CFRP丝股新型锚固系统受力分析及试验研究

Stress Analysis and Experimental Research on a New CFRP Wire Strand Anchorage System

为解决CFRP丝股现有内锥形锚具锚固区的径向挤压应力分布不合理及丝股在受荷端存在弯折等问题,研制了双筒黏结型锚具。该新型锚具在传统内锥形锚具内,置入一个带有多条纵向切缝的钢质套管,套管切缝的宽度沿纵向渐变,则套管的径向收缩刚度随之渐变,此举可避免小孔端挤压应力过大,以实现径向挤压应力的合理分布。套管包裹住CFRP丝股,以环氧树脂作为黏结介质,并对锚具进行预紧。利用ANSYS软件对6组不同丝间距和套管壁厚的新型锚具进行受力模拟,得出最优锚具设计尺寸参数,探明了锚固区筋材应力分布情况;制作现有传统内锥形锚具及新型锚具,对19丝Φ5的丝股进行静力拉伸试验,并对各影响因素进行分析。结果表明:新型锚具锚固效率系数可达到110%,相比普通内锥形锚具提高了近30%;丝间距以1~2 mm为宜,丝间距越小锚固性能越好;套管、预紧力对提高锚固性能影响很大,套管的壁厚在4~6 mm为宜,在此范围内壁厚越大,丝间距对锚固性能的影响越弱;预紧力大小约等于锚固系统极限承载力时,锚固效率相对于无预紧作用提高12%。

A double-barrel bonded anchorage was created to address the issues of excessive radial extrusion stress distribution in the anchorage area of the present inner tapered anchorage and bending of the wire strand at the loaded end of the CFRP wire strand.The new anchorage was a steel casing with multiple longitudinal slits placed in a traditional inner cone anchorage.The width of the casing slits gradually changed along the longitudinal direction,so that the radial shrinkage stiffness of the casing gradually changed,avoiding excessive extrusion stress at the small hole end to achieve a reasonable distribution of radial extrusion stress.The casing was wrapped around the CFRP wire strands,using epoxy as the bonding agent,and the anchor was pre-tightened.Using various wire spacings and sleeve wall thicknesses,six sets of new anchorages were simulated using the ANSYS software to determine the ideal anchor design parameters and analyze how the tendons in the anchorage region were stressed.The existing inner cone anchor and new anchor were made,a static tensile test using 19wireΦ5strands was performed,and the influencing factors were analyzed.The results show that the anchoring efficiency coefficient of the new anchor reached 110%,which was approximately 30%higher than that of the ordinary inner cone anchor.The ideal wire spacing was between 1and 2mm;the narrower the wire spacing,the more effective the anchoring.The improvement in the anchoring performance was significantly influenced by the casing and preloading force.The thickness of the casing wall was between 4-6mm,and the thicker the wall in this range,the weaker the effect of wire spacing on the anchoring efficacy.The anchorage efficiency increased by 12%compared to no preload when the size of the preload was approximately equal to the ultimate bearing capacity of the anchorage system.