拉压区复合加固木梁抗弯性能试验研究

为了有效提升古建木梁的承载能力，提出采用拉区粘贴纤维复合材料、压区内嵌钢筋的复合加固方法。对11根矩形木梁进行三分点加载试验，主要考虑加固方法、受拉区名义配筋率和木材种类等影响因素，观察并记录试件的受力过程及破坏形态，获取试件的荷载 挠度曲线及荷载 应变曲线，进而分析各因素对木梁抗弯性能的影响。研究结果表明：仅拉区加固时，木梁试件的承载力、刚度和延性随着受拉区名义配筋率的增加而提高，但提升幅度不显著；拉压区复合加固木梁的承载力及刚度均高于仅拉区加固木梁，采用拉压区复合加固能显著提高原木梁的承载力及刚度，但其延性略有降低；在相同加固方法下，加固松木木梁的承载力及刚度提高幅度要优于杉木木梁。加载过程中，木梁跨中截面应变沿高度方向基本符合平截面假定，木材与加固材料的应变基本一致，表明拉压区复合加固方法可以保证木材与加固材料间的协调工作。基于试验结果，提出拉压区复合加固木梁的承载力计算模型，其理论计算值与试验结果吻合良好。

Experimental study on flexural behavior of timber beams strengthened in #br#both tension and compression zone

In order to effectively improve the bearing capacity of ancient timber beams, a composite strengthening method of bonding fiber reinforced polymer in the tension zone and embedding steel bars in the compression zone was proposed. 11 rectangular timber beams were designed and tested, in which different strengthening methods, nominal reinforcement ratio in tension zone and different timber types were considered. The whole mechanical process and failure modes of all specimens were observed and recorded, the load-deflection and load-strain curves were obtained. The influence of various factors on the flexural behavior of the timber beams was analyzed. The test results indicate that the bearing capacity, stiffness and ductility of the strengthened timber beams only in the tension area are all improved with the increase of tension nominal reinforcement ratio, but the increase range is not significant. The bearing capacity and stiffness of timber beams strengthened with tension and compression zone are higher than those of the strengthened beams only in the tension area. The bearing capacity and stiffness of log beams can be significantly improved by composite strengthening in tension and compression zone, but the ductility is slightly reduced. Under the same condition, the bearing capacity and stiffness of the strengthened pine beams are better than those of the strengthened fir beams. During the loading process, the strain profiles of mid-span cross-section were nearly linear, and the strain of the wood and the strengthening material was basically same, indicating that the composite strengthening method can ensure the coordination between the wood and the strengthening material. The experimental results agree well with the theoretical values, which prove the correctness of the proposed model for the bearing capacity of timber beams strengthened in tension and compression zone.