Mechanical Properties of Disconnectable Coupling Joints for Steel Bracing under Eccentric Load

Abstract

Disconnectable coupling (DC) joints of steel bracing in foundation pit engineering are inevitably subjected to eccentric load, but their mechanical properties under eccentric load have not been thoroughly investigated. Based on full-scale test results of DC joints under axial compression, a validated finite element model was established. The bearing capacity and flexural performance of DC joints under eccentric load were studied systematically through a series of numerical simulations. These parameters included the length, width and height of the steel wedge; eccentricity; steel tube wall thickness; channel steel thickness and middle-rib plate height. Based on the numerical results, a modified moment–rotation model was established. The results obtained show that the numerical models accurately reflect the failure mode and the load-displacement curves revealed by the full-scale test. The bearing capacity and flexural performance of DC joints decreases with eccentricity, middle-rib plate height, and steel wedge height. The effect of eccentricity is the most significant. By contrast, the bearing capacity and flexural performance of DC joints increases with steel wedge length, steel wedge width, channel steel thickness and steel tube wall thickness. The modified moment–rotation model can describe the flexural performance of DC joints accurately under eccentric load.

Study on the Influence of the Performance Weakening of the Disconnectable Coupling (DC) Joint of Steel Support on the Retaining Structure of a Foundation Pit

“…The steel wedge is prone to loosening due to its structural design, leading to the dissipation of the pre-axial force [10]. As a result, the full potential of the steel supports is not realized [11], and the DC joint becomes a critical vulnerability in the steel support system, compromising the overall bearing capacity. The inadequate performance of these joints can lead to catastrophic failures, as evidenced by several foundation pit accidents [12][13][14].…”