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Torsional Strengthening of Damaged Low-strength RC Beams Using Prestressed Ductile Metal Straps

Katipoj Sanupong, Weerasit Chamnankit, Komsan Dangyem, Thanongsak Imjai


งานวิจัยนี้ศึกษาประสิทธิภาพของระบบเสริมกำลังโดยวิธีการโอบรัดด้วยเหล็กแผ่นบางโอบรัดภายหลัง โดยวัตถุประสงค์เพื่อทำการศึกษาประสิทธิภาพของการเสริมกำลังคานคอนกรีตกำลังอัดต่ำภายใต้แรงบิด โดยทดสอบในระยะที่ 1 ทำการทดสอบเพียงแค่รอยร้าวแรกเท่านั้น เพื่อจะศึกษาว่าแผ่นเหล็กเหนียวสามารถเพิ่มกำลังในการรับแรงบิดได้อย่างมีนัยสำคัญ และในระยะที่ 2 ทำการเสริมกำลังคานคอนกรีตกำลังอัดต่ำภายหลังจากที่เกิดรอยร้าวแล้วจากในระยะที่ 1 เพื่อจำลองสถานการณ์ที่อาคารได้รับความเสียหาย ภายใต้แรงบิดในห้องทดลอง ผลจากการศึกษาพบว่า วิธีการเสริมกำลังคานคอนกรีตด้วยวิธีแผ่นเหล็กเหนียวอัดแรงภายหลัง มีผลต่อการเพิ่มความสามารถในการรับแรงบิด สูงสุดร้อยละ 33 เมื่อเปรียบเทียบกับการซ่อมแซมคานคอนกรีตกำลังอัดต่ำโดยปูนซีเมนต์แบบไม่หดตัวชนิดพิเศษที่มีกำลังอัดสูง (Non-Shrink grout) ซึ่งมีผลต่อการเพิ่มขึ้นของกำลังรับแรงบิดประลัยเพียงเล็กน้อย

This research deals with the efficiency of torsional strengthening system on damaged low-strength reinforced concrete (RC) beams using post-tensioned metal strapping (PTMS) technique on 2-phase experiment. In phase 1, the test focused only on the first crack to determine the significant increase of torsional strength. In phase 2, all pre-cracked beam specimens from phase 1 were repaired with non-shrink cement and confined with high-ductile metal straps. To simulate the damage building, all strengthening beams were subsequently re-tested under pure torsion in the laboratory. Based on the test results, it is found that the use of the PTMS technique significantly enhances the torsional capacity. It is also found that the use of non-shrink cement as a crack repairing material for damaged concrete beams increased only the ultimate torsion capacity of the strengthening beams by up to 33%.


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DOI: 10.14416/j.kmutnb.2022.07.008

ISSN: 2985-2145