How to determine which design method to follow
When designed properly, post-installed rebar can be just as safe as traditional cast-in reinforcement, as proven in European Technical Approvals tests. In fact, these connections have been used in everything from large buildings to bridges, but this makes the design method very critical to achieve a safe connection.
Hilti Engineer Zac Bouchabake explains that SA TS 101 should be used when it is determined that tensile load forces can be transferred directly through concrete, causing a concrete cone failure. On the other hand, the rules of AS 3600 can be used when the anchor point is in equilibrium without tensile stresses in the concrete, or when the post-installed rebar is forming a splice with an existing cast-in rebar. In the second case, only concrete splitting can occur.
“Strength is important because it determines how much load you can apply on the anchors. Every time you have higher bond strength, you’d expect a higher load resistance for a specific fixing”, he said.
The Hilti HIT Rebar method
Taking things further, the Hilti HIT Rebar method provides further optimisation for applications covered by EOTA TR23 and follows the AS 3600 approach. This method takes advantage of our high bond adhesives and can achieve anchorage length reductions of up to 70% when adequate concrete cover is applied, compared to the figures given in building codes.