Investigation of the Effects of CFRP on Load Bearing Capacity of Strengthened Two-Way RC Squared Slabs with Side and Corner Openings

مهندسی عمران فردوسی

Article 7, Volume 29, Issue 1 - Serial Number 18, July 2017, Pages 93-108   

Document Type: Research Note

DOI: 10.22067/civil.v29i1.21662

Author

mojtaba labibzadeh^*

Shahid Chamran University of Ahvaz

Abstract

Due to existence of the facility ducts, such as elevators, heating, and cooling systems in buildings, creating of the openings in the reinforced concrete slabs is inevitable. Usually, small openings have negligible effects on the slab performance whereas the large openings can affect significantly on the slab behavior and can cause the stress concentration adjacent to the openings. In some cases, ignoring this issue can cause serious problems in the integrity, stiffness and even stability of structures. One of the rehabilitation and strengthening methods of such slabs is the use of Fiber Reinforce Polymers sheets (FRPs). In this research, the influence of the lateral and corner openings as well as the impact of using a kind of FRPs known as CFRP (Carbon Fiber Reinforce Polymer sheets) for strengthening of two-way slabs were investigated. The obtained results indicate that this method can be successfully employed in remedy operations for mentioned slabs. CFRP sheets can recover the lost flexural rigidity of the slab considerably and even in some cases can improve it in comparison to that of homogeneous slab (slab with no opening). The results also show that by implementing this method the flexural rigidity of the slab can be increased between 12 to 30 percent in the case of slabs with lateral opening and between 1 to 10 percent in the case of slabs with the corner opening relative to the original weakened slab (slab with opening without strengthening).

Keywords

Two-Way RC Squared Slabs; CFRP; Load Bearing Capacity; Side and Corner Openings

References

1. Erhard, G. "Designing with Plastics", Hanser Gardner Publication, Inc., (2006).

2. Arduini, M., D'Amrisi, A., and Tommaso, A. D. "Shear failure of concrete beams reinforced with FRP plates", In proceedings, infrastructures: A new materials and methods of repair, proceedings of the third materials engineering conference, San Diago, CA, USA, pp. 123-130, (1991).

3. GangaRao, H. V. S. and Vijay, P. V. "Bending behavior of concrete beams wrapped with carbon fabric", Journal of structural engineering, Vol. 124(1), pp. 3-10, (1998).

4. Triantafillou, T. C. "Shear strengthening of reinforced concrete beams using epoxy-bonded FRP composites", ACI Structural Journal, Vol. 95(2), pp.107-115, (1998).

5. Nitereka, C. and Neale, K. "Analysis of reinforced concrete beams strengthened in flexure with composite laminates", Canadian journal for civil engineering, Vol. 26, pp. 646-654, (1999).

6. Julio, F. D., and Pizhong, Q. "A computational approach for analysis and optimal design of FRP beams", Computers and Structures, Vol. 70(2), pp. 169-183, (1999).

7. Wu, Y., Zhu, Y., Lai, Y., and Pan, W., "Analysis of shear lags and shear deformation effects in laminated composite box beams under bending loads", Composite Structures, Vol. 55(2), pp. 147-156, (2002).

8. Zheng, Z., and Taheri, F., "Numerical studies on dynamic pulse buckling of FRP composite laminated beams subject to an axial impact", Composite Structures, Vol. 56(3), pp. 269-277, (2002).

9. Håkan, N., and Täljsten, B., "Testing of hybrid FRP composite beams in bending", Composites Part B: Engineering, Vol. 35(1), pp. 27-33, (2004).

10. Wegian, F. M., and Abdalla, H. A. "Shear capacity of concrete beams reinforced with fiber reinforced polymers", Composite Structures, Vol. 71(1), pp. 130-138, (2005).

11. Jae, H. L., Lopez, M., and C., Bakis, Bakis, "Slip effects in reinforced concrete beams with mechanically fastened FRP strip", Cement and Concrete Composites, Vol. 31(7), pp. 496-504, (2009).

12. Naghipour, M., Nematzadeh, M., and Yahyazadeh, Q., "Analytical and experimental study on flexural performance of WPC–FRP beams", Construction and Building Materials, Vol. 25(2), pp. 829-837, (2011).

13. Ebead, U., Marzouk, H. and Lye. M., "Strengthening of two-way slabs using FRP materials: a simplified analysis based on response surface methodology", 2nd World Engineering Congress, Sarawak, Malaysia, 22-25 July, (2002).

14. Ebead, U., and Marzouk. H., "Tension-stiffening model for FRP-strengthened RC concrete two-way slabs", Materials and Structures, Vol. 38, pp. 193-200, (2004).

15. Mosallam, A. S., and Mosalam, K. M., "Strengthening of two-way concrete slabs with FRP composite laminates", Construction and building materials, Vol. 17, pp. 43-54, (2003).

16. El-sayed, W. E., Ebead, U. A., and Neale, K. W., "Mechanically Fastened FRP-Strengthened Two-Way Concrete Slabs with and without Cutouts", Journal of Composites for Construction, ASCE, Vol. 13(3), pp. 198-207, (2009).

17. Lubliner, J., Oliver, J., Oller, S. and On˜ate, E. "A plastic-damage model for concrete", International Journal of Solids and Structures, Vol. 25(3), pp. 229–326, (1989).

18. Enochsson, O., Lundqvist, J., Ta¨ljsten, B., Rusinowski, P. and Olofsson, T., "CFRP strengthened openings in two-way concrete slabs –An experimental and numerical study", Construction and Building Materials, Vol. 21, pp. 810-826, (2007).