混凝土徐变预测模型修正分析*
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（1 湖南城市学院土木工程学院，益阳 413000；2 湖南科技大学土木工程学院，湘潭 411105）［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。［关键词］预测模型; 混凝土圆柱; 徐变系数; 理论分析; 试验研究中图分类号：TU528.1 文献标识码：A 文章编号：1002-848X(2014)05-0045-05Correction analysis on prediction model of concrete creepCao Guohui1, Hu Jiaxing2, Zhang Kai1, He Min1(1 College of Civil Engineering, Hunan City University, Yiyang 413000, China; 2 College of Civil Engineering, Hunan University of Science and Technology, Xiangtan 411105, China)Abstract: 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.Keywords: prediction model; concrete circular column; creep coefficient; theoretical analysis; experimental study*湖南省高等学校科学研究项目（重点项目）(12A027)。作者简介：曹国辉，博士，教授，Email: cgfcivil@163.com。参考文献［1］桂海清. 混凝土早期收缩与抗裂性能试验研究［D］. 杭州：浙江大学, 2004: 5-9.［2］杨小兵. 混凝土收缩徐变预测模型研究［D］. 武汉: 武汉大学, 2004: 15-48.［3］林波. 混凝土收缩徐变及其效应的计算分析和试验研究［D］. 南京: 东南大学, 2004: 15-48.［4］NEVILLE A M, DILGER W H, BROOKS J J. Creep of plain and structure concrete［M］. London: Construction Press, 1983.［5］BAZANT Z P, BAWEJA S. Creep and shrinkage prediction model for analysis and design of concrete structures-model B3［J］. Material and Structures, 1995，28（6): 357-365.［6］ACI Committee 209. Prediction of creep, shrinkage, and temperature effects in concrete structures［M］. Houston: America Concrete Institute, 1992.［7］张克波, 许康, 吕毅, 等. 配筋混凝土柱徐变试验［J］. 长沙理工大学学报：自然科学版, 2011, 8(2): 17-20.［8］JTG D62—2004 公路钢筋混凝土及预应力混凝土桥涵设计规范［S］. 北京: 人民交通出版社, 2004.［9］CEB-FIP mode code 1990［S］. London:Thomas Telford Services Ltd.,1993.［10］刘立新，赵静超，王俊. 折线先张预应力混凝土简支梁徐变挠度试验研究［J］. 建筑结构, 2009,39(S2): 117-120.［11］BAZANT Z P, BAWEJA S. Justification and refinements of model B3 for concrete creep and shrinkage［J］. Materials and Structures, 1995,28(7): 488-495.
