Crack width control in RC beams: experimental and analytical results

Abstract

In order to satisfy the required level of reliability, the structure has to be designed so none of the ultimate and serviceability limit states will be reached within the expected service life. By undertaking measures for ensuring the required durability, its serviceability is directly affected, as well as its load-bearing capacity, which may be endangered due to the dilapidation of the structure. Limitation of crack width and the adequately provided concrete cover, which primarily lead to corrosion protection of steel reinforcement, are one of the basic and maybe the most important preconditions for ensuring the required durability. Despite the wide range of knowledge gained through numerous experimental and theoretical studies, there are still certain dilemmas regarding the implementation of models given in the codes for crack control. In order to determine the influence of long-term sustained load on the serviceability limit state-crack control and to estimate the level of accuracy of the considered analytical models, an experimental program on RC beams was realized. Eight beams with dimensions 15/28/300cm were made and monitored in a laboratory environment with constant ambient conditions. This paper presents formation and development of the cracks in the considered time period of one year. An overview of the obtained results using several modern analytical models for crack prediction is also provided. In this paper, the results show that the modern analytical models given in the standards with satisfactory accuracy can predict the serviceability limit state-crack control due to long-term load.