Title:
Effect of FRP Wrapping Stiffness and Concrete Cover on Lap Splice Failure Behavior
Author(s):
Rayed Alyousef, Timothy Topper, and Adil Al-Mayah
Publication:
Symposium Paper
Volume:
322
Issue:
Appears on pages(s):
1.1-1.20
Keywords:
bond behavior, thickness of concrete cover, GFRP and CFRP strengthening and lap splice.
DOI:
10.14359/51706952
Date:
6/18/2018
Abstract:
Lap splices are an easy to implement low cost method of transferring force between reinforcing bars in concrete structures. However, the bond between lap spliced bars is usually the weakest region in a reinforced concrete
structure. Fiber reinforced polymer materials (FRP) are widely used to strengthen and repair lap splices because of
their high strength, durability and ease of handling. Researchers have found that increased concrete cover provides
an increase in bond strength similar to that supplied by wrapping with FRP sheets. Currently the FRP industry
produces a new generation of high stiffness FRP sheets that provide a high degree of confinement and large increases
in bond strength to lap splices.
This paper compares the effectiveness of wrapping with very high stiffness carbon FRP sheets (CFRP 900), wrapping
with low stiffness glass FRP sheets (GFRP 430) and no wrapping on the bond strength of lap splice connections for various concrete covers. The test variables were the amount of concrete cover and the wrapping condition. The results showed that the GFRP wrapped beams had an increased in bond strength of approximately 25% compared to the unwrapped beams for each of the concrete covers. However, the CFRP wrapped beams had a percentage increase in bond strength that decreased as the concrete cover increased. The CFRP wrapped beams had increases in bond strength of 71%, 60% and 44% compared to the unwrapped beams for concrete covers of 20mm, 30mm and 50 mm, respectively.
Related References:
ACI Committee 408, 2003, “Bond and development of straight reinforcing bars in tension (ACI 408-03),” American Concrete Institute, Farmington Hills, Mich., 49 pp.
ACI Committee 440, 2008, “Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures (ACI 440.2R-08),” American Concrete Institute, Farmington Hills, Mich., 76 pp.
ACI Committee 408, 2012, “Report on Bond of Steel Reinforcing Bars Under Cyclic Loads (ACI 408.2R-12),” American Concrete Institute, Farmington Hills, Mich., 39 pp.
Alyousef, R., Topper, T., and Al-Mayah, A. (2015). "Effect of FRP Wrapping on Fatigue Bond Behavior of Spliced Concrete Beams." J. Compos. Constr.,ASCE
Alyousef, R., Topper, T., and Al-Mayah, A. (2016). "Effect of the thickness of concrete cover on the fatigue bond strength of GFRP wrapped and non-wrapped reinforced concrete beams containing a lap splice." J. Structures. Elsevier,
Bousias, S., Spathis, A. L., and Fardis, M. N. (2007). “Seismic retrofitting of columns with lap spliced smooth bars through FRP or concrete jackets.” Journal of Earthquake Engineering, 11(5), 653-674.
Bournas, D. and Triantafillou, T. (2011). “Bond Strength of Lap-Spliced Bars in Concrete Confined with Composite Jackets.” J. Compos. Constr. 15, Special Issue in Honor of Professor Urs Meier, 156–167.
Canbay, E., and Frosch, R.J., (2005). “Bond Strength of Lap-Spliced Bars,” ACI Structural Journal, V. 102, No. 4, July-August, pp. 605-614.
Darwin, D.; Tholen, M. L.; Idun, E. K.; and Zuo, J., (1996a). ‘‘Splice Strength of High Relative Rib Area Reinforcing Bars,’’ ACI Structural Journal, V. 93, No. 1, Jan.-Feb., pp. 95-107.
Eligehausen, R.; Popov, E., and Bertero, V., (1983). “Local bond stress-slip relationships of deformed bars under generalized excitations,” Rep. No. UCB/EERC-83/23, Univ. of California, Berkeley.
CEB-FIP, (2000). ‘‘Bond of Reinforcement in Concrete,’’ State-of-Art Report prepared, Fédération Internationale du Béton, Lausanne, Switzerland. 434 pp.
Garcia, R.; Helal, Y.; Pilakoutas, K; and Guadagnini, M., (2014). "Bond strength of short lap splices in RC beams confined with steel stirrups or external CFRP," Materials and Structures, V.50, Jan, pp.340-351.
Hamad, B.; Rteil, A.; and Soudki, K., (2004). “Bond strength of tension lap splices in high-strength concrete beams strengthened with glass fiber reinforced polymer wraps,” J. Compos. Constr., V. 8(1), pp. 14–21.
Hamad, B. and Rteil, A., (2006). ”Comparison of Roles of FRP Sheets, Stirrups, and Steel Fibers in Confining Bond Critical Regions,” J. Compos. Constr., V.10(4), pp.330–336.
Harajli, M., Hamad, B., and Karam, K. (2002). ”Bond-slip Response of Reinforcing Bars Embedded in Plain and Fiber Concrete.” J. Mater. Civ. Eng., 14(6), 503–511.
Harajli, M. H., Hamad, B. S., and Rteil, A. A. (2004). “Effect of confinement on bond strength between steel bars and concrete.” ACI Structural Journal, 101(5), 595-603.
Harajli, M., H. (2009). “Bond strengthening of lap spliced reinforcement using external FRP jackets: An effective technique for seismic retrofit of rectangular or circular RC columns.” Construction and Building Materials, 23(3), 1265-1278.
Orangun, C.; J. Jirsa, and J. Breen., (1977). “A reevaluation of test data on development length and splices,” ACI J. Proc., V.74(3), pp.114–122.
Shihata, Ayman. (2011). “CFRP strengthening of RC beams with corroded lap spliced steel bars.” MSc. Thesis, Department of Civil and Environmental Engineering, University of Waterloo.
Soudki, K., and Sherwood, T. (2003). “Bond behavior of corroded steel reinforcement in concrete wrapped with carbon fiber reinforced polymer sheets.” J. Mater. Civ. Eng., 15(4), 358–370.
Tepfers, R., (1973). “A theory of bond applied to overlapped tensile reinforcement splices for deformed bars.” Chalmers University of Technology.