When Does Concrete and Tilt-up Construction Make More Sense than Steel Buildings?

http://www.tiltup.com/commercial-construction-articles/concrete-panel-construction/

This article is clearly written and highly informative, stating the key factors for when it is advantageous to use concrete tilt up construction over steel. Although written in favour of concrete construction, the author describes both the advantages and disadvantages of both materials, expressing an opinionated yet not biased view.

Firstly the size of the building is raised as a major consideration as to what construction method should be employed. Although steel is generally a more expensive raw material, it can be a cost effective alternative for smaller projects, say less than 50, 000 square feet. This is due to the expensive construction processes associated with concrete – for example the rental of a large crane to lift the panels in place. However if the size of the building is larger than 50,000 square feet, the comparatively inexpensive cost of the concrete starts to offset the project’s fixed costs and so becomes more advantageous.

The next issue raised in the article is the location of the site. This is due to the fire codes, building permit requirements and other standards. Agricultural and lightly populated areas tend to have fewer codes to abide to, compared to more densely populated areas, which in contrast can be quite strict. This can even result in steel buildings not being allowed to be built in certain areas due to the characteristics of the material. In other cases the steel buildings have to spaced further apart than tilt up concrete buildings and so this is why more concrete buildings can be seen in the middle of cities.

Concrete and tilt up offer much more protection from fire compared to steel. Although steel is not combustible, it can not be classified as fireproof as the material loses structural strength when exposed to high temperatures. As in the case of the World Trade Centers - although the initial impact of the crash did cause structural damage it was the failure of the steel columns due to the extreme heat that resulted in the collapse of the tower.

Another consideration when choosing which construction method to use is the intended purpose of the building. ‘In general steel buildings work very well for storage buildings, indoor sports facilities, work shops, and aircraft hangers, but they are less suited for higher-trafficked buildings’. This is again due to the different qualities each of the materials posses. In general, steel is less durable than concrete and therefore will not be as stable in the event of bad weather or a heavy duty machine accident. Damage is localized when caused by a vehicle and it is less expensive to repair for a concrete building than steel. Concrete is also resistant to corrosion, rot or rust, an aspect that steel is very susceptible to and therefore has a shorter life span without repair.