Flexural capacity of concrete beams reinforced by different types of polypropylene fibers and FRP bars

The application of basalt fiber reinforced polymer (BFRP) and carbon fiber reinforced polymer (CFRP) reinforcements offers benefits such as high strength, excellent corrosion resistance, and eco-friendliness, making it a focal point in architectural advancements. The integration of polypropylene fiber (PPF) enhances the crack resistance of reinforced concrete (RC) beams and fiber-reinforced polymer reinforced concrete (FRPRC) beams, effectively mitigating the challenges associated with large quantities and widths of cracks in FRPRC beams. However, the performance characteristics, crack resistance, and relevant calculation methods of mesh polypropylene fiber (M-PPF) and imitation steel polypropylene fiber (IS-PPF) in relation to RC and FRPRC beams require further investigation. This study tested flexural load capacity of various types of PPF-RC beams and PPF-FRPRC beams. Utilizing concrete beam calculation methods from the three international codes, the cracking and ultimate load of both PPFRC and PPF-FRPRC beams were calculated, subsequently comparing and analyzing the results against experimental data. The integration of different types of PPF enhanced the compressive and splitting tensile strength of concrete by 9.87 % and 53.22 %, respectively. The cracking load of RC beams, BFRP-RC beams, and CFRP-RC beams increased by 17.13 %, 6.10 %, and 7.16 %, respectively, while the ultimate load increased by 6.28 %, 11.54 %, and 10.52 %, respectively. In the assessment of Mcrexp/Mcrcal ratios derived from ACI (American Concrete Institute), CSA (Canadian Standards Association), and EC2 (Eurocode 2), the computational outcomes align most closely with the experimental results when following the EC2 specification. Regarding the evaluation of Muexp/Mucal ratios determined from ACI, ISIS (Intelligent Sensing for Innovative Structures), and GB 50608, the calculated results from ISIS and GB 50608 exhibit the closest proximity to the experimental results. The current standard used for determining the flexural capacity of concrete beams with varying reinforcement materials applies to the corresponding capacity assessments of diverse PPF-RC beams and PPF-FRPRC beams in this study. This validation demonstrates the viability and generalizability of the calculation methodologies for different types of PPF and FRP bars.