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. Ferro cement 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 Ferro cement (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.

An experimental investigation of the STRENGTHening of the TORSIONAL resistance of High-STRENGTH Concrete (HSC) beams using Carbon-Fiber-Reinforced-Polymers (CFRP) is conducted. A total of seven beams are tested. Three beams are designated as reference specimens and four beams are STRENGTHened using CFRP wrapping of different configuration and then tested. The variables considered in the experimental study include different wrap configurations such as: U-wrapping, full and strip wrapping, the effect of the number of CFRP plies and the influence of anchors in U-wrapped test beams. The reference and the STRENGTHened beams are subjected to pure TORSIONAL moment. The load, the twist angle of the beams and the strains at longitudinal, transverse re-bars and CFRP are recorded to failure. In the current study, the ductility ratios and their increased percentage are investigated using two rather different methods. In further study, increasing the cracking, yield and ultimate TORSIONAL capacity of the STRENGTHened beams is evaluated. Finally, experimental results are compared to several analytical results. The ultimate TORSIONAL STRENGTHs that are obtained by one of the analytical methods are in good agreement with the experimental results.

The purpose of this study is first to determine the conditions for excessive TORSIONAL irregularity and then to discuss the validity of code provisions. A parametric investigation is performed on six groups of typical structures with varying shear wall positions, story, and axis numbers. It is found that TORSIONAL irregularity coefficients increase as the story numbers decrease, i.e., maximum irregularity coefficients occur for single-story structures. They reach maximum values when the asymmetrical shear walls are placed as close as possible to the centers of mass. However, the results obtained for floor rotations are quite contradictory. A new provisional definition for TORSIONAL irregularity coefficient based on floor rotations is proposed.

This paper expresses the effects of silica fume, super plasticizer and GFRP on the TORSIONAL STRENGTH of self-compacting concrete (SCC) beams. SCC and control concrete mix designs in this study are based on 20 different mixes with the water-cement ratios of 0.35 and 0.45. For Torsion tests, beams with the dimensions of 40 × 10 × 10 cm were casted. To determine the compressive STRENGTH and Pundit tests, Cubic specimens with the dimensions of 10 × 10 × 10 cm and standard cylindrical specimens with the dimensions of 15 × 30 cm height were made and cured for 28 days before testing. The obtained experimental results show that the effect of silica fume in w/c=0.45 was more than the other on TORSIONAL capacity was. The TORSIONAL STRENGTH of concrete beams with GFRP was increased about 43%. The error of estimating the compressive STRENGTH of concrete by pundit test was 2%. In addition, the existing equations for estimating the TORSIONAL STRENGTH of ordinary concrete can be used for Self Compacting concrete.