张弦及加载方式对预应力胶合木梁受弯性能的影响

Effect of Jacking and Loading Methods on the Bending Performance of Prestressed Glue-lumber Beams

采用一点张弦一点加载、一点张弦两点加载、两点张弦一点加载、两点张弦两点加载等4种不同的张弦加载方式,对4组12根预应力胶合木梁进行受弯试验,分析4种不同张弦和加载方式对预应力胶合木梁受弯性能的影响。结果表明:在预加力数值一定的前提下,加载点相同时,改变张弦方式对胶合木梁的极限承载力影响不大;张弦点相同时,两点加载比一点加载胶合木梁的极限承载力提高28.8%~38.9%;只有两点张弦两点加载时,梁顶受压区出现褶皱、梁底发生延性受拉破坏,其余破坏形态均为梁底脆性受拉破坏;加载过程中,两点加载较一点加载梁刚度略有提高、可使木材的抗压强度发挥更为充分,提高木材与钢丝的利用率。

Using one point jacking and one point loading,one point jacking and two points loading,two points jacking and onepoint loading,two points jacking and two points loading with four different jacking and loading methods in bend test of fourgroups twelve prestressed gluelumber beams,we measured the effects of the four different jacking and loading methods onthe bending performance of prestressed gluelumber beams. In the same preenergizer preconditions with the same loadingpoint,changing the way of jacking has little effect on ultimate bearing capacity of gluelumber beams. The same jackingpoint,two loading points than one loading point the gluelumber beams ultimate bearing capacity increased by about 28.8%-38.9%. Only when two points jacking and two points loading the top of the beam compression zone wrinkles and beambottom occurs ductility tensile failure,the remaining failure modes are brittle beam bottom tensile failure. In the loadingprocess,the two points loading than one point loading beam stiffness increased slightly,it also can make the timber compressive strength play more fully and improve the utilization rate of wood and steel wire.