新型CFRP-UHPC组合管混凝土圆柱轴压性能

Axial compression behavior of novel concrete-filled circular CFRP-UHPC composite tubular columns

为研究超高性能混凝土(UHPC)管替代碳纤维增强聚合物(CFRP)-钢管混凝土组合柱中钢管的可行性,提出一种外部缠绕CFRP的UHPC预制管、内部现浇填充普通混凝土的新型CFRP-UHPC组合管混凝土(Concrete-filled CFRP-UHPC tube,CFFUT)柱。对10个CFFUT圆柱(包含2个对比柱)进行了单调轴压试验,研究了UHPC管壁厚度、CFRP环向包裹层数和核心混凝土强度等的影响规律。结果表明:CFRP-UHPC管可以有效提高组合柱的承载力、变形能力和延性;CFFUT圆柱破坏形态为核心混凝土压溃、UHPC管开裂和CFRP拉断,破坏后整体性较好,属延性破坏模式;CFFUT圆柱的极限承载力与UHPC管壁厚度、CFRP层数和核心混凝土强度呈正相关;延性系数随UHPC管壁厚度、CFRP层数增加而提高,随核心混凝土强度增加先提高后降低。揭示了CFFUT柱的界面增强作用机制,CFFUT柱极限承载力与同等截面普通混凝土柱相比提高93.9%~203.5%,且CFFUT柱极限承载力一定程度上与CFRP-钢管混凝土柱相当。建立了CFFUT圆柱轴压极限承载力理论计算模型,并通过有限元模拟验证,理论值、模拟值和试验结果吻合较好。

In order to study the feasibility of replacing steel tubes of concrete filled carbon fiber-reinforced polymer(CFRP)-steel tube columns with ultra high performance concrete(UHPC)tubes,a novel concrete-filled CFRPUHPC tube(CFFUT)column was proposed.The CFFUT column consists of a combination of UHPC precast tubes externally wrapped with CFRP and an internal cast-in-place filled normal concrete.Ten CFFUT columns,including two contrast columns,were tested under monotonic axial compression,and the influences of UHPC tube thickness,CFRP layer numbers and filled concrete strength were investigated.The results show that CFRP-UHPC tube can effectively improve the bearing capacity,deformation capacity and ductility of composite columns.The failure of CFFUT column is mainly manifested as the collapse of filled concrete,cracking of UHPC tube and rupture of CFRP.The integrity of CFFUT column is good after failure,and it belongs to ductility failure mode.The ultimate bearing capacity of CFFUT column is positively correlated with the thickness of UHPC tube,the number of CFRP layers and the strength of filled concrete.Ductility factor increases with the increase of UHPC tube thickness and CFRP layer number,and increases first and then decreases with the increase of filled concrete strength.The interface strengthening mechanism of CFFUT column is revealed.The ultimate bearing capacity of CFFUT columns is 93.9%-203.5%higher than that of normal concrete columns with the same section,and the ultimate bearing capacity of CFFUT columns is equivalent to that of concrete-filled CFRP-steel tube columns to a certain extent.The theoretical calculation model of ultimate bearing capacity is established and verified by finite element analysis.The calculated and simulated values are in good agreement with the test results.