Mechanical Analysis of High-Strength Bolts Based on Node Fatigue Test

Chongqing Chaotianmen Yangtze Bridge with the main span of 552m is the steel truss continuous tied arch bridge. Track cross beams of the lower layer and nodes of main truss are connected by high-strength bolts. To verify fatigue security performance of this node connection, large-scale model of 1/2 is applied in node fatigue test. In the 2 million fatigue tests during design life, the high-strength bolts at node connection don´t loose. In the next 850 thousand failure tests, the high-strength bolts at node connection loose and fail. Based on the calculation of prying force of connective component, the prying force is 34%-38% of bolt tension. Then by the further calculation of internal force of the high-strength bolt´s connection, the high-strength bolts fail when the external load are 2.5 times of design fatigue load amplitude, which coincides with experimental results. At last, summarize the failure reason and inductive failure law of high-strength bolts of this kind node connection, and provide some reference for the bridge design and bridge monitoring in the future.