Hybrid flexural components: Testing pre-stressed steel and GFRP bars together as reinforcement for flexural members

Abstract

Concrete members historically have used either pre-stressed steel or steel bars. In recent years there has been an increased interest in the use of fiber reinforced polymer (FRP) materials. However, the flexure behavior of a hybrid system reinforced by the combination of pre-stressed steel and glass fiber reinforced (GFRP) is still relatively unknown. The purpose of this work is to study this. Two slabs of 100 and 150-millimeter thickness, with a span of 2.1 m reinforced with both pre-stressing steel and GFRP were constructed and tested to failure using ACI 318-11 and ACI 440.1R-15. The concrete had strength of 31 MPa and the slabs were respectively reinforced with 5#4 bars and 3#5 bars. Each slab had 37.41 mm² prestressing wire with a failure stress of 1722.5 MPa. The experimental flexural strength and deflection of slabs were compared with their respective sizes theoretical slabs. The theoretical slabs were either reinforced with pre-stressed steel or GFRP rebars, or a hybrid system. It was found that the hybrid system produces better results.

Keywords

Partial pre-stressing / composite structures / GFRP bars

References

[1] Nanni A, De Luca A, Zadeh J H. Introduction. In: Reinforced Concrete with FRP Bars. Florida: CRC Press-Taylor & Francis Group, 2014

[2] Guide for the Design and Construction of Structural Concrete Reinforced with Fiber-Reinforced Polymer (FRP) Bars. ACI 440.1R-15, 2015

[3] Nilson H A. Design of Prestressed Concrete. 2nd ed. Canada: John Wiley & Sons, Inc, 1987, 103

[4] Singh B S. Design of RC Structures Reinforced with FRP Bars. In: Analysis and Design of FRP Reinforced Concrete Structures. New Delhi: McGraw-Hill, 2015, 67–78

[5] Building Code Requirements for Structural Concrete. ACI 318-11, 2011

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