Bond-slip Behavior Of BFRP Bars In Concrete Under Cyclic Loading

This study aimed to explore the monotonic and cyclic bond behaviour of basalt fibre reinforced polymers(BFRP)bars.A series of standard pull out tests was conducted in order to examine the monotonic bond behaviour of BFRP bars with 4 different surface treatment(smooth,wounded,wrapped,and sand-coated)compared to deformed steel bars.The investigated parameters included the bar diameter,the concrete compressive strength,in addition to the surface treatment the bar.The results showed the significant effect of the surface treatment on the monotonic bond behaviour of BFRP bars and superiority of wounded BFRP bars' bond performance compared to all other studied bars.Afterwards,cyclic pull out tests were conducted with the purpose of discovering the bond behaviour of BFRP under cyclic loading.6 different cyclic loading protocols with various characteristics were applied and ended with a monotonic loading to examine the residual bond stress of BFRP bars.The effect of the surface treatment of BFRP bars,bar diameter,concrete compressive strength,number of loading-unloading cycles,cyclic loading amplitude,and cyclic loading direction(tension-tension and tension-compression)on the bond behaviour of BFRP bars was examined and compared to that of steel bars.All tested bars exhibited a deterioration in the bond-slip behaviour ranged from slight to significant deterioration based on the bar surface treatment and loading conditions.Once more wounded BFRP bars showed a better ability to resist cyclic loading with less impact on the bond behaviour compared to other bar types.The number of the applied cycles affected the cyclic bond behaviour more than other parameters.Based on the experimental results a numerical model was proposed to predict the cyclic bond behaviour of wounded BFRP bars.The accuracy and reliability of the proposed model were assessed against the experimental results.