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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For too much reinforcement to be incorporated in concrete structures, the reinforcement bars are sometimes groups because:
(i) It facilitates placing of fresh concrete with more space available;
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Acetylene gas is commonly used for gas welding because of its simplicity in production and transportation and its ability to achieve high temperature in combustion (e.g. around 5,000o F).
Currently, there are three common non-destructive testing of weld, namely radiographic inspection, ultrasonic testing and magnetic flaw detection test.
Considerable residual stresses are induced in connecting steel members after the welding operation. The local temperature of steel where welding takes place is higher than the remaining parts of the connecting steel members.
In the design of butt weld strength, it is generally assumed that its strength is at least equivalent to the parent metal. To enhance proper welding operation, the gap between two metals to be welded should not be too small, otherwise the root would be inadequately fused during welding and the butt weld strength would be reduced. On the other hand, the gap should be not set too large because the weld metal would simply pass through it. The function of the gap between adjoining root faces is to increase the depth of penetration down to the root of the weld.