Model Error for Australian Code Shear Capacity of Concrete Structures

Abstract

Reliability assessment informs on the level of safety of existing structures. To do this, the variability in capacity and loading must be first quantified. Uncertainty in predicting capacity (known as model error or ME), when compared with experimental values, should be included. The modified compression field theory (MCFT) is found to closely predict the shear capacity in concrete members. The Australian standards for concrete structures include a simplified codified version of MCFT similar to that in the Canadian standards. While the ME for the codified MCFT in the Canadian standards is published, it is not known whether this is the same for the Australian-codified MCFT. Hence, this study aims to determine the ME for the Australian standards in concrete shear capacity estimated with MCFT. Based on a Super-T girder designed to AS 5100.5 (2017) [11], the response surface methodology is used to provide a surrogate shear capacity model based on the most important parameters. It is found the Australian ME is less than the Canadian ME. The calculated ME can be used for future reliability analysis of Australian concrete structures in ultimate shear. More broadly, the methodology can be used for determining ME for other codified models, and for other limit states such as ultimate bending.