碳纤维布加固锈蚀钢筋混凝土梁的抗弯刚度

利用外加电流加速锈蚀法获得锈蚀钢筋混凝土梁,对其粘贴碳纤维布加固后进行受弯试验,并对加固试验梁建立有限元模型,研究其在静力荷载作用下的抗弯刚度和变形能力。结果表明,随钢筋锈蚀率增大,碳纤维布加固锈蚀钢筋混凝土梁的抗弯刚度发生退化,极限变形能力逐渐削弱。粘贴纵向碳纤维布在一定程度上能够提高锈蚀钢筋混凝土梁的抗弯刚度,设置横向U形箍则能有效提高加固体系的整体工作性能。在试验及分析结果基础上,按照传统钢筋混凝土梁截面抗弯刚度解析分析方法的思路,引入钢筋应变综合系数来考虑锈蚀钢筋与混凝土间粘结性能退化对梁抗弯刚度的影响,并根据试验梁和钢筋不同锈蚀程度有限元模型梁的计算刚度进行反推计算,建立了钢筋应变综合系数的计算公式,进而提出了碳纤维布加固锈蚀钢筋混凝土梁抗弯刚度的计算方法。与试验结果及有限元模拟分析结果的比较表明,所提计算方法具有较高的精度。

Flexural stiffness of corroded reinforced concrete beams strengthened with carbon fiber composite sheets

Corroded reinforced concrete beam specimens were artificially made through galvanostatic method and then strengthened with carbon fiber composite sheets.Bending tests were conducted followed by finite element analysis to study flexural stiffness and deformation performance of strengthened corroded beams.Degradation of flexural stiffness and reduction of deformability can be observed on the strengthened beams with corrosion propagation.Application of carbon fiber composite sheets can restore the flexural stiffness to a certain extent,while transverse U-strips can largely enhance the structural integrity of the strengthening system.Based on the test and analytic results,a compositive coefficient concerning the strain of corroded steel bars was proposed to take into account the influence of bond degradation between corroded steel bars and concrete,which can be determined through an empirical model established from backward analysis of measured stiffness of experimental beams and numerical beams with different corrosion levels.With this coefficient introduced,the computing method for sectional flexural stiffness of strengthened and corroded RC beams was established following conventional analytical method for RC beams.Comparing with the testing and the numerical results,it can be concluded that the method proposed is reasonable for the calculation of flexural stiffness of corroded RC beams strengthened with carbon fiber sheets.