The Insight: Concrete Condition - Cracked versus Non-Cracked Concrete
Here at ICCONS, we are often asked “I can’t see any cracks in the concrete, do I need to assume a Cracked Concrete condition when designing my concrete anchors”. Under AS5216:2021, the conservative answer is always yes, unless proven otherwise.
Concrete as a material is characterized by its compressive strength and demonstrates huge capacity when in compression. The same cannot be said in tension where steel reinforcement is required to minimize concrete cracking. Reinforced Concrete is therefore a composite material where the concrete is designed to be loaded in compression and the reinforcement loaded in tension. Knowledge of these basic principles is essential in understanding concrete compression and tension zones.
Definition of cracked concrete: In general terms, ‘cracked concrete’ refers to concrete that is likely to experience cracking during its design life. These cracks may result from the action of forces on the concrete or earlier due to the concrete shrinkage in the setting process.
It is also important to note that for seismic design, the concrete should be assumed to be cracked unless a comprehensive analysis demonstrates the concrete remains non-cracked throughout the seismic event.
In summary, incorrect determination of the concrete condition in which the fastener is to be installed may prevent safety-critical fasteners from functioning correctly leading to catastrophic outcomes. AS5216:2021 conservatively assumes all concrete is Cracked unless justified by Stress Analysis. For further information, please refer to AS5216:2021 available here: https://infostore.saiglobal.com/en-au/standards/as-5216-2021-99009_saig_as_as_2979723/
ICCONS has a wide range of Concrete anchors suitable for use in cracked concrete, that includes but is not limited to screwbolts, thru-bolts, drop-ins, cast-in inserts, and chemical anchors.