An evaluation of fracture mechanics quarter-point displacement techniques used for computing stress intensity factors

Engineers have made extensive efforts to predict cracking which is inherent in most structural systems. This paper evaluates two nodal displacement methods used for prediction of cracking in massive concrete structures. The methods are based on linear elastic fracture mechanics principles because the object of the research is massive concrete structures. The methods evaluated are the displacement correlation technique and the quarter-point displacement technique and must be implemented through the use of quarter-point elements (QPE). Since assumptions exist in development of the method for computing stress intensity factors, it is necessary to quantify the effects of these assumptions for use with QPEs of different sizes. Four different problems with closed form solutions are analyzed using five different meshes around the crack tip. Results from these analyses are used to draw conclusions regarding the ability of nodal displacement methods to predict stress intensity factors of cracks.