A Study of Properties and Prediction of Long-term Deformation of Reinforced Concrete Members

钢筋混凝土构件的性能及长期变形预测研究

基本信息

批准号：
01550372
负责人：
SATO Ryoichi
金额：
$ 1.09万
依托单位：
Utsunomiya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550372/
关键词：
Reinforced Concrete Long-term Deformation Creep Drying Shrinkage Bond Slip Stress Hysteresis

项目摘要

This study develops a new numerical method for prediction of reinforced concrete members subjected to not only constant but also variable sustained bending moments in order to help establish design method of long-term deformation. The calculated results are compared with the results obtained from the experiment in which the effects of both magnitude and hysteresis of sustained loads are mainly investigated.The following conclusions are drawn from these theoretical and experimental studies ;1. The basic differential equations to analyze the time-dependent deformation of reinforced concrete members are formulated in active bond zone taking stress hysteresis in concrete due to creep, drying shrinkage, creep of bond and drop of bond strength near the cracked section into account.2. The present method can predict the time-dependent average curvature, compressive strain in concrete, reinforcement strain of reinforced concrete members subjected to variable sustained loads as well as subjected to constant sustained loads.3. Average curvature observed at 250 days after loading in reinforced concrete member subjected to constant sustained load 30 % larger than that subjected to variable sustained load shows the necessity considering the influence of stress history of concrete in estimating deformation.4. Time-dependent increase of crack width can be explained by small decrease of bond stress, increase of bond slip and that of drying shrinkage.5. The maximum differences between stress calculated by considering the history and that by using effective modulus method are about 10 % in the case subjected to constant sustained load and 20 % in the case subjected to variable sustained load, respectively.

这项研究开发了一种新的数值方法，用于预测钢筋混凝土成员不仅要持续恒定，而且受到可变的持续弯曲力矩的影响，以帮助建立长期变形的设计方法。将计算的结果与从实验中获得的结果进行了比较，在这些实验中，主要研究了次级和滞后的影响。从这些理论和实验研究中得出以下结论； 1。分析钢筋混凝土构件的时间依赖性变形的基本微分方程是在活跃的键区中提出的，这是由于蠕变，干燥收缩，粘结的收缩，粘结蠕动和键盘强度下降的分解部分附近的粘结而在混凝土中进行了应力滞后。目前的方法可以预测时间依赖的平均曲率，混凝土中的压缩应变，钢筋混凝土构件的钢筋应变，受到可变持续负载的且受到恒定持续负载的影响。3。在加载后250天观察到的平均曲率在固定持续负荷受到恒定持续负载的约为持续负载的持续载荷大30％大30％，这表明考虑到混凝土在估计变形中的应力历史的影响，其必要性。4。裂纹宽度的时间依赖性增加可以通过键应力的较小减少，键滑的增加和干燥收缩的较小。5。通过考虑历史和使用有效模量法计算的压力之间的最大差异约为持续持续负荷的10％，在持续持续负载和20％的情况下分别受到可变的持续负载。