Comparison of in-situ and laboratory tests of brick masonry walls strengthened with CFRP fabric – CICE 2012

Proceedings of CICE 2012 6th International Conference on FRP Composites in Civil Engineering - Rome, Italy, 13-15 June 2012

Shear failure of masonry walls is a critical failure mechanism that in many cases leads to the sudden collapse of entire buildings during earthquakes. To improve seismic resistance of brick masonry walls the reinforcement of masonry with carbon fibre reinforced polymer (CFRP)fabric is presented as innovative and efficient strengthening technique. In order to develop the most efficient way of applying CFRP fabric to brick masonry walls, in-situ and laboratory tests were carried out and their results are compared. Laboratory tests were carried out on sixteen walls with different reinforcement configuration (diagonally strengthened, horizontally and vertically strengthened, only horizontally strengthened and un-strengthened) and six walls of different configurations were tested in-situ. Specimens were tested under constant vertical load and by displacement controlled horizontal cyclic loading. Laboratory test specimens were tested as single fixed, while in-situ specimens were tested as double-fixed. CFRP strengthening favourably influenced the mechanism of wall behaviour in all cases. It significantly increased ultimate displacement, ductility and dissipated energy. The un-reinforced masonry typically failed in diagonal shear. Diagonally reinforced masonry in laboratory failed in compression due to rocking, while horizontally reinforced specimens resisted high shear and compressive stresses and failed due to masonry compressive failure within the FRP confinement. Failure mechanism of in-situ tested specimens showed compressive failure within the FRP confinement and shear cracks. In general the behaviour of horizontally reinforced masonry exhibited much higher ductility and energy dissipation in comparison to diagonally strengthened walls.

Keywords: ductility, FRP, masonry, shear test, stiffness, strength, strengthening