STRESS TRANSFER IN THE BOND JOINT OF SUBSEQUENTLY APPLIED TEXTILE REINFORCED CONCRETE STRENGTHENING

摘要

The application of textile reinforced composites made of endless high-performance reinforcement material and concrete permits the manufacturing of very thin layers for the service and strengthening of existing building structures. One of the special topics which arises by using the material is the question of the ultimate load introduction force from the old concrete into the textile reinforced concrete strengthening layer. Some special problems occur when using textile reinforced layers compared to other strengthening systems such as adhesive bonded steel plates or FRP-lamellas. Using the test results obtained, the behaviour of textile reinforced fine grained concrete strengthening layers for RC members within the anchoring range is being discussed and a modelling approach is given. Different possible failure modes of the bonding system are presented. The failure mode delamination is presented in more depth. Thereby the effect of the adhesive tensile strength on the required bond length is shown for two different textiles. Several special properties of the textile reinforced fine grained concrete strengthening layer are explained in detail, e. g. the crack formation within the strengthening layer, and they are compared with strengthening layers made of steel or CFRP. The resulting properties of the bond between the old concrete and the strengthening layer are derived. Hence it is shown that it becomes necessary to extend existing models accordingly.