粘贴钢板加固木梁持荷1200d受力性能试验研究

试验中设计了2根足尺木梁,包括1根未加固对比木梁和1根粘贴钢板加固木梁,进行了1200 d的长期持荷试验。试验结果表明：加固木梁与对比木梁均有明显的初始蠕变阶段和稳态蠕变阶段,但加固木梁的跨中挠度和跨中曲率增量明显小于对比木梁,说明加固钢板对木材蠕变具有约束作用;木材应变总体上随温度和湿度的升高而增加、随温度和湿度的降低而减小。采用老化理论、Burgers模型和五参数模型对对比木梁的跨中挠度-持荷时间曲线进行了参数拟合和预测,验证了五参数模型可满足初始与稳态蠕变阶段的计算精度,能够较好地进行木梁蠕变的预测。采用ANSYS中的蠕变方程,并基于所提出的蠕变参数分时段线性化的方法对粘贴钢板加固木梁的长期挠度进行了模拟,计算结果具有较好的精度。

Experimental study on mechanical behavior of timber beamstrengthened with steel plate during 1200-day sustained loading

Two full-size timber beams were designed to investigate long-term behavior for 1200 days, including a reference unstrengthened beam and a timber beam strengthened with steel plate. Experimental results indicate that the primary creep stage and stable creep stage are clearly observed both in the reference beam and the strengthened beam, but the increments of the deflection and curvature at the mid-span section of the strengthened beam are smaller than those of the reference beam, which reflects the restraint effect of steel plate on the long-term performance of timber beam. The strain of the wood was observed to increase with the increase of the temperature and moisture content. Aging theory, Burgurs model and the five-parameter model were fitted to predict the mid-span deflection to time curves of the reference beam. Comparison between the prediction and experimental results shows that the five-parameter model has satisfactory accuracy at both the primary stage and the stable creep stage, and could provide fairly accurate prediction. Finally, a numerical model was developed using the creep equation bulit-in ANSYS to simulate the long-term deflection, while the coefficient in the creep equation was defined as constant at each time step and calculated by linearization technique. The predicted results are in good agreement with the test results.