Advantages and Disadvantages of Steel Structures!
Monalisa Patel is a Structural Engineer who has earned her Master’s degree (ME) from the L.J College of Engineering and Technology Ahmadabad in 2018. She is an Engineer (Civil) at SDCPL – Gharpedia. Helping people to solve their queries about construction is her passion. Apart from being blogger, she also participates in structural design at SDCPL. She is reachable on LinkedIn, Twitter, Instagram & Facebook.
If you really want to assess the importance of the steel structures in a construction, it is difficult to summarize the utility and advantage of steel at one go. There is so much to say about the leverages of using steel structure! Using steel has become a common practice mainly because of the manifold benefits and higher stability of steel structures within a reasonable cost.
From skyscrapers and bridges to beautiful contemporary houses, steel is used in almost every type of structure. It has become the leading building material in the construction industry because it provides the leverage of excellent durability and endurance in a structural design solution, depending upon the shape and geometry of the structure.
According to ‘Lorraine Farrelly’ (Author of construction+materiality), before the use of steel in construction building became a common practice, the weight of the building material and the forces of gravity and compression defined the endurance, chance of stability in structure, and its architectural possibilities.
Advancement in the use of steel in construction industry brought in a new conceptual way of thinking about new but enduring constructional structures. As steel has higher scale of tensile strength, it allows development of new structural systems (such as cantilevers) and offers unwavering support to build far-reaching aesthetic possibilities (such as gravity-defying skyscrapers) for a construction or related project.
Use of steel is steadily increasing all over the world in construction projects and also in civil engineering related fields. Steel framing is an effective construction method as compared to others. In this article we have discussed the pros and cons of the steel structures
Advantages of using a Steel Structure
One of the most evident advantages of using a steel structure in construction is the ability of steel to span greater distances with steel ceiling joists. This allows engineers to expand their options, allowing them to create new/large space using steel products that just weren’t available with other materials.
A steel structure is highly recommended for large span and heavy structures which befits all types of Industrial buildings. Lower floor to floor heights can easily be constructed using staggered truss, girder slab, and castellated beam construction. Extremely long open spans are possible using steel that would not be possible to implement in concrete or with wood support.
The most economical and general shape for a prefabricated steel building is a basic rectangle. However, steel is also used to create more complex designs. Steel’s greatest design asset maybe its ability to span long distances without interrupting the related interior columns. That is why aircraft hangars builders use steel framing. A clear span interior space provides more floor-plan flexibility. It also allows greater freedom for later renovations and changes. It is a simple-to-design cantilever made with steel.
02. Strength and Durability
Structural steel components are stronger and lighter than the components made of weight-bearing concrete or wood. Weight-bearing steel fabrication is 30%-50% lighter than its wooden equivalent. This makes construction of steel structure stronger and more durable than traditional wooden structure.
Besides offering durability, a steel structure can withstand extreme forces or harsh weather conditions, such as earthquakes, strong winds, hurricanes and heavy snow to a larger extent. They are also rust-proof and, unlike wooden structures, they are not affected by termites, mildew, bugs, mold, and fungal contamination. And also, they are more fire-resistant compared to wooden/RCC structures.
03. Light in Weight
This may be surprising to know that if you weigh 2×4 square feet piece of wood and 2×4 square feet piece of steel, the steel would weigh more due to its density. However, when steel is used in framing, the design of beam will cause it to be lighter than a structurally sound wooden/concrete beam design.
04. Easy Installation and Speed in Construction
Steel parts in a steel structures are pre-manufactured to a specific design inside the manufacturing plant/fabrication shop and are shipped out in ready-to-be erected condition. Hence it speeds up construction time significantly. So, it is possible to complete large-scale projects in a shorter period than usual.
According to ‘Francis D. K. Ching’ (Author of Building Construction Illustrated), conventional steel structures are constructed out of hot-rolled beams and columns, open-web joists, and metal decking. Since structural steel is difficult to make on site, it is generally cut, shaped, and drilled in a fabrication shop as per the design specifications; this can result in comparatively fast and precise construction.
Due to easy-to-make parts of a steel structure, it is hassle-free to install and assemble them on site, and also there is no need of measuring and cutting of parts on site.
