预应力积成材力学性能的有限元分析

Numerical study on mechanical properties of pre-stressed paminated strand lumber

预应力积成材是将胶合板材剖解成片状单元,然后将片材垂直于板面排列,再由预应力钢丝将其贯穿、挤压形成整体的一种新型结构材料。本文应用有限元软件对其力学性能进行了分析研究。从简支单板面内受弯的承载力分析切入,通过改变构件的几何参数得出了单板内力分布、破坏模式以及承载力的变化规律,然后分析了预应力积成材的内力分布和破坏模式,并且通过对预应力大小、预应力钢丝的直径及其纵向间距、预应力钢丝的上下边距等参数的分析确定了极限承载力随影响因素的变化规律。分析结果表明:单板构件的高宽比越大,破坏模式越趋向于失稳破坏,材料强度越不能得以充分发挥;通过预应力钢丝的合理选取与布置及预应力的合理施加,分散的单板结合成一个共同受力和变形的整体,使预应力积成材的承载力远高于失稳破坏时的极限承载力且稍高于等体积原木的承载力。最后提出了合理参数下积成材的分析模型。

Pre-stressed laminated strand lumber( PLSL) is a new kind of structural material which can be gotten by connecting and squeezing the vertically arranged sheet units sawing from plywood by pre-stressed steel wires. The loadcarrying capacity of the simply supported plate under inside compression is analyzed to discuss the varying rules of the internal forces distribution,failure mode and ultimate bearing load with the height-width ratio. In addition,the distribution of internal forces and the failure mode of PLSL are discussed. Then the influences of magnitude of pre-stress,distribution of steel wires,diameter of steel wires,longitudinal spacing of steel wires,as well as edge distance of steel wires on ultimate bearing load are discussed by parametric research. The analysis results show that,the larger of the height-width ratio,the greater tendency of the instable failure,and more percentage of the material strength can not be exploited;Dispersed veneers can be deformed as a whole through reasonable selection and distribution of pre-stressed steel wires. So the ultimate bearing load of PLSL is much higher than the instability bearing load,and slightly higher than the crude wood of same volume. At last,an analysis model under reasonable parameter is put forward.