共查询到14条相似文献,搜索用时 109 毫秒
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用双剪强度理论解混凝土板冲切的轴对称问题 总被引:19,自引:6,他引:13
本文采用双剪强度理论,对混凝土板轴对称冲切破坏强度进行了计算。采用刚塑性模型,给出轴对称破坏机构,得到极限应力圆的包络线为二条直线,再利用虚功方程求得破坏荷载的上限。公式形式简单,与已有结果相比符合很好。 相似文献
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弹丸冲击贯穿有限厚混凝土材料靶板的背面成坑效应 总被引:1,自引:1,他引:0
弹丸冲击贯穿有限厚混凝土靶板后,靶板背面有大块的混凝土剥落,形成近似的锥形坑。为了研究背面弹坑半锥角θ这一作为混凝土靶板贯穿后破坏范围问题研究中的重要参量,将贯穿问题等效为轴对称条件下的冲切破坏问题。采用双剪应力三参数强度准则及刚塑性模型,得到了极限应力圆的包络线方程,给出了轴对称破坏机构,进而求得θ值的表达式。理论计算结果与数值模拟结果、实验数据三者之间吻合度较好。研究表明,θ值由混凝土材料抗压强度与抗拉强度比值决定。基于上述研究,提出在混凝土中掺加钢纤维以提高有限厚靶板抗贯穿能力的实际方法,并进行了弹道实验。实验结果表明,贯穿破坏后靶板碎片的数量及θ大幅降低,显示了高含量异型钢纤维混凝土在抗贯穿方面的适用性。 相似文献
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基于双剪强度理论的混凝土板极限冲切承载力计算方法 总被引:6,自引:0,他引:6
将混凝土板的冲切破坏简化为平面应变问题,采用双剪应力三参数强度准则对冲切破坏时的混凝土板剪压区的复合应力进行分析,得到了剪压面上的极限竖向剪应力,利用静力平衡条件求得混凝土板的极限冲切承载力计算公式。与国内外246个试件的试验数据进行比较表明,该公式的计算结果与试验结果吻合良好。计算公式的计算模式概念清晰,可供结构设计时参考。 相似文献
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钢筋混凝土结构冲切与剪切问题取得了大量的研究成果,由于问题本身的复杂性,所以至今仍未能找到一个令人满意的预测冲剪强度及破坏模式的办法。本文通过试验研究来探索冲切破坏与剪切破坏的本质,是目前较为可行的办法。为此在试验研究的基础上,对这一问题进行了系统的总结与研究。 相似文献
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A simple analytical model is presented to predict the ultimate punching shear strength of slab–column connections. The model is based on the physical behavior of the connections under load, and is therefore applicable to both lightweight and normal weight concrete. The model assumes that punching is a form of combined shearing and splitting, occurring without concrete crushing, but under complex three dimensional stresses. Failure is then assumed to occur when the tensile splitting strength of the concrete is exceeded. The theory is applied to predict the ultimate punching shear strength of 60 slab–column connections reported recently in literature, and designed to fail in shear, involving a large number of variables, such as type of concrete, concrete strength, tension steel ratio, compression reinforcement and loaded area. The results show very good agreement between the predicted and experimental values. The uniqueness of the model is that it incorporates many physical characteristics of the slabs and their failure behavior, and this is reflected by its ability to predict extremely well the results of tests conducted by researchers other than the authors. 相似文献
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The present paper deals with the experimental assessment of the effectiveness of steel fibre reinforcement in terms of punching resistance of centrically loaded flat slabs, and to the development of an analytical model capable of predicting the punching behaviour of this type of structures. For this purpose, eight slabs of 2550 × 2550 × 150 mm3 dimensions were tested up to failure, by investigating the influence of the content of steel fibres (0, 60, 75 and 90 kg/m3) and concrete strength class (50 and 70 MPa). Two reference slabs without fibre reinforcement, one for each concrete strength class, and one slab for each fibre content and each strength class compose the experimental program. All slabs were flexurally reinforced with a grid of ribbed steel bars in a percentage to assure punching failure mode for the reference slabs. Hooked ends steel fibres provided the unique shear reinforcement. The results have revealed that steel fibres are very effective in converting brittle punching failure into ductile flexural failure, by increasing both the ultimate load and deflection, as long as adequate fibre reinforcement is assured. An analytical model was developed based on the most recent concepts proposed by the fib Mode Code 2010 for predicting the punching resistance of flat slabs and for the characterization of the behaviour of fibre reinforced concrete. The most refined version of this model was capable of predicting the punching resistance of the tested slabs with excellent accuracy and coefficient of variation of about 5%. 相似文献