工程木梁的受弯性能试验研究

Experimental study on flexural behavior of engineered wood beams

以江苏速生意杨为原材料加工的工程木材,包括层板胶合木（Glulam）和旋切板胶合木（LVL）等,提出几种新型的构件截面形式,对受弯构件的结构性能影响因素进行了详细分析。研究的主要目的是充分利用我国速生林资源,并将其应用于现代木结构建筑。首先,通过材料的材性试验,探讨了Glulam和LVL的主要物理力学性能;在此基础上,对31个工程木梁模型试件进行了弯曲性能的试验研究,分析了工程木梁的破坏形态和破坏机理,探讨了其极限承载力和抗弯刚度等弯曲性能,并对构件性能进行了对比;最后,分析了影响工程木梁结构性能的各种因素,包括层板组合方式、荷载方向、单板厚度（LVL构件）以及构件尺寸等。结果表明：工程木梁的结构性能远远超出了建筑中常用锯材梁的结构性能,其强度比樟子松锯材构件高出39.0%-90.0%,刚度高出35.0%-45.0%,若将Glulam与LVL进行优化组合,会取得更好的效果;构件横截面平均应变基本上呈线性分布,构件的极限拉应变约为0.006,而其破坏时的压应变最大为0.009左右;层板组合方式及构件尺寸大小对构件的结构性能影响较大。研究表明,工程木在我国建筑结构领域具有很好的发展前景。

The Italian poplar is applied in the manufacture of engineered wood materials, including glued laminated timber （Glulam）, laminated veneer lumber （LVL）, etc. Some novel beam sections were put forward and the influencing factors upon the flexural behaviors of engineered wood beams were studied in detail. The overall objective of this study is to take full advantage of the fast-growing species in China and make it applicable to modern timber structures. Firstly, through a series of material mechanical testing, the main physical and mechanical behavior of Glulam and LVL were presented. Based on this, experimental study on a total of 31 engineered wood beams was developed and the failure modes and failure mechanism were analyzed in this paper. Then the flexural behaviors, which include load carrying capacity and bending stiffness, were investigated and a detailed comparison was made among them. Finally, the influences of lamination combination, load direction, veneer thickness （for LVL members） , and beam sizes upon the flexural behaviors of engineered wood beams were discussed. Experimental results show that structural behaviors of engineered wood beams were much better than those of sawn beams made from ordinary structural timber. For example, the ultimate load of poplar engineered wood beams exceeds that of sawn Mongolian Scotch pine （MSP） beams by 39. 0% -90. 0%, while bending stiffness increased by 35.0% -45.0%. The combination of LVL with glulam in the beams would produce better structural performance. Also the average strain of beam cross-section show a linear distribution, and the ultimate tensile strain of the beams is 0. 006 while the maximum compressive strain of the beams is about 0. 009. Moreover, the influences of lamination combination and beam sizes on the beam＇s flexural behavior are obvious. The study shows that engineered wood materials have a good prospect in building structures of China.