This paper investigate the efficiency of using post-tension stainless steel links and steel links systems for strengthening and repairing R.C beams without and with web opening subjected to pure torsion. Post-tension force was produced in vertical links ofhigh strength material using steel plate at top and bottom surface of the beams anchored with fine threads. Twenty Two specimens are divided into two parts, one part deal with solid beams and other deal with beams with web opening. The effect of post-tension force in vertical links, spacing between vertical links, post-tension technique (links –U shape), plates configuration and opening length are the effective variables on the torsion capacity were studied in this research. The experimental results showsthat the post-tension system is very effective strengthening and repairing method to enhance torsion beam capacity up to 27.55 %. This system also increase the beams ductility, delay the appearance of first crack and reduce the crack width within increasing in applied torque till failure. Torsion capacity of beams with web opening strengthened with post-tension system significantly improves over the control beams and in some case reach the capacity of solid control beam. Failure of beams strengthened with post-tension system was due to spalling of concrete cover due to torsional moment. The failure of beams with web opening strengthening with post-tension system was in solid part not in opening corner as control beams with web opening. |
