Experimental and Theoretical Investigation on Bond Behavior of Tensile Lap Spliced Basalt Fiber Reinforced Polymer Bars in High Strength Concrete Beams

Abstract

Basalt fiber reinforced polymer (BFRP) reinforcements are a possible replacement for corroding conventional steel bars. BFRP bars tension lap splices are necessary due to construction stoppages and limitations on rebar lengths. They also provide means to facilitate many forms of precast construction. Splices are used in joints to transfer forces from one reinforcing bar to the next enabling structural continuity within a member. The most widely used form of splicing is the lap splice where forces are transferred across adjacent discontinuous bars by means of the concrete in between them. The objective of this study is to investigate the factors that affect the strength of the bond behavior of the high strength concrete's tensile lap-spliced FRP basalt bars and to determine the appropriate recommendation for the high strength concrete's (HSC) lap splices of FRP basalt bars in design codes. The number of the tested beams was 11 large-scale beams which were reinforced with basalt FRP bars with two surface textures, sand-coated and helically wrapped. The beams had different splice lengths depending on the bar size. Three bar diameters were used in this study i.e. (10, 12 and 16 mm). The bars were tested to obtain their tensile strength, ultimate strain, and modulus of elasticity. The investigation of the critical splice length was done theoretically and experimentally and was compared. The theoretical part was obtained by three design codes which are: CSA-S806, CSA-S6, and ACI 440.1. The three codes were evaluated and compared to the experimental results and a conclusion was drawn. The outcomes of this study are that the prediction of the strain at the end of the splice of basalt FRP bars can be done using the ultimate strength analysis, the performance of at least one beam test leads to an appropriate prediction of the critical splice length for basalt FRP bars used for reinforcing high strength concrete beams, and the Canadian code (CSA-S806) is the best suitable code to be used in the determination of the splice length for the basalt FRP bars used to reinforce high strength concrete beams. Moreover, the bond strength decreases as the splice length increases. Additionally, the sand-coated bars showed a higher bond strength than the helically wrapped bars.