Nonlinear interaction effect on main cable clamp bolts tightening in suspension bridge

Abstract Elastic interaction effect commonly exists in the assembly of multi-bolted joint. It is defined as the loss of tension forces in some bolts due to progressively tightening of neighboring bolts. Main cable clamp is a large size bolted joint used in suspension bridge. Investigation on the interaction effect of the clamp bolt tightening has seldom been reported. This article presents a field experiment to study the interaction effect on the clamp bolt tightening. In the experiment, three types of clamp and three tightening sequences were included. Then, finite element models considering the actual nonlinear transverse compressed behaviour of main cables were devised to simulate the bolt tightening procedures, thus providing an effective numerical tool to understand the nonlinear interaction effect on clamp bolts tightening. The experimental results provide validations for subsequent numerical studies, showing that the devised finite element modeling method can effectively predict nonlinear deformation of the main cable and the residual tension force of the clamp bolts. Moreover, the tightening efficiency of different tightening sequeces are discussed based on the experimental and the numerical results. Conclusions can be drawn that for the clamps with much longer length and much more rows of bolts, the degree of the nonlinear interaction effect tends to be higher. The side-to-centre bolt tightening sequence is more effective than the centre-to-side sequence.