| Commercial Construction - Why We Build in South Florida the Way We Do|
|Anyone who comes from another area of the country is usually puzzled by the way we build in South Florida. Most commercial buildings in the north of the country are steel structures and use as little concrete as possible. South Florida, on the other hand, tries to minimize the use of steel and uses concrete much of the time. Why do this?|
Concrete is a wonderful material. It is also a very forgiving material. What I mean by this is that once it is poured all the connections are solid. For example, there are no joints between beams and columns which could come apart during a hurricane. Unlike a steel system, which must have perfect connections between beams, floor decking, and columns in order to survive a hurricane, concrete, once it hardens, is very difficult to take apart, if the steel reinforcing was designed correctly. In addition, concrete is a natural fire-retardant.
While steel joist systems must be fire protected, concrete joists are naturally fire-proofed. In precast systems such as double-T's, PSI's, etc., the concrete is the fire protection for the reinforcing steel. In the case of steel joists, for standard buildings such as schools, offices, retail stores, the steel roof structure must be fire-protected, so some kind of fire-protecting drop ceiling must be provided or a fire-proofing material must be sprayed on the structural steel members.
Another reason South Florida uses concrete instead of steel systems is that we have few steel plants where steel joints, beams, and columns are fabricated. On the other hand, concrete trucks are available from a number of local providers. Also, the workers in the concrete trades are very knowledgeable as they work in this medium every day.
As a practicing architect I saw the difference between steel and concrete up close after Hurricane Andrew. Although today we have additional requirements for making sure steel structural connections are done correctly, at the time of Hurricane Andrew the contractor was often allowed to design his own connections. As a result of this practice, I did not see any standing metal framed buildings (they were mostly gas stations) south of Kendall Drive after the hurricane.
Steel buildings can be well designed and stay standing through a hurricane. But for this to happen, all connections must be designed and installed correctly. For me, there are no more solid connections than concrete beams and columns poured together.