CFRP拉索变刚度黏结型锚固系统受力性能研究

Mechanical properties of CFRP cable bonded anchorage system with variable stiffness

碳纤维增强复合材料(CFRP)与钢材相比具有轻质高强、耐腐蚀、耐疲劳、蠕变小及温度敏感性低等优势,可替代传统钢索用于桥梁结构以提升桥梁跨度及服役寿命。但是,由于CFRP为正交各向异性材料,导致CFRP索难以锚固。为此,提出了一种变刚度黏结剂与弯折索体结合的锚固系统,通过理论分析、有限元模拟及试验验证等方法研究了锚固系统的承载性能。结果表明:相比于传统的CFRP平行索锚系统,弯折索锚系统可明显提高锚固承载力及降低索锚滑移量,变刚度黏结介质可明显降低锚具加载端应力集中现象,避免拉索的局部断裂;当CFRP拉索(19根筋)弯折角为4°,黏结材料弹性模量范围为8~18 GPa时,锚固效率达96%,拉索所受压应力和剪应力峰值分别降低约48%和64%。

Compared with steel,carbon fiber reinforced polymer(CFRP)has the advantages of light weight,high strength,corrosion and fatigue resistances,low creep and temperature sensitivity.It can replace the traditional steel cables used in bridge structures to improve the span and service life.However,CFRP is an orthotropic material,which leads to the difficulty of anchoring CFRP cables.In this paper,a new type of composite cable anchorage system of CFRP with variable stiffness bonding material and bent cable was proposed to solve the problem of difficult anchoring of CFRP cables.The load-bearing performance of the anchorage system was systematically studied by theoretical analysis,finite element simulation and experimental verification.The results show that compared with the traditional CFRP parallel cable anchorage system,the bending cable anchorage system can significantly improve the anchoring capacity and reduce the slip of the cable anchor,and the variable stiffness bonding medium can significantly reduce the stress concentration at the loading end of the anchor and avoid the local fracture of the cable.When the bending angle of CFRP cable(19 tendons)is 4°and the elastic modulus of bonding material ranges from 8 GPa to 18 GPa,the anchorage efficiency approaches up to 96%,and the peak compressive stress and shear stress of the cable are reduced by 48%and 64%,respectively.