Post-Peak Cyclic Behavior of Steel Fiber Reinforced Concrete under Bending

An overview of the flexural post‐cracking behavior of steel fiber reinforced concrete

“…The orientation number η , which represents the average orientation of all fibers in a cross section, can be determined by applying the following Equation: where N is the number of fibers detected through image analysis on the cross section of a beam. The orientation number was measured by considering the fibers crossing the entire cross section, since during bending tests the neutral axis rises rapidly, leading to a small part under compression and a major part under tension . Hence, the accuracy with regard to residual flexural strengths for the fiber orientation factor measured over the entire cross section area is similar to that measured over the bottom region only (close to the notch tip) …”

“…Tested beams were cut 1–2 cm behind the fracture surface (Figure ) and pictures of the cross sections were taken using an high‐definition camera; fibers are easily distinguishable on the images (because they reflect light of the camera flash) and a color threshold is set in order to count and determine the fiber orientation (Figure ). The image processing algorithm was developed by using Matlab 7 (The MathWorks, inc., US) . Basically, a fiber in the cross section is generally visible with an elliptical form, whose in‐plane angle ϕ i is depicted in Figure a.…”

“…These parameters were related to the main flexural nominal strengths adopted by MC2010 . Moreover, special attention is devoted to the influence of fiber orientation on flexural post‐cracking residual strengths by using the image analysis technique on sawed cross sections of numerous SFRC beams.…”