摘要
对不同加载龄期的混凝土圆柱体进行长期徐变试验,结果表明混凝土圆柱体内徐变系数较体外徐变系数普遍偏小,加载龄期对混凝土体外徐变系数影响较大,对体内徐变系数影响较小。国内外徐变预测模型对短期加载龄期(9d)的徐变系数预测精度较高,对长期加载龄期(39d)的徐变系数预测精度较差,特别是对后期徐变系数预测普遍不足。GZ(1993)模型对徐变初期预测存在不连续现象,但整体预测效果最好。CEB-FIP(1990)模型预测效果最差,预测徐变系数的变化规律与实测值偏离较大。采用最小二乘法对实测数据进行非线性回归分析,分析表明CEB-FIP(1990)模型对名义徐变系数预测偏低,这主要是由CEB-FIP(1990)模型中加载龄期影响系数预测偏低造成的。根据不同加载龄期的徐变系数实测值,对CEB-FIP(1990)模型进行了修正,从而大大提高了徐变预测模型的预测精度。
Long-term creep experiment of concrete circular columns with different loading ages was done. The experimental result shows that internal creep coefficient is generally smaller than external creep coefficient, the loading age has great influence on external creep coefficient and little influence on internal creep coefficient. The creep prediction models at home and abroad with short-term loading age （9d） have high predictive accuracy for creep coefficient. The creep prediction models at home and abroad with long-term loading age（39d） have low predictive accuracy for creep coefficient, especially predicted values of creep coefficient are general insufficient in late stage. GZ（1993） model has discontinuous phenomenon for forecasting initial creep coefficient, but predictive effect is best. The predictive effect of CEB-FIP（1990） model is worst, the change rule of predicted values of creep coefficient deviates from measured values. The method of least squares for nonlinear regression analysis of measured data was adopted. The analysis result shows that CEB-FIP（1990） model has low prediction for nominal creep coefficient, and this phenomenon is large due to low prediction for influence coefficient of loading age. According to measured values of creep coefficient with different loading ages, CEB-FIP （1990） model of concrete creep is corrected, which can greatly improve the predictive accuracy of creep prediction model.
出处
《建筑结构》
CSCD
北大核心
2014年第5期45-49,共5页
Building Structure
基金
湖南省高等学校科学研究项目(重点项目)(12A027)
关键词
预测模型
混凝土圆柱
徐变系数
理论分析
试验研究
prediction model
concrete circular column
creep coefficient
theoretical analysis
experimental study
