Background and Investigations of
the AS 3600:2018 Shear Rules
as applied to Prestressed Concrete

ABSTRACT

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This thesis investigates the background to the new shear rules in Australian standard AS 3600:2018 Concrete Structures and compares them with the AS 3600:2009 shear rules. As most of the newly introduced equations and requirements in the AS 3600:2018 shear rules come from recent research into reinforced concrete, this thesis, moreover, examines several examples where the new shear rules as well as the old ones are specifically applied to prestressed concrete, in order to compare differences of the results and ensure there comes no unusual result with application of the new shear rules.

The examples in this thesis include simply and continuously supported rectangular beams, band beams and hollow section slabs. Various cross-section dimensions and imposed actions are particularly given to the simply supported rectangular beams that are commonly believed as the simplest structural members.

Focusing on previous research papers and other standards, the background investigation into the new shear rules suggests that they are mainly based on and adjusted from the shear provisions in fib Model Code 2010 (MC 2010) which fundamentally adopts the simplified modified compression field theory (SMCFT).

According to the examples, the new shear rules are less conservative, giving around 10% higher value of shear capacity towards band beams and hollow core planks. For rectangular beams, however, the new code gives concrete shear capacity which is around 13% lower than that from the old code, but the required amount of shear reinforcement is slightly larger than the corresponding requirement in old provisions. Although there exist certain differences of the results by using the new code, they are reasonable and acceptable, which exert no adverse influence upon the final design of the structural members.