Title:
ESTABLISHING THE SHEAR CONSTITUTIVE LAWS OF FRP-STRENGTHENED RC MEMBERS
Author(s):
Mehdi Zomorodian and Abdeldjelil Belarbi
Publication:
Symposium Paper
Volume:
328
Issue:
Appears on pages(s):
13.1-13.22
Keywords:
Constitutive modeling; FRP strengthened RC members; Shear behavior; truss model
DOI:
10.14359/51711157
Date:
9/12/2018
Abstract:
The behavior of FRP strengthened RC members has not been fully clarified due to lack of accurate constitutive laws for the components of the members. This paper presents experimental and analytical investigations of parameters that affect the various material laws of FRP strengthened RC elements. The material laws of concrete in tension, steel in tension, FRP in tension, softening coefficient, and modified Hsu/Zhu ratios were further developed in this research. To study the behavior and the main affecting parameters of FRP strengthened RC members subjected to shear, experimental tests of panels subjected to pure shear stress fields were conducted. The main variables investigated are steel reinforcement ratio, FRP reinforcement ratio and wrapping schemes of FRP sheets. The results show that the tensile behavior of the concrete and steel is altered because of the externally bonded FRP sheets. Also, the softening coefficient and the Hsu-Zhu ratios for FRP-strengthened RC vary greatly compared to RC elements without FRP reinforcement. Modified constitutive laws are proposed and incorporated in the Softened Membrane Model (SMM) to demonstrate the behavior of FRP-strengthened RC element subjected to pure shear. The newly developed analytical model is referred to as the Softened Membrane Model for FRP strengthened RC members (SMM-FRP).
Related References:
ACI Committee 440. (2017). Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures (ACI 440.2R-178). Farmington Hills, MI: American Concrete Institute.
Bakis, C. E., Bank, L. C., Brown, V. L., Cosenza, E., Davalos, J. F., Lesko, J. J., Machida, A., Rizkalla, S. H., and Triantafillou, T. C., (2002). Fiber-reinforced polymer composites for construction: State-of-the-art review. Journal of Composites for Construction, 6(2), 73-87.
Belarbi, A., and Hsu, T. T. C., (1995). Constitutive laws of softened concrete in biaxial tension compression. ACI Structural Journal, 92(5), 562-573.
Belarbi, A., and Hsu, T. T. C., (1994). Constitutive laws of concrete in tension and reinforcing bars stiffened by concrete. ACI Structural Journal, 91(4), 465–474.
Belarbi, A., Bae, S. W., Ayoub, A., Kuchma, D., Mirmiran, A., and Okeil, A., (2011). NCHRP Report 678: Design of FRP systems for strengthening concrete girders in shear. Washinton, DC: National Cooperative Highway Research Program.
Bousselham A., and Chaallal O., (2008). Mechanisms of shear resistance of concrete beams strengthened in shear with externally bonded FRP. Journal of Composite for Constructions, 12(5), 499-512.
Cao, S. Y., Chen, J. F., Teng, J. G., Hao, Z., and Chen, J., (2005). Debonding in RC beams strengthened with complete FRP wraps. Journal of Composites for Construction, 9(5), 417-428.
Chaallal, O., Shahawy, M., and Hassan, M., (2002). Performance of reinforced concrete T-girders strengthened in shear with carbon fiber reinforced polymer fabrics. ACI Structural Journal, 99(3), 335-343.
Chen G. M., Teng J. G., and Chen J. F., (2010). Interaction between steel stirrups and shear-strengthening FRP strips in RC Beams. Journal of Composite for Constructions, 14(5), 498-509.
Chen, G., Teng, J., and Chen, J., (2013). Shear strength model for FRP-strengthened RC beams with adverse FRP-steel interaction. Journal of Composites for Construction, 17(1), 50-66.
Chen, J. F., and Teng, J. G., (2003). Shear capacity of Fiber-Reinforced Polymer-strengthened reinforced concrete beams: Fiber Reinforced Polymer rupture. Journal of Structural Engineering, 129(5), 615-625.
Deniaud, C., and Cheng, J. J. R., (2004). Simplified shear design method for concrete beams strengthened with fiber reinforced polymer sheets. Journal of Composites for Construction, 8(5), 425-433.
Dussek, I., (1987). NCHRP Report 785: Strengthening of bridge beams and similar structures by means of epoxy-resin-bonded external reinforcement. Washington, DC: National Cooperative Highway Research Program.
Hsu T. T. C., Belarbi A., and Pang X. (1995). A universal panel tester. Journal of Testing and Evaluation, 23(1), 41-49.
Hsu, C. T. T., Punurai, W., and Zhang, Z., (2003). Flexural and shear strengthening of RC beams using Carbon Fiber Reinforced Polymer laminate, ACI SP 211-5, 89-113.
Khalifa, A., Gold, W., Nanni, A., & Abdel Aziz, M. I. (1998). Contribution of externally bonded FRP to shear capacity of RC flexural members. Journal of Composites for Construction, 2(4), 195-202.
Klaiber, F.W., Dunker, K.F., Wipf, T.J., and Sanders, W.W., (1987). NCHRP Report 293: Methods of strengthening existing highway bridges. Washington, DC: National Cooperative Highway Research Program.
McKenna, F. and Fenves, G. L. (2002). The OpenSees command language primer. University of California, Berkeley, CA.
Monti, G., and Liotta, M. A,. (2005). FRP-strengthening in shear: tests and design equations. Proceedings of 7th International RILEM Symposium on Non-Metallic (FRP) Reinforcement for Concrete Structures (FRPRCS-7). Kansas City, Missouri
Moslehy, Y., (2010). Constitutive relationships and smart aggregates-based damage evaluation of FRP retrofitted concrete membrane elements (Doctoral dissertation). Department of Civil and Environmental Engineering, University of Houston, Houston, Texas
Teng, J. G., Lam, L., and Chen J. F., (2004). Shear strengthening of RC beams with FRP composites. Progress in Structural Engineering and Materials, 6(1), 173-184.
Triantafillou, T. C. (1998). Shear strengthening of reinforced concrete beams using epoxy-bonded FRP composites. ACI Structural Journal, 95(2), 107-115.
Yang G, Zomorodian M, Belarbi A, and Acun B., (2014). Tension stiffening of reinforced concrete shear elements strengthened with externally bonded FRP sheets. In: 37th IABSE Symposium Madrid. Madrid (Spain). p. 145–52.
Zhu, R. R. H., and Hsu, T. T. C., (2002). Poisson effect in reinforced concrete membrane elements. ACI Structural Journal, 99(5), 631–640.
Vecchio, F. J., and Collins, M. P., (1986). The Modified Compression-Field Theory for reinforced concrete elements subjected to shear. ACI Structural Journal, 83(2), 219-231.