粘贴预应力碳纤维布钢梁的放张效应

Effect of Releasing Pretension for Steel Beams Bonded with Prestressed Carbon Fiber Sheet

基于线弹性物理关系假定和变形协调关系,推导了粘贴预应力片材加固梁张拉力释放后片材预应力和胶层剪应力的分布方程,得到了梁的有效预应力及预应力损失计算公式,并且按共轭梁法推导了预应力引起的反拱计算公式;利用自主开发的一套简易的张拉锚固装置对碳纤维布施加预应力,然后与工字型钢试验梁粘贴,待胶固化后进行粘贴预应力碳纤维布加固钢梁的放张试验。分析结果表明:试验结果与计算结果吻合很好,理论分析结果具有合理性和正确性,为深入研发预应力碳纤维片材加固技术并建立相关的设计理论奠定了基础。

The effect of releasing pretension was investigated for flexural members externally bonded with prestressed laminate.Based on the assumption of linear elastic physical relationship and the compatibility of deformation,the equations of distribution were derived for stresses of laminate,respectively on interface and at cross sections of a beam.The calculation formulae were obtained for effective prestress and prestress loss.The calculation formulas of camber deflection were deduced by adopting the method of conjugate beam.A set of easy prestressing devices was developed to exert pretension to carbon fiber sheet.The prestressed strip was mechanically anchored at both ends and then bonded to a steel beam with I-shaped section.After the adhesive dried the mechanical anchor was loosed,the effect of releasing pretension was measured.Analysis results show that the test results agree well with the calculated results,and the rationality and correctness of the theoretical expressions are verified.This will serve as the foundation for the further development of strengthening technology with prestressed carbon fiber sheet and establishment of the related design theory.