钢筋混凝土结构极限承载力分析的非线性有限元法

【作者】 张海龙；

【导师】 杨炳成；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2005， 硕士

【摘要】 随着交通事业的日益发展,大量新建桥梁的承载力需要评定;同时大量的现役桥梁需要进行荷载提升或维修加固,为此对现役桥梁的承载力评估也显得日益重要起来。目前采用有限元方法分析桥梁结构极限承载力的方法中,对受力性能复杂的混凝土材料,基本上是通过实验数据回归拟合得到混凝土的本构关系和破坏准则。由于材料本身性质的复杂性,各种有限元模型都存在或多或少的缺陷,导致计算结果偏差较大,适用范围有限。另外,现行的公路桥涵设计规范,在对桥梁受弯构件承载能力计算中采用了一些基本假定,导致计算结果偏于安全。 本文在国内外关于钢筋混凝土结构非线性分析的研究基础上,采用分离式有限元模型对钢筋混凝土结构进行非线性有限元分析。本文采用C++Builder6.0,通过面向对象的方法设计出非线性分析程序。该程序包含非线性计算类、混凝土单元类、钢筋单元类、粘结单元类。这种面向对象的方法,使得复杂的钢筋混凝土有限元分析程序在调试中出现的错误仅限于类的局部,易于排除,程序编制后易于维护。本程序可对钢筋混凝土结构进行非线性有限元分析,模拟构件从加载到破坏的全过程,可得出梁的荷载—挠度曲线、弯矩—曲率曲线以及在不同加载阶段各截面的应力、应变值。笔者将程序计算结果与实验数据相比较,发现两者吻合的较好,从而验证了本程序计算结果的可靠性;同时又利用现行公路桥涵设计规范对该试验梁进行极限承载力计算,经比较表明规范计算值偏于保守。更多还原

【Abstract】 With the development of communication, a great deal of new-build bridges need to be evaluated, at the same time, a great deal of service bridges need to be load exalted or maintained and reinforcement, which makes it important to evaluate the service bridges’ bearing capacity. At present, kinds of methods of finite-element analyzing bridge structure’s limit bearing capacity for concrete’s complex stress nature get the concrete’s constitutive equations and destructive criterion by fitting regression line. Kinds of finite-element models have more or less deficiency for the material’s complex character, which leads to the bigger deviation of the calculated numeric value, so it is limited in the range. Besides, the current bridge and culvert design criterion takes some basic postulation during the calculation of the bridge’s member in bending, which results in over-conservative numeric value.Based on the nonlinear analysis researches of concrete structure at home and abroad, material nonlinear analysis of reinforced concrete beams were done by model in this thesis. An increment-tangent stiffness iteration method program was done by using the above theory and the C++Builder 6.0.The process from loading to failure was simulated, and the load-deflection curve, moment-curvature curve, and strains of element sections at different locations were got in loading stages. The results analysis was done. The computed results were exported to "txt"files. Graph post process was done, and figures showed the changes of stresses and strains on beam section visually.The computed results coincided with the experimental data, so the feasibility of the method in this thesis was proved. The results can be used as reference by researchers and structural designers and had practical value to some value extent.更多还原