Crack extension resistance for a general three-point bending concrete beam

Expressions of the crack extension resistance for a general three-point bending (TPB) concrete specimen were developed. Based on the proposed general expressions, the effects of span/height ratios on the fracture processes of TPB concrete beams were studied using two types of specimens, i.e. the beams with the same section but different spans and the beams with the same span but various heights. Results indicate that (1) the crack extension resistance curves (KR-curves) increased with the crack propagation. (2) The KR-curves and fracture process zone curves were not affected by the span/height ratios, i.e. the KR-curve can be considered as a criterion to describe the crack propagation in a structure. (3) The calculated crack tip opening displacement was not affected by the specimen span but increased with increasing the specimen height. (4) The stability analysis of crack propagation was also described based on the KR-curve.

Automated summary

Expressions of crack extension resistance for a general three-point bending concrete specimen were developed. The effects of span/height ratios on fracture processes were studied using two types of specimens. Results showed that crack extension resistance curves increased with crack propagation, and were not affected by span/height ratios. The calculated crack tip opening displacement was not affected by specimen span but increased with specimen height. Stability analysis of crack propagation was also described based on the crack extension resistance curves.