Experimental assessment of horizontally mechanically laminated wood beams

The objective of this research was to test horizontally mechanically laminated wood members for potential use in agricultural buildings and various commercial and industrial applications including bridges. Mechanically laminated beams can be built by mechanically fastening dimension lumber together to form a composite beam which is of adequate size to allow its use in timber bridge systems. Mechanically laminated beams also can be constructed using shear transfer plates (STPs) alone or in combination with bolts.; Preliminary testing has involved determining the load-displacement characteristics of the shear plates and bolts. Four trial beams have been tested. Beam one consisted of two pieces of dimension lumber joined by one-half inch diameter bolts and 4 x 5 inch STPs. Beams two and three were similar to beam one except that they had three and four laminations, respectively. Beam four was made up of six laminations and was similarly joined by bolts and STPs. All beams were tested with a single concentrated load at the mid-span.; These initial tests were performed to aid in the development of an analytical model which can predict the stiffness of the composite beams. The model uses a mesh of finite elements to model the lumber and special connections to model the STPs and bolts. The mid-span deflections predicted by the finite element model were compared with experimental mid-span deflections obtained from beam tests, and there was good agreement between the values. Except for the cases of two beams tested in which the model under predicted and over predicted the actual deflection by 25.50%, all other predictions had errors in the range of +5.27% to {dollar}-{dollar}16.31%. Bolt and plate tests were performed for the purpose of obtaining bolt and plate joint stiffnesses which were needed in the finite-element model. Attempts to develop a strength-of-materials model to predict deflections were not successful. Further investigations are needed in this area. Moisture-content and specific-gravity tests were performed on the lumber.; This study is the first step toward determining the feasibility for using horizontally mechanically laminated wood beams. Major progress has been made toward that goal.