Seismic Assessment of RC Joints Retrofitted on the Web by FRP Composites

Recently, fibre-reinforced plastic (FRP) composites are widely used to strengthen various parts of a structure. Joints are important parts of structures which their failure is detrimental to the overall stability of the structure during an earthquake. An investigation on the performance of a joint from a moment resisting reinforced concrete eight-storey frame was carried out by using ABAQUS finite element software. Composites were applied on the web of the joint with different thicknesses. Proper constitutive models were used to simulate the behaviour of concrete, steel and FRP composites in the finite element program. After analysis, good agreement between finite element and experimental results was observed. Results show that this retrofitting technique, which is based on the weak beam-strong column principle, not only can increase the maximum load, displacement and moment-carrying capacity of the joint but also relocates the formation of plastic hinges in the beam further away from the column. In addition, the first steel yielding occurs at higher loads and is shifted into the cut-off point of FRP composites. However, ductility of the joint due to the web strengthening technique is reduced. Different values of fracture energy of concrete are also chosen to study the influences of this factor on the tension softening behaviour of concrete. It was observed that when fracture energy increased, load-displacement carrying capacity also increased specially at initial displacements.

کلیدواژه ها:

Reinforced Concrete Joint ، Strengthening ، Fiber-reinforced Plastics ، ABAQUS