Experimental investigation and design recommendations for bearing performance of low yield point steel bolted connection

Abstract

To explore the bearing performance of low yield point steel (LYP) bolted connections and quantify their bearing resistance, a total of forty-eight bolted connection specimens with LYP100 and LYP160 core plates were tested subjected to monotonic tensile loads. The influences of the bolt end distance, edge distance, spacing and the bolt pretension on the mechanical characteristics, failure mode and bearing performance of LYP bolted connections were discussed. Furthermore, the nonlinear numerical modeling approach was proposed to accurately reproduce the entire test process and capture pivotal characteristics. A large number of numerical parametric analyses were carried out to evaluate the bearing resistance of LYP bolted connections with the change of key configurations, including bolt end distance, edge distance, spacing and bolt pretension. Finally, the calculation results of the bearing resistance were compared with the design methods stipulated by the specifications of different countries, and the recommendations for the bearing resistance were provided for practical design. The analysis results revealed that multiple failure modes of LYP core plates were observed depending on different values of the bolt end distance, edge distance and spacing, including end tear-out failure, bearing failure, net-section failure and mixed failure. The bearing performance was not only affected by these geometric parameters, but also their correlation. The bolt pretension was capable of improving the bearing behavior, however adversely affected the ductility of the bolted connection. In the case of small end distance, the effect of the bolt pretension on improving the bearing performance was significant, while the influence decreased with the increase of the end distance, because of the accelerated plastic development of LYP core plates. The difference between the cases with and without the bolt pretension became smaller as the loading progressed, owing to the loss of the bolt pretension. The modified Može model was proposed to predict the bearing resistance of LYP bolted connections, not only considering the correlation between the end distance and the edge distance, but also supplementing the influence of the bolt spacing and the bolt pretension. In terms of effective experimental and numerical results exhibiting the bearing failure, the design values of the hole-wall bearing strength of LYP100 and LYP160 steels based on Chinese specification were proposed, which provided a simplified approach for the application of LYP bolted connections.