FATIGUE STRENGTH OF FRICTION TYPE HIGH STRENGTH BOLTED JOINTS WITH COMPACT BOLT SPACING AND EDGE DISTANCE

Abstract

 Damaged steel bridge members are often repaired by patching steel plates with high strength bolts. Sometimes, due to spatial restriction, there is a need to be shorten bolt spacing or edge distance than those specified in a design specification. However, knowledge on fatigue performance of the joints with the compact bolt arrangement is little.

 In this study, fatigue strength of friction type bolted joints with compact bolt arrangement was investigated through fatigue tests and finite element analyses. The test result indicated that the compact bolt arrangement, especially a smaller end distance, decrease the fatigue strength of the joints. The analysis results demonstrated that stress concentration occured at the surface around a bolt hole where the fatigue crack initiated in the test. Since the stress concentration was strongly correlated to the fatigue strength in the test, the effects of compact bolt arrangement with a variety of material strengths and joint dimensions were discussed based on the stress concentration.