The development of steel structures in High Rise Buildings

 

NATWEST BUILDING LONDON                HOME INSUREANCE BUILDING CHICAGO

When coming to a conclusion about the type of material to use, we must evaluate the advantages and disadvantages of steel. The main advantage of steel is that it is good in compression and tension making it ideal for the great range of applications whether it be bracing, horizontal beams or steel piles in the foundations. However the material properties cannot be the only reason for its strength but also the structure used.

The weight of steel can be important to the structures strength however floors nearer to the base have much more chance of failure due to the above weight being much heavier at the bottom rather than at the top, this is why high-risers are engineered by mechanically driving piles deep into the foundations to stabilise the building and carry the weight of the whole building. This is also done by bracing the building in strategic areas as add strength and reduce movement. In a typical skyscraper substructure, each vertical column sits on a spread footing. The column rests directly on a cast iron plate, which sits on top of a grillage. The grillage is a stack of horizontal steel beams, lined side-by-side in two or more layers the grillage rests on a thick concrete pad poured directly onto the hard clay under the ground. Once the steel is in place, the entire structure is covered with concrete. One major advantage of the steel skeleton structure is that the outer walls called the curtain wall. This lets architects open the building up as much as they want, in stark contrast to the thick walls in traditional building construction.

Steel may be a useful material however there are disadvantages from a practical side when considered in the use on site. The weight of hot rolled steel can be massive to try and lift especially for builders working at high heights which may be regarded as a health and safety issue when moving around the site. If that’s the case the uses of mechanical equipment such as cranes are needed.

Over time skyscrapers have begun to look more increasingly futuristic to match a new era in building construction. Architects have designed ideas as to certain shapes which may not be achieved by using the set of products the manufacturer has to propose. And so by not being attached to a certain product portfolio which may be used in more conventional cases Architects can achieve more complex buildings.

However bespoke manufacture does have its disadvantages. Manufacturing on a small scale results in much higher costs as the tools to extrusion the structure have to be made, the trouble with this it will be costing heavily into the budget. Not only this but construction being one of the biggest industries to use up materials such as Iron ore, reusing such materials at the end of the buildings life on other developments. The result of cross sections will result in more wasted steel as it cannot be reused. The procedure of recycling is not as environmentally friendly the reason being is the temperatures needed to reach are high to break the bonds of steel in order to reform it.

To conclude to this steel has been an important material to use on skyscrapers however as with every material along with its strengths it also has its drawbacks. Steel when used to help buildings add to its floor levels this is an amazing growth in buildings reaching storeys up to current amounts of 100+ floors.

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