Types of concrete frame |
Type | Economic span (m) | Remarks |
One-way slabs | 4-8 | Economic across a wide range of spans but supporting downstand beams affect the cost, speed of construction and services distribution |
Flat slabs | 5-9 | Quick and easy to construct. Often the most economic method of construction. Holes require careful detailing |
Troughed slabs | 6-12 | A slightly greater structural depth, higher formwork costs and longer programme time is offset by the structure’s lighter weight, longer spans and greater adaptability |
Band beam slabs | 8-15 | Useful for long spans in rectangular panels making them popular for car park construction |
Two way slabs | 9-12 | Robust construction with large span and load capacities – popular for retail premises and warehouses, but downstand beams disrupt construction and service installation |
Waffle slabs | 9-14 | Slow to construct but useful for long spans |
Precast and composite slabs | 4-16 | Economic across a wide range of spans and loads. Increased speed and improved quality on site may be offset by long lead-in times |
Post-tensioned slabs and beams | 6+ | Insitu slabs and beams. Useful where depth is critical |
Typical amount of reinforcement allowances |
Suspended slabs | 90-135 kg/m3 |
Beams | 250-300 kg/m3 |
Columns | 200-300 kg/m3 |
Walls | 85-125 kg/m3 |