Reliability assessment on maximum crack width of concrete beams reinforced with high-strength steel bars

Abstract

Under the effect of load and time, cracks occur inevitability, leading to the issues of aesthetics, long-term durability, and even structural safety for reinforced concrete (RC) structures. Despite a promising economic benefit brought by high-strength steel bars, the application leads to a wider crack width for RC members compared with low-strength ones. Therefore, the quantification of the safety level on maximum crack width for RC members with high-strength steel bars is essential. In this paper, an experimental database that contains 1309 sets of data for crack width was constructed, and the prediction models of crack width were assessed in terms of model error. Then, the reliability assessment for serviceability limit state (SLS) of maximum crack width was performed systematically for RC beams with high-strength steel bars and low-strength ones within six well-recognized concrete design guidelines. The results showed that the reliability index for SLS of maximum crack width was lower for high-strength reinforcement configuration compared with low-strength ones. Furthermore, a parametric study was conducted to identify the effect on the reliability level of the maximum crack width. Subsequently, an optimum design procedure was given to control the maximum crack width for concrete members in terms of reliability level. Compared with low-strength steel bars, the required steel ratio was relatively small for high-strength ones with equivalent bearing capacity and safety level of crack width, indicating that the economic advantages of high-strength steel bars can be shown sufficiently by reasonable design.