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, (R2) values mostly over 0.90.