高强轻骨料混凝土深受弯构件受剪模型分析
SHEAR STRENGTH MODEL FOR HIGH-STRENGTH LIGHTWEIGHT AGGREGATE CONCRETE DEEP FLEXURAL MEMBERS
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摘要: 根据集中荷载作用下8根剪跨比0.26~1.04、跨高比为2和3的LC40级高强轻骨料混凝土简支深受弯构件受剪性能试验结果,重点分析了该类混凝土深受弯构件的破坏过程与破坏形态。在试验研究的基础上,建立了基于软化拉-压杆模型计算理论的高强轻骨料混凝土深受弯构件受剪承载力计算模型,并应用该模型完成了22组该类构件受剪承载力试验计算与我国GB50010-2010、ACI318-08、CSA和EC2等现有规范计算结果及软化拉-压杆模型计算结果的对比分析。分析表明:高强轻骨料混凝土深受弯构件破坏形态分为剪切破坏和弯剪破坏两种,剪跨比λ≤1,其受剪承载力基本由混凝土斜压杆控制,软化拉-压杆模型计算结果接近试验值,与现行规范计算结果相当,但软化拉-压杆模型有明确的力学模型,能够合理反映深受弯构件受力机理。Abstract: According to the test results due to the action of a concentrated load for eight simply supported deep flexural members whose shear span to depth ratios and span-depth ratios are 0.26~1.04 and 2, as well as 3, respectively, and made of LC40 high-strength lightweight aggregate concrete under, the failure process and failure pattern of this kinds of deep flexural members are analyzed emphatically. The shear capacity model is established, based on softened strut-and-tie model for high-strength lightweight concrete deep flexural members. The model is used to calculate the shear strength of these 24 members, the results of which have been compared with the results accepted from the shear formulas suggested by current design codes, GB50010-2010, ACI318-08, CSA and EC2. Results shows that the failure pattern for high-strength lightweight concrete deep flexural members could be divided into shear failure and flexure-shear failure, and its shear capacity is controlled by concrete diagonal strut. The results of softened strut-and-tie model approach to the data from tests, and agree with the results of the current codes. But the softened strut-and-tie model has a definite mechanical model and can reasonably reveal the failure mechanism of deep flexural members.