Evaluation of Cracking Limit State Provisions in Different Standard Codes and Numerical Study of Cracking Behaviours of Reinforced Concrete Elements

Abstract

Cracking in reinforced concrete structures affects the serviceability and durability of structural members. These effects are mostly occurred due to excessive size of crack width on the sides of RC members. As the crack width increases on the surface of flexural/tensile loading members, corrosion occurrence is probable to the embedded steel reinforcement. To overcome such problems, different standard codes provide analytical expressions to limit the size of crack width. Thus, to have safe and durable structures, comparing the expressions of crack width limits in different standard codes is important to get best practices among the codes. In this study, the analytical crack width expressions of American, British, and Ethiopian Standard codes were considered. The analytical crack spacing of Ethiopian standard code and Model code (MC2010) were also compared. The study is made through calculation of crack width and crack spacing in the respective codes, comparing it with experimental results in previous studies and Finite Element Numerical modelling in Abaqus. In the comparison, the effects of parameters such as concrete cover, bar diameter, and loading types were discussed. Firstly, the analytical results of each code crack width limit expression were compared with the experimental crack width results. As a result, while considering the estimation of crack width in different codes, it could be observed that the ACI code gave a relatively good fit to the experimental crack widths than ES-2 and BS codes. On the other hand, for the estimation of crack spacing, the value estimated by MC-2010 gives relatively closer results to the experimental crack spacing than ES-2. Secondly, to code’s crack width and spacing analytical comparisons, the 3D nonlinear finite element model, Abaqus, was used to predict the cracking behaviour of reinforced concrete tensile loading beam. Accordingly, the simulation crack patterns result indicates a good fit to that of the experimental crack patterns result. In conclusion, when considering the cases of all codes, and based on the percentages of variations, it is observed that the existing codes need to improve the expressions for crack width calculation.