体外配置CFRP筋预应力混凝土箱梁收缩徐变效应分析

以体外配置CFRP筋预应力混凝土箱梁1 001 d的长期受力性能试验为基础,采用徐变换算截面法对收缩徐变效应引起的截面应力重分布规律进行分析。理论分析与试验结果对比表明,徐变换算截面法能较好地分析持续荷载作用部分预应力箱梁的收缩徐变效应。运用双线性法和曲率法对试验箱梁的长期挠曲变形进行预测,两种分析方法预测结果基本一致,建议取长期挠度增长系数为2.45,此时长期挠度变形理论预测值与实测结果吻合较好。对现行设计规范进行有关参数修正后,持续荷载作用下预应力混凝土箱梁的最大裂缝宽度理论值与实测结果吻合较好。研究成果将为CFRP筋在体外预应力箱梁中的推广应用提供参考。

Analysis on Shrinkage and Creep Effect of External Concrete Box Girder Prestressed with CFRP Tendons

Based on 1001 days' experiment of the external concrete box girder prestressed with CFRP tendons,the law of section stress redistribution caused by creep and shrinkage effects is analyzed with the creep transformed-section method.The theoretical analysis is compared with test data.The result shows that the creep transformed-section method is feasible to analyze the shrinkage and creep effect of the partially prestressed concrete box girder under sustained uniform loads.Long-time deflection of the test box girder is predicted applying the bilinear method and curvature method.Both results fit well.The growth factor of long-time deflection is suggested to be 2.45,which facilitates good matching between the predicted and tested values of long-time deflection.The theoretical and measured values of the maximum width of the crack of the concrete prestressed box girder under uniform loads coincide with each other after reclifying relevant parameters of the present design code.The research will be helpful to the expanding application of CFRP tendons in external prestressed concrete box girders.