Strength of Bearing-type Multi-row Bolted Connections of FRP Composite Members with Varying Cover Plate Stiffness

This paper is to examine the ultimate strength of bearing-type multi-row bolted connections of fiber reinforced polymer (FRP) composite structures with varying cover plate stiffness. Connections of a double-lap configuration with one to four rows of bolts subjected to tensile loads have been studied to understand the effects of cover plate stiffness on ultimate strength as well as failure mode of the connections. A three dimensional progressive damage model of FRP composite material is developed and implemented in a commercial finite element analysis software, with failure criteria and degradation rules of material properties to simulate the connection failure. Failure modes and ultimate strengths of the connections predicted by the numerical analysis are in good agreement with experimental results. The results show that the cover plate stiffness affects the ultimate strength of connections, and that the ultimate strength of a connection with FRP cover plates is larger than that with steel cover plates, which implies that cover plate stiffness should be taken into consideration when a bearing-type multi-row bolted connection is designed.