作　　者： (刘喜）; (吴涛）; (魏慧）; (张玉）;

机构地区： 长安大学建筑工程学院,陕西西安710061

出　　处： 《工程力学》 2017年第9期211-219,共9页

摘　　要： 尺寸效应对轻骨料混凝土深受弯构件受剪能力影响显著,现有规范和典型抗剪模型均未准确考虑。结合拉压杆模型和裂缝带处能量损失平衡理论,建立了深受弯构件受剪计算模型;在已有大量普通混凝土构件试验研究基础上,量化深受弯构件斜压杆中混凝土项和钢筋项的作用,简化模型,并通过与多国规范建议模型对比分析,验证模型的准确性;进而,考虑轻骨料混凝土与普通混凝土的受剪破损差异,修正模型,结合已完成8根轻骨料混凝土深受弯构件受剪性能试验研究,得到适用于轻骨料混凝土深受弯构件且考虑尺寸效应影响的计算模型。研究表明:基于能量损失平衡建立的深受弯构件的拉压杆模型计算结果较各国规范和Tan-Cheng模型更接近试验值,能够准确预测轻骨料混凝土深受弯构件受剪能力,并合理考虑尺寸效应,具有明确的力学概念。 Previous studies indicated that the size effect has significant influence on the shear capacity of deep flexural members with lightweight aggregate concrete, but it has not been reasonably considered in most existing design codes or typical shear models. This paper proposed a shear model by combining the energy-balance theory in crack band with the strut-and-tie model. Then it was simplified by quantifying the contribution of diagonal strut and shear reinforcement according to a large set of data on normal concrete specimens from the literature. The accuracy of the proposed shear model was observed by comparing it with the computational methods in most existing design codes. Furthermore, this paper modified the proposed model based on the difference in shear fracture mechanics between normal weight and lightweight aggregate concrete. Combined with the eight completed experimental study in this paper, a shear model for lightweight aggregate concrete deep flexural members considering the size effect was presented and verified. It is shown that the predicted results by the new model based on energy-balance theory were in better agreement with the test results than those determined from others current design codes or the Tan-Cheng model. The proposed model with definite shear transmission mechanism and reasonably considered size effect can accurately evaluate the shear capacity of deep flexural members with lightweight aggregate concrete.

关 键 词： 轻骨料混凝土 深受弯构件 受剪能力 能量平衡理论 尺寸效应