The essence of this write up is to intimate Structural Engineers supervising building projects under construction of the need to carry out due diligence on reinforcing Steel supplied to site. The onerous will obviously rest on the Resident Structural Engineer.
The looming danger on the other hand is the Client’s ignorance in playing a major role in the procurement of this structural item without due diligence.
A ton of steel of the diameters stated below has equivalent corresponding pieces.
Hence, the modal sizes in a ton;
25mm – 21pcs
20mm – 33pcs
16mm – 52pcs
12mm – 92pcs
10mm – 133pcs
8mm – 210pcs
6mm – 373pcs
12mm @ 92pcs is requested to be supplied, what you get is, 10mm @ 92pcs for the price of a ton. If you are lucky to detect, you might be able to obtain a fictitious discount for a bedraggled deal. Similarly, for 10mm @ 133 pcs you get supplied 8mm @ 133 pcs.
The danger here for the Structural Engineer is that calculation outputs are usually specified, and if what is supplied is to be used, a reappraisal of the supplied diameter becomes inevitable.
It is easy to say that the supplied items should be returned outrightly.
The fraud by some manufacturers is that 12mm inscription will be seen on the supplied 10mm, same goes for other diameters. Arising from this fraudulent practise have resulted in 14mm supplied for 16mm and 22mm supplied for 25mm.e.t.c. These bars in equal numbers don’t have the same strength.
Simply put, 4 nos of 25mm required is not equal to 4 nos of 22mm.
(4 doses of 50mg of tabs is not equal to 4 doses of 25mg of same tab)
For those Clients that bridge the protocol of obtaining adroit Professionals, the integrity of the structural strength of the building may be compromised.
On the monetary aspect a ton of 33 pcs of 20mm is not equal to 33 pcs of 18mm. If the Structural Engineer is compelled to use the lesser diameter supplied to site, additional reinforcing Steel is inevitable to meet the required strength. it is only wise to request for the designed diameter and quantities, however, this is only visible for Corporate entities and discerning Clients.
For the Structural Engineer, it is advisable to design with the lesser diameter say 14mm for 16mm e.t.c. to conform with the trend of supply. For the QS, the per ton cost is suspect, when the lesser diameter is used, additional procurement will further be borne by the Client. It is pertinent to apply a reasonable percentage to the estimated quantity. Most Clients that choose to procure reinforcing steel at their own peril don’t accept fluctuations.
The Client should access or employ a competent Structural Engineer to confirm the reinforcing Steel diameter to be used for construction in situations where what is readily available are the lesser diameter. It is possible that exchange rates is taking it’s toll on this item. The increment in the prices of reinforcing steel could have moved from 220k per ton to 400k in reality if the previous trend is to be maintained. It’s a bitter pill to swallow, like every other item.
But building collapse resulting from the mismanagement of manufactured reinforcing Steel supplied to construction site will be a disaster waiting to happen.
In conformity with economic indices cement per bag recently moved from 2,700 to 3,500, and the 50kg content remains the same without compromising the quality.
The Structural Engineer is advised to carry out due diligence on the reinforcing Steel to be used on the site with respect to designed and supplied, and where possible recommend laboratory tensile strength test.
By ‘Niwo Balogun