Building with pre-fabricated or pre-engineered metal building systems continues to increase in popularity. The efficiency and long-term benefits of building with steel drive much of the development, as does the need or desire to construct with environmentally friendly and sustainable materials.
One question that must be answered as the decision on the material is pondered is whether metal buildings are as durable as concrete. You know Whirlwind Steel will say yes, but we do so with a multitude of evidence to support what we say. In fact, in many ways, steel outperforms concrete and remains a better choice for a wide variety of designs and environments.
Steel is safer than concrete during both the construction phase and operations.
- Concrete must be mixed on site, increasing the amount of activity at the job site along with a higher risk of accidents.
- Pre-engineered steel buildings come ready to assemble, requiring less movement of materials and a safer work area.
- Concrete takes time to cure, creating a safety hazard until it is completely set.
- As soon as a metal building frame is erected, it is ready to go.
- In areas of high seismic activity, the flexibility of steel mitigates the threat of collapse and failure whereas concrete would crumble.
- Steel survives better in high winds because of its ductility.
- Steel is as capable as concrete in terms of fireproof behavior and mitigating the spread of flames.
Working with steel over pouring and forming concrete also results in less noise and vehicular pollution. There is no need for concrete trucks, dump trucks or other heavy machinery to enter the site.
Durability and Strength
Steel does not warp, split, crack or corrode when appropriately produced and maintained. Concrete, on the other hand, tends to crack due to repeated expansion and shrinkage during temperature variations.
Concrete is also prone to chipping and crumbling because of its brittleness. Because it is a composite material made of sand, gravel, cement and chemicals, some of the components absorb moisture or become damaged under circumstances that would not impact steel.
Steel has eight times the tensile strength of concrete and has a uniform molecular structure. The uniformity of the molecular structure makes steel a highly predictable building material.
A steel building is capable of withstanding winds up to 200 mph. In regions of high winds from storms and hurricanes, a steel building will survive where a concrete structure may not. It all goes back to the brittleness of concrete, making it prone to shattering instead of bending.
Steel buildings are designed to bend with the wind and deflect lateral forces to the walls and down to the ground. It is much more difficult to design a cost-effective building of concrete that can withstand such forces. It would be cost and design prohibitive to construct a concrete building of more than a few stories. The ductility of steel allows the building to sway slightly without losing cohesion or failing.
Both concrete and steel are resistant to fire. Both are unlikely to burn and will not spread flames. Innovative fire-retardant coatings and insulation increase its fire resistance to higher temperatures.
Increased fire resistance provides more time to evacuate a structure, and there is less chance the building will collapse.
Many people point out the disaster at the World Trade Center of 9/11 as evidence that steel does not have the fire resistance or strength that is claimed. However, the design of the twin towers did not account for explosive detonation. The experience has led to including blast-resistant design principles in the building code for high-rise structures.
Steel requires very little regular maintenance and is quickly and easily repaired. Lifetime maintenance requirements and costs remain low throughout the lifetime of the building.
- Steel is weather and sun-resistant and can be coated with finishes that expand that resistance.
- Steel also carries longer warranties than concrete due to its durability.
- A metal roof with a protective finish may be warrantied for 40 years or more.
- If steel becomes damaged, you need only replace the damaged portion with a steel replacement.
Concrete repairs take more time and skill and require more time to perform. The repaired area will not match the appearance of the surrounding material. The repair will likely cost more than a similar repair to a metal building.
Design flexibility is where steel really shines. While concrete can be cast in a variety of shapes, its lack of ductility limits the size and weight of various shapes. Steel has a high strength-to-weight ratio - it would take a heavier or larger amount of concrete than steel to build a similarly sized structure. Steel is readily formed into endless shapes and patterns without collapsing.
Without the strength of steel, open-span buildings would not be feasible. A sports arena, entertainment venue or other open space can only be built with steel. You can build spans of up to 150 feet without additional steel or concrete support beams obstructing site lines or interrupting the floor space.
When no columns are in the way, you can configure the floor space any way you want using temporary or semi-permanent partitions that are easily moved if the space must be redesigned for another use. A concrete building of the same span would have columns to work around, and certain configurations would not be possible.
Steel can repeatedly be recycled without loss of strength while concrete recycling is labor and material intensive. Recycled concrete is extremely limited in use, whereas recycled steel can be fashioned into anything you need. In fact, it is possible to de-assemble a steel building and reassemble it elsewhere if needed. Recycled concrete is only used as filling material.
Because steel is 100% recyclable, it has a high recycling rate, creating steel without the need for much virgin material.
Steel construction is less expensive than concrete construction in time, materials and labor.
- Concrete construction takes time to complete because it must be poured onsite and allowed to cure before proceeding.
- Concrete requires more laborers to pour and finish concrete properly.
- Pre-engineered steel buildings only require assembly, taking much less time to erect and complete the building and making it ready for the trades.
- Steel buildings may require a different set of skills from concrete construction, but the workers complete the building quicker, offsetting the labor costs.
- Steel framing makes it easier to plan and place utilities than concrete.
Steel construction overall is faster, cleaner and simpler than concrete construction. Building with concrete will not insulate you from price fluctuations in steel and transportation, and erection will cost less if you build with steel.
Steel is fire-resistant, wind-resistant and more likely to survive an earthquake than a concrete building. It may deform under certain conditions but will not fail.
Steel is simply the better of the two materials in overall durability and versatility.