Experimental and numerical study on cable breakage equivalent force in cable-stayed structures consisting of low-relaxation seven-wire steel strands

Abstract

Investigation of a global structural dynamics model of a cable-stayed structure subjected to the cable breakage event requires the determination of the Cable Breakage Equivalent Force with respect to time [CBEF(t)]. The CBEF(t) is an applied axial force to the structure from the stay cable considered to break which is reduced from before the breakage to after the breakage. In this study, a generic CBEF(t) in cable-stayed structures consisting of low-relaxation seven-wire steel strands is obtained experimentally and numerically. The generic CBEF(t) can be introduced in a global structural dynamics model of a cable-stayed structure directly, without the need of a very detailed and costly model for the cable breakage. An experimental program was performed as representative of a stay cable, for which three different lengths of the 3/8-inch strand were tested. A full 3D finite element (FE) model was also developed in ABAQUS/Explicit in which, by a predefined imperfection, the breakage location corresponding to the experimental observation was assigned to the FE models of the 3/8-inch and 0.6-inch strands. The results reveal that the CBEF(t) is determined in two time intervals: a tensile rectangular force in the first and a compressive force in the second. Moreover, the breakage location affects the CBEF(t), while the CBEF(t) is independent of the total length of the unbroken strand, lubricating, and the interaction between the broken cable and the damaged cable-stayed structure. The comparison between wires shows that the main part of the CBEF(t) is related to a center wire. In the last part of this paper, a simplified and generic CBEF(t) is proposed which can be used for global dynamics models of all cable-stayed structures with 3/8-inch and 0.6-inch strands.