Steel is incredibly versatile as it can be molded into almost any shape, which makes it an attractive option for both residential and commercial buildings. Architects may let their artistic imaginations run wild, while still having the ability to design and construct a building that is both strong and safe.
Similarly, for the adaptability to the versatile design of large, clear span buildings such as airport, terminal buildings, auditorium, halls, agricultural buildings, warehouses, and indoor areas, there are hardly any alternatives to steel structures.
Flexibility is one of the great advantages of steel structure, which means that it can be designed as per the required needs. This helps designing a steel structures in such a way that it can withstand heavy winds or earthquake, especially in case of the bridges or tall towers.
The quality of ductility refers to the feature of steel structures’ stability if exposed to huge force. Steel, in general do not crack like comparatively brittle materials like concrete. This property of steel permits steel buildings to bend out of shape, or deform without collapse if there is any breakage risk, thus giving warning to the inhabitants to vacate beforehand. Breakdown for the steel structures neither happens overnight nor a steel structure rarely can collapse. That is why steel structure buildings are less affected by earthquakes. In brief, a steel structure will give you time to get out of it, in case of the threat of a sudden collapse.
08. Easy Fabrication in Different Sizes
Steel studs are available in a variety of sizes and can be manufactured as per an order. This means they can be customized to bear specific loads in buildings of all different sizes and types. While, wooden/concrete beams are not readily available in customized specifications.
09. Fire Resistance
Steel structures are highly fire resistant as compared to wood, and it reduces the fire accident risk to a building. The spread of fire gets reduced if there is more steel structure in a building. Special flame-retardant coatings are used to increase this property of structural steel.
Steel structures are highly fire-resistant as compared to wooden structure as wood is a combustible material and less fire-resistant as compared to RCC structure
10. Pest and Insect Resistant
Structural steel/concrete components are termite proof and these are not the consumables of mammals or bugs. In comparison to wooden structures steel structures need lesser maintenance. Steel structures also do not require any insect resistant treatment.
11. Moisture and Weather Resistance
Steel structures are wonderfully moisture resistant although this privilege may get slightly compromised depending on the carbon content of the steel being used for the structure. Hot zinc coating and extra powder treatments for enhanced rust resistance will make a structural steel component even more resistant to the effects of water – an important consideration for components exposed to the weather fluctuation and abrasive effects of outdoor climate.
Steel products can be changed or adjusted according to the owner’s requirement. For instance, wall made of steel can be altered or repositioned easily in order to widen the space or create a new interior building layout. This ability to adapt to changes permits for easier expansions, at the same time it helps in extending the lifespan of the structure.
Steel is light in weight as compared to timber/concrete, which makes it easier to transport and hence, reduces fuel costs and quicken project schedules. Aside from this, it is also energy efficient and can be recycled, hence, creates minimal raw material wastes. Since the steel parts are manufactured in the plant, there is no waste on location. However, the cost ultimately governs everything.
Concrete is economical where cheap labor is available i.e. in undeveloped countries. Cost of RCC structure is more in developed countries due to expensive labor. Wood is definitely becoming prohibited factor in work due to its high cost. Also, if wood is used in per square feet of construction, you will need more cubic feet of wood or concrete than steel structures of the same area.
However, a steel structure is not that cost-efficient in all conditions. The cost of structure also depends largely on its type and functionality. If you want to construct large span building, it is advisable to use steel. While cost of small structure with steel will be more as compared to wood/concrete.
Also Read: Repairing of Corrosion Damaged Concrete
14. Environment Friendly
Steel is one of the most recyclable materials in the world. Using recycled steel saves natural resources and energy to a large extent, which in turn, lowers the cost of producing new steel products. On the contrary, concrete is almost non-recyclable and wood can be partly recycled as compared to steel.
15. Energy Efficiency
However, a house, built with steel can actually be less energy efficient than a wooden building. Metal transfers cold and hot temperatures 400 times faster than wood. But additional insulation has to be used to stop this ultra-fast transfer of heat, specifically wrapping steel framing with rigid insulation in addition the use of conventional insulation between studs. Once the problem of insulation and energy efficiency is well treated, (if possible) it will no longer remain a limitation for steel construction.
Also Read: Different Types of Steel Windows
16. Improved Construction Quality
Steel buildings do not age and may get worsen like wooden/concrete structures over time, so as a homeowner you don’t have to worry about any feeble spots. Steel is dimensionally steady, no anxieties about distorting with climate changes. The service life is good without hefty maintenance cost.
