钢筋混凝土构件受弯性能分析与尺寸效应

发布时间：2018-01-14 02:28

本文关键词：钢筋混凝土构件受弯性能分析与尺寸效应　出处：《大连理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：混凝土是一种准脆性材料,其名义强度具有尺寸效应。随着大跨度结构的发展,构件尺寸越来越大,高强混凝土也得到广泛的应用,学者们开始认识到构件尺寸效应的问题并展开了相关研究。在过去的几十年中,学者们对于钢筋混凝土梁受弯性能进行了大量的试验研究和理论研究,但是对于钢筋混凝土梁的受弯性能是否存在尺寸效应这一问题尚存在争议。此外,目前对于配置双筋的高强钢筋混凝土梁的受弯性能特别是变形性能研究还尚不够充分。本文在课题组其他成员的试验研究基础上,针对钢筋混凝土梁的受弯承载能力、变形能力以及相关的尺寸效应问题,开展了相应的数值模拟研究,主要工作如下： (1)在平截面假定的基础上,建立了受弯构件屈服弯矩和极限弯矩的简化计算公式,讨论了钢筋混凝土梁极限状态的判定依据；在确定屈服弯矩和极限弯矩的基础上,采用理想二折线弯矩-曲率关系计算构件位移。在极限弯矩计算中,分别考虑了保护层混凝土剥落导致构件达到极限受弯承载力和保护层混凝土退出工作后核心区受压的考虑箍筋约束作用的混凝上发生破坏两种情况。采用多种约束模型对保护层脱落后核心区受压混凝土破坏情况下的构件极限弯矩进行计算。计算结果表明,不同的约束混凝土模型均能够较好地预测受弯构件的屈服弯矩、极限弯矩以及相应的屈服变形；不同尺寸试件的名义屈服弯矩、名义极限弯矩计算值没有表现出明显的尺寸效应,与试验所观察到的规律一致。但对于试件的极限变形和塑性转角的计算,各种约束混凝土模型的误差均较大,远远高于试验值。其中,Biskinis2007模型考虑了受压区高度对混凝土极限应变的影响,考虑曲率及塑性长度计算得到的塑性转动能力和位移延性系数随试件高度的增加而减小。说明采用Biskinis2007模型在有可能一定程度上体现出试验中得到的构件塑性转动能力的尺寸效应规律。 (2)采用Matlab编制了钢筋混凝土受弯构件承载力和变形分析程序。首先采用分层法计算截面的弯矩-曲率全曲线,然后将梁分为有限结点,用数值积分的方法通过调用弯矩-曲率计算结果得到各个结点的转角及位移。截面分析中,保护层混凝上及核心区受压混凝土分别采用不同的应力-应变关系。为了考察不同约束模型对计算结果的影响,核心区受压混凝土采用了四种约束混凝土模型,分别为Mander模型、Razvi模型、M.Akiyama模型和重叠裂缝模型(overlapping crack model)。其中,M.Akiyama模型和重叠裂缝模型在断裂力学的基础上,考虑了混凝土受压的尺寸效应(长度效应)。采用编制的程序对试件进行分析,结果表明,不同模型均能很好地预测受弯构件的开裂弯矩、屈服弯矩、极限弯矩和屈服位移；不同尺寸试件的名义开裂弯矩、名义屈服弯矩、名义极限弯矩的模拟值没有表现出明显的尺寸效应,与试验所观察到的结论一致。塑性转角和极限位移的模拟值误差较大,M.Akiyama模型和重叠裂缝模型能够较好的体现塑性转角和位移延性的尺寸效应现象,Mander模型、Razvi模型则没有体现出明显的尺寸效应。对于极限变形和塑性转角的计算,简化公式计算精度较差,与简化公式相比,截面分析方法的计算精度有明显提高。
[Abstract]:Concrete is a quasi brittle material, and its strength is size dependent. With the development of large span structure, the component size is more and more big, the high-strength concrete is widely used, scholars have begun to realize that the component size effect problem and related research has been carried out. In the past few decades, scholars have done experimental research and theoretical researches on the performance of reinforced concrete beams, but for reinforced concrete beam flexural performance if there is a size effect is still controversial. In addition, the high strength reinforced concrete beam double reinforced flexural performance especially deformation performance research is still not enough. Based on the experimental study based on the other members of the research group, according to the reinforced concrete beam flexural bearing capacity, deformation capacity and size effect of related issues, to carry out the numerical simulation The main work is as follows:
(1) based on the assumption of plane section, a simplified calculation formula of flexural yielding moment and ultimate moment is established, discussed the basis for determining the limit state of reinforced concrete beams; based on determining the yield moment and ultimate moment, the relation between the ideal of two line moment curvature calculation. In the calculation of ultimate moment displacement component in considering the concrete cover spalling caused flexural members reached the limit of two kinds of damage and protective layer of concrete after exit core area compression considering the restraint effect of stirrups on coagulation using multi constraint model. The ultimate moment of coverdropping after compression failure of concrete core area condition. Results show that different models of confined concrete were able to predict the bending yield moment, ultimate moment and the corresponding yield deformation; Specimen with different size and nominal yield moment, ultimate moment calculation of nominal values did not show obvious size effect, consistent with the observed test. But for the calculation of limit of specimen deformation and the plastic rotation error, all kinds of confined concrete models are large, far higher than the experimental value. Among them, Biskinis2007 model considering the influence of the height of compression zone of concrete ultimate strain, plastic rotation capacity and displacement ductility coefficient with the height of the specimen decreases with the increase of the curvature and the length of plastic is calculated considering. Using Biskinis2007 model to reflect the size effect law of component plastic rotation capacity test in May to a certain extent.
(2) developed by Matlab reinforced concrete flexural members bearing capacity and deformation analysis procedure. First moment calculation section stratified curvature curve, then the beam is divided into finite nodes, the angle and the displacement of each node by numerical integral method by using moment curvature calculation. The section analysis. Cover concrete and confined core concrete with different stress-strain relationship. In order to investigate the constraint model on the calculation result, the core area of compressive concrete adopts four confined concrete models, respectively, Mander model, Razvi model, M.Akiyama model and overlapping crack model (overlapping crack model)., M.Akiyama model and overlapping crack model based on fracture mechanics, considering the size effect of concrete compression (length effect). The specimens were divided by the program Analysis results show that different models can well predict the cracking moment, bending yield moment, ultimate moment and yield displacement; different dimensions of test pieces of the nominal cracking moment, nominal yield moment, ultimate moment simulation of nominal values did not show obvious size effect should be observed, and the test conclusion consistent. Simulation of plastic rotation and ultimate displacement error is larger, the M.Akiyama model and overlapping crack model can better reflect the plastic rotation and displacement ductility of the size effect, Mander model, Razvi model shows no obvious size effect. For calculating the ultimate deformation and plastic rotation, the simplified calculation formula of accuracy and compared with the simplified formula, cross section analysis methods have improved significantly.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU375

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