高强混凝土无腹筋梁不同破坏形态受剪性能试验研究

Experimental study on shear behavior of high-strength concrete beams without web reinforcement in different failure patterns

为研究不同剪切破坏形态高强混凝土无腹筋梁的受剪性能,以剪跨比和截面有效高度为主要参数,开展了9根混凝土强度等级为C90的高强混凝土无腹筋梁试件在集中荷载作用下的受剪性能试验,分析了试件的剪切破坏形态、剪切性能状态以及对应的名义剪切强度。根据试验现象和试件受力特点,发现斜拉破坏试件以主斜裂缝的出现为主要破坏标志,剪压和斜压破坏试件以受压区混凝土的压碎为主要破坏标志。对名义剪切强度的分析表明:名义剪切开裂强度受剪跨比和截面有效高度的共同影响,而名义剪切破坏强度则主要受剪跨比影响;名义剪切开裂强度和名义剪切破坏强度可分别采用混凝土的抗拉强度和抗压强度进行表征。通过对国内外相关规范中的受剪承载力计算公式进行适用性分析,建议在确定高强混凝土无腹筋梁的受剪承载力时应以剪切开裂作为控制状态,同时应考虑构件尺寸效应的影响以提高计算的准确性。

To investigate the shear behavior of high-strength concrete beams without web reinforcement in different failure patterns,this study conducted shear behavior tests on nine high-strength concrete beams(with a concrete strength grade of C90)subjected to concentrated loads,while considering the shear-span ratio and the effective depth of section as main parameters.The failure pattern,performance state and coresponding nominal shear strength of the specimens were analyzed.Based on experimental observations and load-bearing characteristics of specimens,it was found that the main failure sign was the appearance of main inclined cracks in the diagonal-tensile specimens,and the crushing of concrete in the compression zone was the main failure sign in the shear-compressive and diagonal-compressive failure specimens.The analysis of nominal shear strength reveals that the joint influence of shear-span ratio and effective depth of section is observed on the nominal shear-splitting strength,while the predominant factor affecting the nominal shear-failure strength is the shear-span ratio.The nominal shear-splitting strength and the nominal shear-failure strength can be determined based on the tensile and compressive strengths of concrete,respectively.The shear capacity evaluation should prioritize shear-splitting as the governing state,based on a comprehensive analysis of both domestic and foreign design standards.Furthermore,it is crucial to thoroughly consider the size effects in order to enhance the accuracy of the assessment.