Experimental and numerical study of flexural properties in UHPFRC beams with and without an initial notch

Abstract This study investigates the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) beams with and without initial notch both experimentally and numerically. Parameters of the study were the modulus of elasticity, flexural strength, crack mouth-opening displacement (CMOD), crack tip-opening displacement (CTOD), notch-to-depth-of-the-notch ratio (N/D), fracture energy and the size of unnotched beams. Three-point and four-point bending tests were carried out on 150 × 150 × 600 mm notched and unnotched specimens, respectively. Subsequently, numerical analyses were conducted in a finite element software, ATENA, to study the effect of different N/D ratios. Similarly, size-dependent analyses were performed on unnotched specimens to investigate the effect of various cross-section sizes. Comparisons were made with equations available in the literature where relevant. Results showed that the presence of notch reduces the peak load by 47%; obtained results for the relationship between CMOD and central deflection were in good agreement with previous research. An increase in the N/D ratio led to an increase in the peak load. However, the converse was true for residual strength values for N/D variations at a constant width. Changing the size of the cross-section from 150 × 150 mm to 200 × 200 mm and 100 × 100 mm led to an increase of peak load by 2.44 times and a reduction in peak load by 3.97 times, respectively. Furthermore, fitting flexural curves were provided based on nonlinear regression analyses which fitted well with experimental results with coefficient of correlation, ( R 2 ) values mostly over 0.90.