Circular hollow section was available for many years until in 1960s for the approval of square hollows section and rectangular hollow section.
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Circular hollow section was available for many years until in 1960s for the approval of square hollows section and rectangular hollow section.
It is not uncommon that starter bars are bent up within the formwork as a measure of temporary protection. Later, after the concrete is placed and formwork is removed, the steel bar reinforcement would be pulled out and straightened.
Indeed past research showed that large-diameter reinforcing steel appeared to be weaker under fatigue loading conditions. Therefore, in some standards the stress range for testing fatigue of steel bars are reduced for increasing bar size for the same reason.
In BS4449:1997 it species a re-bend test of steel reinforcement where
reinforcing steel is bent 45o at 100oC for an hour and then bent back by 23o.
It is not uncommon that steel reinforcement is bent prior to installation into concrete structure. However, upon bending process steel reinforcement may fracture owing to the following reasons:
(i) The ribs on steel bars serve as location of stress concentration which is a potential weak point for fracturing.
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