粘钢法加固RC梁受扭承载力的计算方法与数值分析

Calculation Method and Numerical Analysis of Torsional Bearing Capacity of RC Beams Strengthened by Bonding Steel Plate Method

粘钢法是一种常用的加固方法,规范中明确规定了粘钢法加固钢筋混凝土梁(RC梁)的受弯与受剪承载力公式,但对受扭承载力公式并未涉及。为了研究粘钢加固RC梁受扭承载力的计算方法,首先借助剪力流理论与变角度空间桁架模型(VASTM),分别推导出RC梁与粘钢法加固RC梁受扭承载力的计算公式。然后探讨了加固前后RC梁配筋强度比ζ与ζ′的变化情况,在此基础上进一步提供了加固工程算例。最后借助ANSYS软件建立了两种不同方案的粘钢法加固模型,研究了其在扭矩作用下的动力响应与破坏形态。研究结果表明,粘钢法加固受扭RC梁加固前后配筋强度比ζ与ζ′变化很小,钢板厚度为1 mm时其受扭承载力提高约89%;扭矩较小时可采用在RC梁两端粘贴钢板进行加固;扭矩较大时出现梁柱节点先于构件破坏的情况,应将钢板粘贴区域扩大至梁柱节点,但此时不再符合VASTM。

Bonding steel plate method is a common reinforcement method,the formulas of flexural and shear bearing capacity of reinforced concrete beams(RC beams)strengthened by this method are clearly stipulated in the code,but the torsional bearing capacity formula is not involved.In order to study the calculation method of torsional bearing capacity,firstly,with the help of shear flow theory and variable angle space truss model(VASTM),the formulas for calculating the torsional capacity both of RC beams and strengthened-RC beams were deduced respectively.Then the change of the ratiosζandζ′of RC beams before and after strengthening was discussed.On this basis,an engineering example of torsion strengthening was further provided.Finally,two different reinforcement models of bonding steel plate method were established by ANSYS software,and the dynamic response and failure modes under the torque were studied.The results show that the change of ratiosζandζ′is little before and after the reinforcement for RC beams subjected to torsion,and the torsion bearing capacity increases about 89%when thickness of steel plate is 1 mm.When the torque is small,the RC beam can be reinforced by bonding steel plates at both ends of RC beams;When the torque is large,the beam-column joint will be destroyed before the member,and the steel plate adhesion area should be expanded to the beam-column joint,at this time,it is no longer conforms to VASTM.