Nonlinear superposition model for the behavior of bolted joints

Summary A previously developed model to predict the load-slip relationship for mechanical joints using one bolt subjected to lateral loading (Part 1) was extended to incorporate the rotational resistance of joints containing two bolts. The rotation is about the long axis direction of the bolts, and considers the wood members oriented at arbitrary angles to the grain. The model utilizes nonlinear translational springs to represent the parallel and perpendicular to grain components of the reaction force present on each bolt resisting the applied moment. A series of experiments were conducted to determine the spring constants of bolted joints in axial loading and to verify the predictions of the mathematical model. Bolted joints subjected to a pure rotation were tested using combinations of steel plates and wood side members experiencing bolt reaction forces at various angles of load to grain. The results indicated an excellent agreement between theoretical predictions and experimentally obtained data.The authors wish to extend thanks to the Colorado State Agricultural Experiment Station for their financial support and to the Fulbright-Hayes Foundation for the educational scholarship and research funding provided to the project