Load-carrying Capacity Of Pre-stressed Laminated Strand Lumber

Traditional composite timber products such as plywood and glued laminated wood adopt the principle of integration with veneer. They are used in furniture and building decoration, and then gradually applied to the concrete formwork and container flooring. However, as the concrete formwork and the container floor mainly bear large moments, there are some insurmountable shortcomings such as weak bending resistance and poor wear intensity. Then, the pre-stressed laminated strand lumber (PLSL) is proposed. The specific approach is sawing the plywood into sheet units, and then arranges the sheets vertically to form the laminated strand lumber. Secondly, pre-stressed steel wires will become useful in connecting and squeezing the laminated strand lumber into a whole, which is pre-stressed laminated strand lumber. The multiple integration method and pre-stressed technology are adopted to obtain a higher strength. More significantly, used wood can be reused as the raw material of PLSL, and the crude wood will be conserved and the cost may be lowered. Therefore, by determining the influence of major parameters to study the mechanical properties of PLSL will be provided with an important role both in the theoretical and engineering fields.Nonlinear buckling analysis by finite element software ANSYS and static experimental research are both applied in this paper to study the load bearing capacity and the deformation capacity of PLSL. A lot of work has been done to find out the major parameters which gives the biggest effect. Finally some recommendations will be concluded in order to guide the engineering design.Firstly, the analysis of load bearing capacity of the simply supported plate under inside compression is discussed. The distribution of internal forces, failure mode and load bearing capacity have been concluded by changing the geometry of the model. The larger of the height-width ratio, the greater the tendency to instability failure, and more strength of the material can not be fully exploited.Secondly, the variations of ultimate bearing load is determined through a series of parametric analysis, and then the mechanical properties of PLSL is discussed deeply. The parameters include the magnitude of pre-stress, the diameter and the arrangement of steel wires, the shape and the size of the initial defect, the size of the laminated strand lumber as well as the load patterns. Thirdly, the superimposed experiment of wood veneers and the parametric experiment of PLSL are conducted to determine the result of superimposition and the load-carrying capacity, the force mode, the deformation shape, the failure mode of PLSL. The parameters include the magnitude of pre-stress, the diameter and the arrangement of steel wires.Finally, based on the combinated result of FEA and experimental research, a series of pre-stressing recommendations has been concluded in order to guide the engineering design.