage mode, load displacement, ductility, and other mechanical indicators. The effects of key parameters such as different core plate thickness, super-tightened bolt number, super-tightened bolt position, and the high-strength bolts preload force on the shear performance of high-strength bolt group were analyzed. The finite element model was built and a parametric expansion investigation was carried out. Results have demonstrated that the failure mode is typical bolt shear damage, with cover end deformation and bolt hole extrusion deformation. The increment of super-tightened bolts number and the super-tightened bolt preload improve the anti-sliding bearing capacity. However, plate thickness and super-tightened bolt position have no effect on the anti-sliding bearing capacity. The shear ultimate bearing capacity of the super-tightened high-strength bolt group is not significantly different from that of the standard specimen. The ductility is negatively correlated with the number of super-tightened bolts and the super-tightened bolt preload, but the decrease percentage is within 25%. Additionally, the results obtained from the finite element simulation are in agreement with the experimental findings. The simulation analysis shows that increasing the strength grade of high-strength bolts would enhance the ultimate bearing capacity. The specimens treated with sprayed quality quartz sand exhibit a higher anti-sliding bearing capacity compared to those with a clean rolled plate surface. Finally, the genetic algorithm was used to obtain the optimal and most unfavorable states under different mechanical properties based on experimental data.