The lightweight steel fabrication includes a 100mm wide top flange which eliminates the necessity for a plywood infill, so cutting down maintenance costs. Heavy duty pressings are fitted to the beam ends ensuring adequate protection against site abuse. These incorporate a tongue location for the drophead. Panel retaining lugs have a tapered wedge action for quick positive location of panels, ensuring tight joints and minimum grout loss. When beams are in the horizontal position they cannot be accidentally dislodged
The Technique of Early Striking
Early striking is a technique whereby the formwork is removed 3 to 4 days after pouring a slab, but the supporting structure of scaffolding or props remain undisturbed until the concrete is strong enough to support its own weight over its full span. Concrete generally takes 28 days to attain its full constructional design strength. Most engineers will only permit the complete support to be removed after about 10 to 14 days, depending on the ambient temperature and cube strength tests.
The first calculation opposite shows that the load safety factor of the slab of 3 days, spanning the short distances between the temporary supports, is certainly greater than 10 to 14 days over its full Span, although other factors may have to be considered. The most critical stress in early striking is the punching shear at the drophead. The second calculation, based on the most severe condition of relatively light slab, shows a safely factor of 5 to-1.
With today’s high costs of formwork it is important to use it as frequently as possible. Traditional formwork locked in site for 10 to 14 days with a pouring cycle in excess of this is obviously outmoded by Metriform with its facility to speed the cycle of operations. This practice has been widely accepted in Europe for more than a decade where the rising costs of material and labour have proved that the Metriform system of early striking is safe, efficient and truly cost-effective
