粘结层和预应力对CFRP板加固损伤钢梁抗弯性能的影响

Effects of the adhesive layer and prestress on the flexural behavior of damaged steel beams strengthened with CFRP plates

为了对比粘结层和预应力对碳纤维增强聚合物复合材料(CFRP)板加固损伤钢梁抗弯性能的影响,进行了5根H型损伤钢梁的抗弯试验,分析了特征荷载、荷载-挠度曲线、CFRP板应变及其强度利用率的变化。试验结果表明:有粘结和无粘结CFRP板具有相近的加固效果,特征荷载差值小于2%;非预应力CFRP板在正常使用阶段的加固效果很小,而预应力CFRP板加固钢梁的特征荷载比非预应力CFRP板提高了近30%。平截面假定适用于有粘结CFRP板-钢梁复合截面,而不适用于无粘结CFRP板-钢梁复合截面。相比于非预应力CFRP板,对CFRP板施加预应力可以显著提高CFRP板的强度利用率。建立的有限元模型可以较好地预测试件的抗弯性能,增加CFRP板的预应力、厚度和弹性模量可以提高损伤钢梁的抗弯加固效果。

In order to investigate the effects of the adhesive layer and prestress on the flexural behavior of damaged steel beams strengthened with carbon fiber reinforced polymer(CFRP)plates,five damaged H-steel beams were tested under flexure.The characteristic load,load-deflection curve,CFRP plate strain and its strength utilization were analyzed.Test results show that the unbonded CFRP plate has a similar strengthening efficiency to the bonded CFRP plate,with a difference of less than 2%in the characteristic loads.The non-prestressed CFRP plate provides only a very small strengthening efficiency under the normal service state.However,the characteristic loads of steel beams strengthened with the prestressed CFRP plate can be significantly increased by about 30%compared with the non-prestressed CFRP plate.The plane section assumption is satisfied in the bonded CFRP platesteel beam composite section while it is not satisfied in the unbonded CFRP plate-steel beam composite section.Compared with the non-prestressed CFRP plate,the strength utilization of the CFRP plate can be obviously increased when a prestress is applied in the CFRP plate.The developed finite element model can predict the flexural behavior of the specimens with good accuracy.The increase in the prestress,thickness and elastic modulus of the CFRP plate can increase the flexural strengthening efficiency of damaged steel beams.