Advances in retrofit of concrete bridges by a new wedge anchorage for prestressing of CFRP-elements

摘要

The anchor types found in literature can be categorized as cast anchors with resin or grout, anchors with expansive material, spike anchors, wedge anchors, other clamping mechanisms and various combinations. The anchorage system for CFRP-strips described in this paper, called the Composite Wedge System, is composed of an anchor body and two or a single Composite Wedge (Burtscher 2004) for each strip. These wedges are made of two components with different modulus of elasticity and varying thickness. Due to this special design the transversal pressure and the shear stresses are evenly distributed along the wedge - CFRP strip interface. This enables the system to anchor very high loads. When the CFRP-strip needs to be anchored close to the surface of a structure the asymmetric anchorage system is a special design. A short distance to the structure surface reduces the strength requirement for bonding and bolting of the anchor plates. This is beneficial in various applications, for example, in strengthening of bridges. For CFRP-rods the same principle applies, but here at least two wedges per rod are necessary.