Incorporating Pre-Existing Cracks in Structural Assessment of RC Structures

Abstract

Cracks in reinforced concrete (RC) structures can be detrimental as they grow beyond the limits. Cracks should be included in structural assessment methods to ensure the durability and load capacity of existing structures. However, conventional models used in the assessment of existing structures do not reflect the real cracking condition which implies that advanced assessment methods are required. In this study, pre-existing cracks were introduced into finite element analysis to identify the ductility, failure characteristics, and ultimate capacity of cracked structures. A beam specimen taken from the edge beams of an existing bridge had been subjected to a four-point bending test, and the results are used in this study for validation purposes. The specimens showed varying levels of cracking due to loading as well as reinforcement corrosion during the service life. Five different analyses were carried out to account for the effect of loading cracks and corrosion cracks based on two crack modeling approaches, namely weakened element approach and weakened bond-slip relation approach. The results showed that the failure of the beams was caused by anchorage failure. The differences in the load capacity predicated by different models are discussed. It was observed that incorporating pre-existing cracks by using weakened elements and weakened bond-slip relation approaches can be a practical method to model and assess cracked RC beams.