装配式风电混塔干式连接竖缝抗剪性能试验

Experimental study on shear performance of dry-type vertical seam for modular hybrid wind turbine tower

摘要:

免灌浆干式连接预应力混塔竖缝界面采用环氧树脂结构胶+弯螺栓施加预紧力共同抗剪,相比传统的灌浆湿连接+连接钢筋的形式,可以极大地提高现场安装效率。为此,针对干式连接竖缝界面的抗剪性能,以足尺试件为研究对象,开展1个直剪静力试验和两个直剪疲劳试验。研究竖缝界面在静力剪切荷载作用下的破坏模式、黏结滑移曲线及承载力计算,进一步重点分析竖缝界面的疲劳破坏模式、剪切刚度退化及疲劳寿命计算方法。试验研究和理论分析结果表明:干式连接竖缝的静力、疲劳试验均发生脆性破坏模式,界面可分为界面脱黏破坏和混凝土保护层剥离破坏两类区域,面积占比约 各50%,弯螺栓施加预紧力可以有效提高结构胶界面的黏结抗剪能力；荷载上限是影响竖缝剪切疲劳性能的关键因素,且疲劳寿命与荷载上限呈负相关；竖缝界面的抗剪能力由混凝土直接抗剪和弯螺栓预紧力产生的摩擦力共同提供,根据叠加法推导的竖缝界面受剪承载力计算公式具有较高的精度；Fib Model Code规范公式可以对竖缝的剪切疲劳寿命进行预测,预测结果具有较高的准确性和一定的安全富余,具有良好的工程应用价值。

Abstract:

The interface of dry-type vertical seam without grouting for prestressed concrete hybrid tower uses epoxy resin structural adhesive and bending bolts with pre-tension applied to resist shear. Compared with the traditional grouted wet connection with connecting steel bars, this approach can greatly improve on-site installation efficiency. Aiming at the shear performance of the vertical seam interface of dry-type connection, one direct shear static test and two direct shear fatigue tests were carried out on full-scale specimens. The failure mode, bond-slip curves, and bearing capacity calculation of the vertical seam interface under static shear loading were systematically investigated. Furthermore, the fatigue failure mode, degradation of shear stiffness, and methods for fatigue life prediction of the seam interface were further analyzed. The results of experimental research and theoretical analysis show that both static and fatigue tests of the dry-type vertical seams have brittle failure modes. The interface failures can be divided into two regions: interface debonding and delamination of the concrete protective layer—each occupying roughly 50% of the damaged area. The pre-tension applied by the bending bolts can effectively improve the shear capacity of the structural adhesive interface. The upper limit of load is the key factor affecting the shear fatigue performance of vertical seams, and the fatigue life is negatively correlated with the upper limit of load. The shear capacity of the vertical seam interface is provided jointly by the friction force generated by the direct shear of concrete and the pre-tension of the bending bolts. The calculation formula of the shear capacity of the vertical seam interface deduced by the superposition method shows high accuracy. The Fib Model Code specification formula is capable of predicting the shear fatigue life of vertical seams with commendable accuracy and a built-in safety margin, rendering it highly valuable for engineering applications.