reinforced concrete structure VS steel structure
reinforced concrete and steel possess good characteristics in terms of strength and ability to carry and transfer loads. the using of steel or concrete structure will depend on the height and span of the structure, the material market, foundation conditions, local building codes, and architectural considerations. in this article, I will compare between steel and reinforced concrete structures.
- Fireproofing: heating of the steel will cause a significant reduction of steel strength. therefore building fire will pose a risk for steel structure. also, steel is a good conductive material. it will transmit heat to other members quickly. on the contrary, concrete offers high-temperature resistance caused by fires. but the minimum cover for steel should be met for concrete to endure fires.
- maintenance and durability: steel corrosion is a challenging obstacle for steel structure exposed to air and water. rusting of steel adversely affect structures. rust will reduce steel cross section and strength. therefore it is significantly important to protect steel from rust.for concrete structure exposed to a harsh environment. such as salt water. the ingress of chloride will cause rust for reinforcement and concrete spalling. another example is sulfate. sulfate will react with concrete and cause expansion of concrete. this will create internal stress causing cracks and concrete spalling. using of some admixture such as silica fume and GGBS will reduce concrete permeability and reduce the ingress of harmful chemicals.
- strength/weight ratio: the weight of steel is relatively small. therefore strength-weight ratio is high. this property makes the steel suitable for long-span structure, high-rise building, structures resting on soft ground. concrete has a high dead load. as a result, the strength/weight ratio is less than steel. this will lead to a member with significantly big dimensions for long spans.the recent use of prestressed reinforced concrete offers a great enhancement to concrete structures strength. this lead to a higher span-depth ratio.
- time for construction: steel structure can be constructed rapidly. erection of steel can be done quickly and this will reduce the time and cost of the structure. concrete consuming more time. the constructing of a concrete member will pass through different stages such as falsework erection, formwork, casting of concrete and waiting period for curing. however, using precast concrete can reduce construction time for reinforced concrete structures
- Cost: The steep increase in steel price result in an increase in steel structure cost. concrete price remains stable with no major change. the price of structures will depend on many factors such as materials, the time required for construction and other factors. therefore. the price may vary if these factors changed with time.
- tensile strength: concrete possess a low tensile strength compared to compressive strength. that prompt the using of reinforcing bars. even with using reinforcing bar crack will develop in tension zone and this will reduce durability. steel structure doesn't encounter this issue.
- ductility: steel undergoes a large plastic deformation before failing this called ductility. this deemed to be a good property because the structure will not fail quickly under shock loadings such as an earthquake or sudden loading. different factors affecting the ductility of reinforced concrete. for example, increasing the amount of steel and member dimension. reducing member dimension and amount of steel will increase the ductility of concrete members.
- workmanship: concrete structures required less skilled persons compared to steel structure.