Design criteria for strut-and-tie modelling in Hong Kong practice

Strut-and-tie modelling has proved a very useful method in the analysis and design of non-flexural components of reinforced concrete members. Examples of design codes encompassing the strut-and-tie model (STM) provisions include Eurocode 2 (EC2), the fib Model Code 2010 (MC2010), the Canadian Standard (CSA A23.3-04), the American bridge design specifications (AASHTO LRFD 2020), the American Standard (ACI 318-14 and -19) and the Australian Standard (AS 3600:2018). Nevertheless, the application of different assumptions, model types and methodologies means that the strength acceptance criteria for struts, nodes and bearings vary within the literature and design codes. Unifying the STM design criteria is thus encouraged, to facilitate worldwide use of the STM in the design of non-flexural components, particularly for places such as Hong Kong that have not yet developed the localised design criteria for the STM. In this paper, the proposals set out in the literature and the provisions in the above-stated design codes are reviewed and compared with each other. Calibrating with the existing literature and design provisions, unified STM design criteria for struts, nodes and bearings with localisation are proposed for application in Hong Kong. The proposed design criteria are then applied to the STM design of a cantilever deep beam.