Study on Control of Crack Width in Reinforced Concrete Members under Sustained Loading

持续荷载作用下钢筋混凝土构件裂缝宽度控制研究

基本信息

批准号：
12650561
负责人：
KONDO Goro
金额：
$ 2.18万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

In this study, experiments were performed on reinforce concrete beams under static loading and sustained loading, to investigate the influence of mechanical properties of concrete on flexural crack behavior. From the results of these experiments, use of high-strength concrete does not influence significantly on crack width under static loading, though it makes crack spacing larger. However, under sustained loading, it is efficient for control of crack width, because of low drying shrinkage and high tensile strength of high-strength concrete. To evaluate the influence of material properties such as drying shrinkage, creep of concrete and time effect of bond between reinforcements and concrete, finite element analysis was applied to the specimens under sustained loading. Analytical results showed that though volume change of concrete most influences on increase of crack width under sustained loading, bond characteristics near the crack surface have comparable effect.To improve the estimation of crack width, pull out test were carried out and cone-failure near the concrete surface was analyzed by finite element method. From the analytical results, bond degradation near the concrete surface was represented by tracing conic crack growth.To investigate the bond-slip relationship under sustained loading, bond tests using pull-out specimen were carried out. From the test results, the effects of deformed shape on reinforcement were evaluated and generalized bond-slip relationship were derived.

在这项研究中，在静态载荷和持续负荷下对钢筋混凝土梁进行了实验，以研究混凝土的机械性能对弯曲裂纹行为的影响。从这些实验的结果来看，使用高强度混凝土在静态载荷下对裂纹宽度没有显着影响，尽管它使裂纹间距更大。但是，在持续的负载下，由于低干燥混凝土的干燥收缩和高拉伸强度，它可以有效地控制裂纹宽度。为了评估材料特性的影响，例如干燥收缩，混凝土的蠕变以及钢筋和混凝土之间键的时间效应，将有限元分析应用于持续负载下的样品。分析结果表明，尽管混凝土的体积变化最大的影响对持续负荷下的裂纹宽度增加，但裂纹表面附近的键特性具有可比的效果。为了改善裂纹宽度的估计，进行了拔出测试，并在附近进行锥形锥形。通过有限元法分析混凝土表面。从分析结果中，通过追踪圆锥裂纹的生长来表示混凝土表面附近的键降解。为了研究持续负载下的键滑关系，进行了使用拉出标本的键检验。从测试结果中，评估了变形形状对加固的影响，并得出了广义滑移关系。