桥梁单锥孔夹片式预应力锚具握裹力分析

反拉法以测试曲线的拐点来判断锚下有效预应力,是当前最为广泛的锚下有效预应力检测手段。近年,众多学者发现测试曲线拐点处存在荷载骤降的情况。因此,针对反拉法测试曲线的突变段成因进行了探讨,提出了反拉荷载在夹片拉脱过程中需克服锚具握裹力从而导致突变段产生的观点。其中,锚具握裹力主要由锚圈与夹片的摩阻力和锚圈与夹片的机械咬合力构成。同时,为了得到握裹力的影响因素,建立了单锥孔夹片式锚具握裹力分析的有限元模型,设计并阐述了有限元模型的握裹力提取方法。通过有限元模型得到了影响锚具握裹力的3项影响因素——控制张拉力、摩擦系数、锥孔数量,并拟合了控制张拉力、摩擦系数与握裹力的关系曲线,得出了控制张拉力、摩擦系数与握裹力正相关的结论。

Analysis on Gripping Force of Single-cone-hole Wedge-type Prestressed Anchorage for Bridges

The reverse-pull-method is currently the most widely used method for detecting the effective prestress under the anchor. It uses the inflection point of the test curve to determine the effective prestress under the anchor. In recent years, many scholars have found that there is a sudden load drop at the inflection point of the test curve. Therefore, this paper discusses the causes of the sudden change in the test curve of the reverse-pull-method, and proposes that the reverse pull load needs to overcome the anchorage grip force during the clip pulling process, which leads to the generation of the sudden change segment. The anchor grip force is the main It is composed of the friction resistance of the anchor ring and the clip and the mechanical bite force of the anchor ring and the clip; at the same time, in order to obtain the influencing factors of the gripping force. A finite element model for the analysis of the gripping force of the single-cone-hole clip-type anchorage is established, and the method for extracting the gripping force of the finite element model is designed and described. Through the finite element model, three factors affecting the anchorage''s grip are obtained: control tension, friction coefficient, and the number of taper holes. The relationship between the control tension force, friction coefficient and grip force was fitted, and the conclusion was drawn that the control tension force, friction coefficient and grip force were positively correlated.