Experimental study on shear mechanism of CFRP strengthened RC Beams without Stirrups under impact loading
HUO Jingsi1,2, LIU Jintong1, ZHAO Lingyu1,XIAO Yan3
1. China Ministry of Education Key Laboratory of Building Safety and Energy Efficiency, Hunan University, Changsha 410082, China；
2. College of Civil Engineering, Huaqiao University, Xiamen 361021, China；
3. College of Civil Engineering, Nanjing Tech University, Nanjing 210009
Abstract：In order to further understand the impact behavior of reinforced concrete beams strengthend with externally bonded FRP sheet, one RC beam without stirrups and two FRP strengthened RC beams without stirrups were tested against impact loads and one FRP strengthened beam was tested under static load. Test results showed that the impact resistance of FRP strengthened RC beams significantly increased, especially when the beams was strengthened with end anchorage. The failure modes and time-histories of impact force, mid-span displacement, strain of longitudinal reinforcement were analyzed and discussed, the shear mechanism of CFRP strengthened RC beams without stirrups under impact loading was obtained. The failure process can be divided into two stages, the shear failure of local part of the beams adjacent to the mid-span section under impact loading and the subsequent shear failure of near-support section under reaction force. The FRP contribution to shear strength at the two stages was discussed respectively and compared with the predicted shear strength according to different design codes. The comparisons showed that, FRP contribution to shear strength under impact loading at both stages was higher than predicted shear strength. Compared with the previous method to predict the bond strength of CFRP-to-concrete interface under impact loading, it could offer reliable reference to reasonably evaluate the contribution of FRP to shear strength.
霍静思1,2，刘进通1，赵灵雨1，肖岩3. 冲击荷载下CFRP加固无腹筋梁的抗剪失效机理试验研究[J]. 振动与冲击, 2017, 36(15): 187-193.
HUO Jingsi1,2, LIU Jintong1, ZHAO Lingyu1,XIAO Yan3. Experimental study on shear mechanism of CFRP strengthened RC Beams without Stirrups under impact loading. JOURNAL OF VIBRATION AND SHOCK, 2017, 36(15): 187-193.
[1] Fu H C, Erki M A, Seckin M. Review of Effects of Loading Rate on Concrete in Compression[J]. Journal of Structural Engineering, 1991, 117(12): 3645-3659.
[2] Malvar L J, Ross C A. Review of strain rate effects for concrete in tension[J]. ACI MATERIALS JOURNAL, 1998 ,95(6): 735-739.
[3] Banthia N P. Impact Resistance of Concrete[D]. Vancouver, Canada: Univ. of British Columbia, 1987
[4] Kishi N, Mikami H, Matsuoka K G, Ando T. Impact Behavior of Shear-Failure-Type RC Beams without Shear Rebar[J]. International Journal of Impact Engineering, 2002, 27: 955-968.
[5] Saatci S, Vecchio F J.Effects of Shear Mechanisms on Impact Behavior of Reinforced Concrete Beams[J]. ACI Structural Journal, 2009,106(1): 78-86.
[6] Bhatti A Q, Kishi N, Mikami H, Ando T. Elasto-plastic impact response analysis of shear-failure-type RC beams with shear rebars[J]. Materials and Design,2009,30: 502-510.
[7] ACI 440.2R-08. Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures[S]. American Concrete Institute, 2008
[8] Committee Concrete Society. Design guidance for strengthening concrete structures using fiber composite materials[S]. in: Technical Report No. 55, Century House, Telford Avenue, Crowthome, Berkshire RG45 6YS, UK, 2000
[9] JSCE, Recommendations for upgrading of concrete structures with use of continuous fiber sheets[S]. 2000
[10] Fib. Externally bonded FRP reinforcement for RC structures[S]. Bulletin, 2001
[11] Chen J F, Teng J G. Shear capacity of FRP-strengthened RC beams: FRP debonding[J]. Construction and Building Materials, 2003, 17: 27–41.
[12] Erik M A, Meier U. Impact Loading of Concrete Beams Externally Strengthened with CFRP Laminates[J]. Journal of Composites for Construction, 1999, 3(3): 117-125.
[13] White T, Soudki K, Erki M. Response of RC Beams Strengthened with CFRP Laminates and Subjected to a High Rate of Loading[J]. Journal of Composites for Construction, 2001, 5(3): 153-162.
[14] Tang T, Saadatmanesh H. Behavior of Concrete Beams Strengthened with Fiber-Reinforced Polymer Laminates under Impact Loading[J]. Journal of Composites for Construction, 2003, 7(3): 209-218.
[15] 许斌，曾翔. 冲击荷载下钢筋混凝土深梁动力性能试验研究[J]. 振动与冲击，2015,34(4)：6-13.
XU Bin, ZENG Xiang. Tests for dynamic behaviors of deep RC beams under impact loadings[J]. Journal of vibration and shock, 2015, 34(4):6-13.
[16] GB50010-2010 混凝土结构设计规范[S]. 北京：中国建筑工业出版社，2010
[17] Comite Euro-International du Beton. CEB-FIP model code [S]. Trowbridge, Wiltshire, UK: Redwood Books, 1990
[18] Huo J S, Liu J Y, Dai X Q, Yang J. Experimental study on dynamic behavior of CFRP-to-concrete interface[J]. Journal of Composites for Construction, 2016, 04016026.
[19] 史巨元. 钢的动态力学性能及应用[M]. 北京：冶金工业出版社，1993
