Flexural behavior of timber connection with various multiple-bolt configurations

The goal of this research is to investigate the behavior of timber connection subjected to bending moment. The effects of multiple-bolt configuration on maximum moment resistance, moment-rotation curve, and failure mode of connection are the focus of this study. Four types of bolt configurations are examined for both steel to wood and wood to wood connections.Failure in the main member is expected to be the failure mode of the connections. Wood specimens of shorea obtusa of 1.5-inch thickness and steel plate of 4-mm thickness are used. The maximum moment resistance of connections is predicted by applying the rigid plate assumption. Results from single bolt connection tests have shown that loading angle drastically affects the lateral load resistance and elastic slip modulus of bolted connections. Lateral load resistance and elastic slip modulus decrease as the loading angle increases. Hankinson formula can be applied to find the lateral load resistance and elastic slip modulus in inclined angles to wood grain. In multiple-bolt connections, all steel to wood connections yield less moment capacity than theoretical prediction; the highest ratio between experimental and theoretical maximum moment resistance is 0.77. In wood to wood connections, the ratio between experimental and theoretical maximum moment resistance varies from 0.80 to 1.23. Wooden plates as side members in wood to wood connection allow more load redistribution among bolts. Therefore, wood to wood connection shows more capacity than steel to wood connection significantly. Bolt configuration affects the steel to wood and wood to wood connections in similar manner. Bolt configuration which has long distance along the grain between bolts yields high moment capacity, high ductility, high stiffness, and high joint rotation. Wood to wood connection has higher join rotation than steel to wood connection because wood to wood connection behaves with lower degree of restraints. Predicted moment-rotation curves have good agreement with experimental results only in elastic range. In plastic range, predicted moment-rotation curves show some discrepancies because of the rigid plate assumption and uncertain behavior such as wood splitting.