CFRP加固不同箍筋间距高强混凝土柱延性试验

Experimental Study on Ductility of CFRP-Confined High Strength Concrete Columns with Different Stirrup Spacing

目的研究碳纤维(CFRP)布横向包裹加固两种在塑性铰区具有不同箍筋间距柱的延性性能.方法设计并制作了4个高强混凝土柱,对柱施加水平低周反复荷载,对比不同箍筋间距柱在加固前后的延性系数、能量耗散能力和刚度退化等情况,通过引入总体折算体积配箍特征值将柱构件所受外部约束定量化,比较试件所受的约束效果.结果在经过CFRP布加固后,塑性铰区箍筋间距较大(150 mm)柱的延性系数要大于箍筋间距较小(100 mm)未加固的柱,但仍然低于箍筋间距较小的加固后柱.试件的总体折算体积配箍特征值越大,所受外部约束越强,延性越好.结论在实际加固工程中,可以利用CFRP布横向加固方式来弥补柱构件因各种人为原因造成塑性铰区箍筋间距增大而损失的延性性能,加固后可以使其超过无箍筋缺陷时的延性水平.

The purpose of the paper is researching ductility behavior of two kinds of CFRP-confined columns with different stirrup spacing in the plastic hinge zone. Based on the test data of four high strength concrete columns tested under low-frequency cyclic lateral loading, the ductility coefficient, energy dissipation and stiffness degradation were compared. In order to quantify the confinement provided by the stirrups and CFRP sheets and compare the confinement effect between different columns, the parameter Ao was defined in this paper. The results show that the CFRP-confined column with larger stirrup spacing（ 150 mm）exhibits higher ductility performance than the contrast column with smaller stirrup spacing（ 100 mm）, but has lower ductility behavior than the CFRP-confined column with larger stirrup spacing. Along with the increase of the parame- ter A e value, the confinement caused by the stirrups and CFRP sheets is becoming stronger and stronger and the column ductility behavior is becoming better and better. In the actual strengthening project, when the hu- man factors cause the stirrup spacing of column increased in the plastic hinge zone, the method of the wrapped CFRP sheets can be used to remedy the insufficient ductility, the ductility of strengthened column can exceed the level of column with no stirrup defects.