Torsional Capacity of High Strength Concretebeams Jacketted with Ferrocement U-Wraps

Jacketing with composites on the outer periphery is one of an effective way to enhance the torsional capacity of distressed reinforced concrete structures and to change the mode of failure from brittle to ductile. Ferrocement due to its better crack arresting capacity and better strain distribution across the section make it one of the suitable composite materials in the field of strengthening reinforced concrete members. An experimental programme consisting of casting and testing of beams with “U” wraps (more commonly used strengthening technique) was conducted in the laboratory to study the effect of aspect ratio (ratio of depth to breadth), constituent materials of ferrocement (viz., number of mesh layers, yield strength of mesh layers and compressive strength of mortar) and concrete strength on ultimate torsional strength and twist. This experimental results briefly recounts that wrapping on three sides enhance the ultimate torque and twist. This strengthening scheme is more effective for higher aspect ratios with high strength jacketing material. An analytical model proposed in this paper for prediction of torque and twist response of jacketed beams is in good agreement with experimental results.