Introducing textile reinforced concrete for retrofitting of existing structures : numerical design prediction

The structural engineering had faced recently a quite new engineering challenge due to the necessity to figure out the optimum solution in strengthening old buildings which had experienced damage due to the failure of its structural members to stand with the acting stresses. In that sense, many strengthening techniques had been developed such as; the so called traditional techniques (RC or steel jacketing) and using of advanced cementitious composites like Fibre reinforced concrete and Textile reinforced concrete. The common problems linked to traditional techniques are mainly; the excessive increase of the element section and mass due to the added RC jacketing which reaches to 60-70 mm, while the low fire resistance of the glued steel jacketing is considered a negative aspect when steel jacketing is used. Textile reinforced concrete was introduced as a strengthening material and it has been characterized with its excellent mechanical properties especially the pronounced pseudo-ductile behavior and tensile strength. TRC is produced by combining a very fine grained concrete with multiaxial fabric. Furthermore, adding Alkali resistant (AR) glass, Carbon, Kevlar or Aramid to the TRC matrices gives high effectiveness because they are placed in the main stresses directions. Unlike the randomly distributed short fibres such as glass fibre reinforced concrete (GRC), the advantage of al-kali-resistant (AR) glass or carbon fibres in comparison with steel reinforcements is that they are not prone to corrosion. So no need to add a concrete cover sequentially slimmer element can be obtained. The parameters that feature the behavior of TRC are multiple. Particularly, the fabric geometry, the method that the fibres were woven and the contact surface between the added layer of TRC and the old existing element is triggering the performance of the strengthened element. In this sense, the surface treatment determines transmission of the tangential stresses through the contact surface. This research aims to study the mechanical characterization of textile reinforced concrete by experimental investigations carried out on different TRC matrices mix design and the effect of adding the polypropylene fibres to the TRC. Moreover, a comprehensive explanation to the coupling behavior of reinforced concrete specimen retrofitted by textile reinforced concrete is explained in this thesis as well by presenting double edge wedge splitting test in two approaches; experimental and numerical. The numerical approach used the finite element software Abaqus for modeling un-retrofitted and retrofitted specimens with TRC in order to study the correspondence between the experimental and numerical approaches results. Furthermore, studying the effect of adding polypropylene to TRC was highlighted as well.