木构件螺钉结合持久性能研究

采用握钉力试验方法对钉结合蠕变性能进行了研究。结果表明:钉结合强度取决于木材与螺钉的咬合程度和摩擦力;Burger模型可较精确地模拟松木握钉的短期蠕变性能;湿环境下握钉蠕变量显著大于干环境,温度及相对湿度都是影响蠕变的重要因素;应力水平越高握钉蠕变量越大;高湿环境及高应力水平下的握钉蠕变速率最大,在较短时间内便出现握钉破坏;为安全考虑,建议长期使用中应使螺钉握钉力控制在极限握钉力的40%以内。

Study on enduring performance of screw connection in wood structure members

Screw connection′s creep performance has been studied through the experimental method of screw holding power.The results show that the intensity of screw connection lies in the occlusion level and the force of friction between wood and screw.Burger mode can precisely simulate Pinus Stp.short-term creep performance.In the wet condition,the amount of creep is apparently larger than that in dry condition.Temperature and relative humidity are two important factors that influence creep.The higher stress level is,the larger amount of screw holding creep.Creep rate is the highest in the wet condition and high stress level.Therefore,screw connection becomes invalid in short time.Under the consideration of safety,screw holding power should be controlled within 40% of the maximum stress level in the long term.