GFRP筋混凝土板在拱效应下的挠度计算

针对美国混凝土结构设计规范(ACI440.1-06)未考虑玻璃纤维复合增强塑料筋(GFRP筋)混凝土板中拱效应的作用,挠度往往被高估的问题,对17块端部受到约束的混凝土板带进行跨中集中荷载破坏性试验,以获得更准确的挠度计算方法.结果发现;试件开裂后,拱效应作用逐渐明显.挠度的变化可分为开裂前、开裂时突变和拱效应形成后3个阶段.根据17块混凝土板的试验结果和前人的试验,量化混凝土板中拱效应的影响,结合虚功原理推导出GFRP筋混凝土板的挠度计算方法.板带挠度为净跨的1/800和1/350时,根据ACI规范,按简支板计算的预测荷载为试验值的0.388和0.411倍;所推导方法预测荷载与试验值之比为0.969和1.044.推导方法的预测结果与现行规范计算值进行对比,与试验值吻合得更好.

Deflection estimation of concrete slab reinforced with GFRP bars with consideration of arching action

In the United States Code for design of concrete structures(ACI440.1—06),the deflections of concrete slab reinforced with glass fiber reinforced polymer(GFRP) bars were often overestimated because of un-consideration of arching action.In order to obtain an accurate deflection estimation method,seventeen concrete slab strips restrained at end were tested with concentrated loads at mid-span until being failed.The results show that arching action becomes gradually significant after cracking.Deflection development can be divided into three stages of before cracking,cracking and forming arching action.Based on the test results of seventeen concrete slab strips and literature report,the arching action was quantified to deduce deflection estimation method by virtual work principle.When the deflections are 1/800 and 1/350 of clear span,the load predicted by ACI are 0.388 and 0.411 times of test result,respectively,while those of proposed method are 0.969 and 1.044.Compared with the prediction by ACI,the proposed deflection estimation has better coincidence with test result.