Investigation the behavior and shear ductility of RC deep beam strengthened by FRP

Document Type : Research Paper

Authors

Abstract

The demand for FRP materials has been increased over the past years for retrofitting or strengthening of reinforced concrete members. Several recent studies focused on the shear strengthening of reinforced concrete deep beams. In deep beams, due to the high ratio of shear span-to-depth and shear deformation, the ultimate strength is generally controlled by shear rather than flexure with lower shear ductility. Shear strengthening with FRP sheets is one of the most effective methods to overcome the weaknesses of deep beams.

In this paper, the behavior of 104 deep beam specimens strengthened with different schemas of FRP sheets which was investigated. Specimens were modelled through the Non Linear finite elements method and analyzed under Push over static loading.  The efficiency of FRP installing schema and the effect of some parameters such as shear span-to-depth ratio, compressive strength of concrete and the arrangement and ratio of shear reinforcement were evaluated. The results showed an average increase of shear capacity varied between 15 through 65 percent in each schemas of installed FRP sheets.

Another aim of this study is to define and evaluation of shear ductility index for deep beams. The results show that the shear ductility index depends on the dimensions of the deep beam, compressive strength of concrete and the scheme of installed FRP sheet as using the layers of FRP can increase the shear ductility of strengthened deep beams about 5 to 30 percent. 

Keywords


[1] ACI 318-14. “Building Code Requirements for Structural Concrete and Commentary”, American Concrete Institute, 2014.
[2] ACI 440.2R-08. “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures”, American Concrete Institute, 2008.
[3] A. Khalifa, G. Tumialan, A. Nanni, and A. Belarbi, “Shear Strengthening of Continuous Reinforced Concrete Beams Using Externally Bonded Carbon Fiber Reinforced Polymer Sheets”, ACI STRUCTURAL JOURNAL, SP-188, 1999, pp. 995-1008.
[4] D.I. Kachlakev, and W.A. Barnes, “Flexural and Shear Performance of Concrete Beams Strengthened with Fiber Reinforced Polymer Laminates”, ACI Journal, Vol. 188, 1999, pp. 959-972.
[5] J. Sim, G. Kim, C. Park, M. Ju, “Shear Strengthening Effects with Varying Types of FRP Materials and Strengthening Methods”, ACI STRUCTURAL JOURNAL, Vol. 230, 2005, pp. 1665-1680.
[6] Sherif H. Al-Tersawy, “Effect of fiber parameters and concrete strength on shear behavior of strengthened RC beams”, Construction and Building Material, Vol. 44, 2013, pp. 15-24.
[ 7 [ ع.ر. رهائی، " تقویت تیرهای بتن آرمه با سیستم " CFRP هشتمین کنگره بینالمللی مهندسی عمران، 1390 .
[ 8 [ ا. عربزاده، م. میرزائی، " ارزیابی مقاومت برشی تیرهای عمیق بتن مسلح ترمیم و تقویت شده با ورقهای CFRP " هشتمین کنگره
بینالمللی مهندسی عمران، 1388 .
[9] B.B. Adhikary, H. Mutsuyoshi, and M. Ashraf, “Shear Strengthening of Reinforced Concrete Beams Using Fiber-Reinforced Polymer Sheets with Bonded Anchorage”, ACI STRUCTURAL JOURNAL, Vol. 101, 2004, pp. 660-668.
[10] O. Anil, “Improving shear capacity of RC T-beams using CFRP composites subjected to cyclic load”, Cement & Concrete Composites, Vol. 28, 2006, pp.638-649
[11] Y. Kim, Kevin T. Quinn, Christopher N. Satrom, Wassim M. Ghannoum, and James O. Jirsa, “Shear Strengthening RC T-beams Using CFRP Laminates and Anchors”, ACI STRUCTURAL JOURNAL, Vol. 275, 2011, pp. 1-18.
[12] A. Godat, O. Chaallal, “Strut- and- Tie Method for externally FRP Shear Strengthened Large scale RC Beams”, Composite Structural, Vol. 99. 2013, pp. 327-338
[13] J.A.O. Barros, A.S. Fortes, “Flexural strengthening of concrete beams with CFRP laminates bonded into slits”, Cement and Concrete Composites, Vol. 27, 2005, pp. 471-480
[14] N. Attari, S. Amziane, and M. Chemrouk, “Flexural strengthening of concrete beams using CFRP, GFRP and hybrid FRP sheets” Construction and Building Material, Vol. 37, 2012, pp. 746-757
[15] A. Bournas Dionysios, and C. Triantafillou Thanasis, “Flexural Strengthening of Reinforced Concrete Columns with near surface- mounted for FRP or Stainless Steel”, ACI, Vol. 106, 2009, pp. 495-505.
[16] G.M. Dalfré, J.A.O. Barros, “NSM technique to increase the load carrying capacity of continuous RC slab”, Engineering Structures, Vol. 56, 2013, pp. 137-153.
[17] G. Foret, and O. Limam, “Experimental and numerical analysis of RC two-way slabs strengthened with NSM CFRP rods”, Const. and Build. Mat., Vol. 22, 2006, pp. 80-86.
[18] S.H. Ahmad, S. Hino, W. Chung, Y. Xie, and T. Yu, “Shear Ductility of Reinforced Concrete Beams of Normal and High Strength Concrete”, ACI STRUCTURAL JOURNAL, Vol. 91, 1994, pp. 140-149.
[19] S.W. Shin, S.K. Ghosh, and J. Moreno, “Flexural Ductility of Ultra High- Strength concrete members”, ACI STRUCTURAL JOURNAL, Vol. 86, 1989, pp. 394-400.
[20] S.W. Shin, S.K. Ghosh, and M. Kamara, “Flexural Ductility, Strength Prediction and hysteretic behavior of Ultra High- Strength concrete members”, ACI STRUCTURAL JOURNAL, SP-141, 1990, pp. 239-264
[ 21 [ ی. شریفی، ع.آ. مقصودی، "شکلپذیری اعضای خمشی بتن مسلح پر آرمه ساخته شده با مقاومت بالا"، امیرکبیر، مهندسی عمران،
شماره 2 ، 1391 ، صفحه 46 - 37