17. Temporary Structures
Steel structures can be easily built using various methods such as welding, bolting or riveting and can be also disassembled without hassles. This reduces the time taken to make a temporary structure, and hence professional steel fabricators use steel for temporary structures. This is also favorable when you want a strong structure within a short span of time.
18. Safe and Resistant
Steel structures are conspicuously more blaze resistant than a wood/RCC construction; steel/concrete is furthermore unaffected by termites, bugs or rodents as well as mold or fungi. A steel/RCC structure does not have to be treated with chemicals as it is a prerequisite for the wood. Lastly, a steel structure is well grounded and less probable to be hit or impaired by lightning.
19. Risk Index
According to ‘SP 7’ (1983, National Building Code of India), the risk index for a steel framed building is very low and no protection is required. However, the addition of an air termination and earthing system may improve the degree of protection remarkably at a very small extra cost and may be worthwhile.
Disadvantages of Steel Structures
01. High Maintenance & Capital Cost
When steel structures are exposed to severe or aggressive weather conditions, it may get corroded due to the action of steel with atmospheric oxygen or aggressive environment. For preventing such a problem expensive application of paints is required frequently.
Hence, the maintenance cost of steel may go up, which is a sure concern for a common user. Also, the initial cost of steel structure is higher as compared to concrete/wood structure. More skilled labors are required for making a steel structure as compared to concrete/ wood structure.
02. Susceptibility to Buckling
Because of high strength/weight ratio, steel products are in general slenderer and consequently more susceptible to buckling than reinforced concrete members. As a result, considerable materials may have to be used just to improve the buckling resistance of slender steel items.
03. Fatigue and Fracture
Steel structures are quite susceptible to fatigue. Large variations in tensile strength expose steel elements to excessive tension, which decreases its overall strength. Steel is also responsive to brittle fracture when it loses its ductility. These two adversities increase its chances of buckling, which is typically counterbalanced by adding expensive steel columns that can successfully stiffen the primary structure.
04. Fireproof Treatment
Although steel elements are incombustible up to a temperature, the strength of steel gets highly compromised at the exposure against higher temperatures due to fire or when other materials within a building burn, making them susceptible to buckling.
Moreover, steel is a good conductor of heat, ignites materials in contact and often causes fires, which rapidly spread to other sections of a building. Hence, steel structures may require additional fireproofing treatment.
Steel structures are also provided with fireproof coatings i.e. expanded mineral coatings. Sometimes, steel structures are enclosed in masonry block, gypsum block, gypsum board and clay tiles enclosures that protect them from heat. However, building these enclosures are much expensive and they require additional maintenance continuously.
05. Fire Damage
Steel is, indeed, less flammable than other construction materials i.e. wood etc., and more flammable than concrete if exposed to fire for long. But its strength and endurance can be reduced if exposed against by high temperatures.
In high temperatures, plastic deformation under load occurs, creating large deflections in steel members. Any stresses on main steel member transfer loads to other members, potentially results in collapse.
06. Fabrication Error
Though steel is a versatile material, it is not easy to make field corrections if one or more components do not fit properly. Most of the metal building manufacturers perform adhere to strict quality assurance processes to ensure all parts of a building fit correctly. But in actual it is not possible. One cannot mold it or cut it in desired shape on site once it is fabricated.
According to ‘J. K. McKay‘ (Author of Building Construction), the difference in cost, performance and maintenance between steel and reinforced concrete framed (multi-storey) structure is negligible, and none of these options has any marked advantage over the other. Each building needs separate consideration. Individual analysis will determine the ultimate decision and guidance on the choice of the material.
Scope and utility of using steel products is vast. Steel structure, has many advantages over wooden/RCC structure. From its durability and strength to its environmental benefits, steel structures consistently prove to be a superior choice over the other construction materials.
Over all steel is a versatile building material, which has led to its involvement in nearly every stage of the construction process from framing, floor joists, to arrange or to create roofing materials, etc. Though steel is not recommended for using in the small houses, it is perhaps the only cost-effective solution for large and heavy structures. The utility of steel structure in the construction industry is therefore seamless. Hopefully it will expand more in future.