Prediction of Shear Transfer in High-strength Concrete Crack Interfaces

Shear behaviour of concrete is still a riddle, accurate prediction of concrete shear capacity is therefore a challenge. Shear transfers across concrete cracks primarily via aggregate interlocking based shear friction and via dowel action, amongst the former is considered as the major factor. It is found that the Contact Density Function (CDF) has the potential to quantify shear friction at cracked concrete interfaces. This function has mainly been used for normal strength concrete (NSC) (<60 MPa) and recent investigations show that it has to be modified when it is used for high strength concrete (HSC) , different aggregate sizes and large crack widths. The current study focussed on the modification of the CDF to suit high-strength concrete using the experimental results of nine pre-cracked push-off specimens which comprised of compressive strength up to 90 MPa, maximum aggregate sizes of 12.5/20 mm, and comparatively large initial crack width of about 0.5 mm. The results indicate a significant prediction inaccuracy when the existing model is used for HSC specimens. However, incorporation of a modification into the formulae is found to improve the prediction accuracy for HSC reasonably.