Steel Structures or Reinforced Concrete?
Updated: Dec 27, 2020
Every construction project might have to start with imaginations for the question “how will it look like?” but at the end of the day, reality brings us to a more valuable question - “how and what is it made of”?
At any scale, construction projects require wise and careful decisions because it is definitely a matter of no turning back. Misguided decision can hurt us in many ways - wasted time, effort, and money at the least.
To figure out better, some pros and cons of Structural Steel and Reinforced Concrete are explained in different aspects as follows:
Steel elements has small, compact cross-sections making them approximately 60% lighter than concrete. Reinforced concrete members are bulky and may reach 2700 kg/m³ in weight.
Steel Structure is economical. Huge portion of the market supply comes from recycling, making steel much cheaper than other materials. Being lightweight, it delivers huge reduction in labor cost due to easier handling and transportation and faster installation.
Concrete has many ingredients such as cement, sand & gravel, water, and various additives. And to produce a reinforced concrete member, reinforcing bars must be integrated then formed and cast to the desired section. The number of ingredients and its lengthy assembly results to high construction expenditures.
According to a study, typical Steel Structures framing system costs 5 to 7% less than reinforced concrete framing system.
Steel has the highest strength to weight ratio among building materials, including concrete. Steel is eight times (8X) stronger than concrete in tension and shear; steel is resilient unlike concrete; and steel has better resistance to tensile, compressive, and flexural stress.
Japanese engineers generally refuse to use concrete for above-grade structures because it is rigid, weak and heavy, and quality control is a difficult task to perform.
Steel Structures components are fabricated offsite while reinforced concrete components are mostly cast-in-situ. Using Steel Structure has a huge advantage over reinforced concrete in this scenario because fabrication of multi steel components can be done simultaneously while reinforced concrete components are cast step by step, part by part, one at a time with 28 days interval (curing) after another.
Furthermore, given that Steel Structure is relatively lightweight, structures especially steel buildings with steel frame require smaller foundations than reinforced concrete structures. When modifications are necessary, simple removal of steel structure member is way more possible than demolishing a bulky reinforced concrete member.
Steel structures construction also deploys less number of manpower and skill trades. Reinforced concrete construction at the other hand needs enormous labor force to deal with its many processes – steel works, carpentry, casting, masonry, etc.
Concrete can be easily formed into limit-less desirable shapes but unlike steel, they have limited capability to span huge heights and distances. Steel Structure members can be laid-out in long segments without the need of intermediate supports, eliminating obstructions thus maximizing spaces.
Steel Structure and reinforced concrete both produce structures that are strong enough to withstand fire, strong winds, heavy snows, termites, and fires. However, steel structures might have the most significant advantage over reinforced concrete structures when comes to behaving against Earthquakes.
Lightness and ductility of steel helps the structural frame to absorb and reduce earthquake’s destructive impact. High-strength steel connections allow slight deformation at the joints but manage to hold members from separating, preventing easy collapse of the building or sections under stress. According to The New York Times, steel has better performance than concrete in earthquake zones.
Sustainability & Environmental Impact
Up to 90% of all Steel Structures in the market today is created from recycling. Steel can be recycled over and over without losing its strength. The Steel Industry has maintained greenhouse gases below allowable manufacturing levels and still getting better. Concrete ingredients are natural to our environment, meaning they are not harmful to our world.
How About Combination of Steel Structures and Reinforced Concrete?
BUT, what if the two materials are used together in putting up a composite structure? Will it be as strong as it gets. This is what to find out in the next part.
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