The load factor in bolted timber joints under external tensile loads

These experiments sought to empirically determine how the initial tightening force influences the ratio of the axial bolt force to the tensile load (load factor) and the load required to separate the joint interface (interface separation load) in tensile bolted joints of glued laminated timber. Load factor decreases with increasing initial tightening force; however, this tendency is reduced the greater the washer-member-end distance. In addition, tensile stiffness increases with decreasing load factor, and the interface separation load increases with increasing initial tightening force. However, in actual testing, the joint interface separated at a lower load that predicted mathematically based on the load factor and initial tightening force.