Bolted Connections in Wood under Bending/Tension Loading

Abstract

A mathematical model is developed to predict the load‐deformation (P‐Δ) relationship of single‐bolted connections in wood structures subjected to bending/tension loading. The connections under consideration exhibit a nonlinear P‐Δ pattern from the origin. Analyses are made using a plane‐stress, two‐dimensional, orthotropic, linear‐elastic finite‐element model. An incremental‐iterative secant stiffness approach is employed to trace the nonlinear behavior. The principal response investigated is P‐Δ at the free end of the wood member. Computations are performed on a CYBER 205 supercomputer. The validity of the computer model is determined via comparisons to experimentally obtained P‐Δ curves. Two wood species were included in the experimental phase of this study: a softwood (lodgepole pine) and a hardwood (hard maple). Additional variables examined in this study included: lumber width (nominal 2×4 and 2×6), moisture content (MC) (12% and green), and washer size [0.12 in. (3.05 mm) thick, 1.375 in. (34.9 mm) diameter; and 0.08 in. (2.03 mm) thick, 1.245 in. (31.6 mm) diameter]. It was concluded that the simplified model developed in the study reasonably predicted the shape and magnitude of the P‐Δ relationship of the connection under bending/tension loading. The average weighted error throughout the entire range of deflections studied was less than 17% in most of the 16 specimens evaluated.