Fracture mechanics of flanged reinforced concrete sections

Abstract

This work reports on the application of fracture mechanics to study the flexural behavior of T-section reinforced concrete beams. Twelve beam specimens; nine flanged and three rectangular, were tested experimentally in a four point bending test in a displacement controlled environment. Three main parameters were considered: the ratio of the flange width to web thickness ( B / b ) , the ratio of slab thickness to total height ( t s / h ) , and the ratio of the tension reinforcement steel. The beam’s size was 70×300×1400 mm, the reinforcing steel’s tension ratios varied between 0.48%, 0.61% and 0.73%, the values of ( B / b ) varied between 1, 1.5, 2, 2.5 while the values of ( t s / h ) varied between 0, 0.1, 0.15, 0.2. All the beams have a constant span/depth ratio of 4, and initial notch/depth ratio of 0.3. The concrete used had cube strength of 25 MPa at the time of testing while the reinforcing steel has a nominal yield strength of 530 MPa. Measurements included load, steel strain, concrete strain and deflection. The Fracture Mechanics algorithm proposed by Baluch was employed to analytically investigate the fracture behavior of the T-shaped reinforced concrete beams. The results obtained from the Fracture Mechanics approach were checked against the experimental results. Moreover, a finite element analysis was carried out for the same purpose. The results of both the Fracture Mechanics approach and the finite element analysis were found to be in good agreement with the experimental results. Yet, both approaches underestimate the maximum capacity of the beam.