The IUP Journal of Structural Engineering :
A Study on the Size Effects of Mixed Mode Fracture on Reinforced Concrete Beams Using Linear Elastic Fracture Mechanics

Article Details
Pub. Date : Oct, 2018
Product Name : The IUP Journal of Structural Engineering
Product Type : Article
Product Code : IJSE51810
Author Name : Abhishek P Varadai and Kiran M Malipatil
Availability : YES
Subject/Domain : Science and Technology
Download Format : PDF Format
No. of Pages : 14



Mechanics related to the study of propagation of cracks is known as fracture mechanics. Presence of cracks decreases the lifetime for which the structure is designed. Thus, crack propagation ought to be studied essentially to understand the stability of structures. Each structure contains inherent defects either miniaturized scale breaks or some other kind of split in concrete. So, it is very important to understand the behavior of the materials in order to predict crack propagation in the concrete. Fracture mechanics plays a very important role in dealing with such problems related to cracks in concrete. To be accurate in the analysis, it considers elasticity and plasticity in order to find out the macroscopic mechanical behavior of the materials. The load deflection of the crack of the beam is mainly due to stress crack opening relation. The results obtained from the various tests are sensitive from the production of the beam specimens and the execution of the tests depends on the size of the beams. It is observed from tests that the various size effects of the beam changes depend on the length and other parameters. The parameters may greatly vary as the size of the beam varies from higher to lower.


The paper uses Linear Elastic Fracture Mechanics (LEFM) principles to determine the effect of mixed mode fracture on reinforced concrete beams. There are three different modes of crack propagation:

  • Mode I (Crack opening mode)
  • Mode II (In-plane shearing or sliding mode)
  • Mode III (Tearing mode or anti-plane shearing mode)
If the beam undergoes cracking at the center span, then it indicates that the beam has been subjected to Mode I fracture, i.e., only tensile fracture has occurred, whereas if the beam undergoes cracking at tip of the notch provided at any distance away from the center span of the beam or it undergoes cracking at both tips of the notch and at the center span, then it indicates that the beam has been subjected to mixed mode fracture, i.e., combined shear and tensile fracture have occurred. Figures 1, 2 and 3 give examples of mode I and mixed mode fractures (Karihaloo, 2014).


Mixed mode fracture, Stress intensity factor, Size effects of beams

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