▲ Home Insurance Building, the world’s first skyscraper (Lifespan: 1885 ~ 1931)

But what about for residential construction? Steel is definitely used to build our houses – wall panels, pipes and all – but are they simply design components? If not, how crucial are they?
In the past, builders did use to prefer wood over steel to frame residential buildings. However, because of its durability, steel is gaining more popularity.
What are some of the strengths of steel for residential construction in functionality as well as aesthetics aspects? What potentials does POSCO see for steel as residential construction materials? POSCO Newsroom reports.

l Steel Beauties around the World

Although wood has been popular as structural materials for residential construction, here are some of the advantages that steel has over wood. Steel has a higher strength to weight ratio than wood, which means steel components are stronger without adding much weight.

This is what makes steel structures stronger than wood, which is very attractive in areas prone to tornadoes, earthquakes, and other natural disasters. Steel is also fire- and termite-resistant, making it more durable than wood. To promote the strength of steel as residential construction materials, the World Steel Association (worldsteel) introduced ten houses as part of its #lovesteel campaign. Here are some of the examples.

(1) Corten House in Belgium
Located in Kontich, Belgium, the house was completed in 2013. The steel used by the firm DMOA House for the Corten House has plenty of assets to fall in love with, for its structural strength, pureness as well as the warm color of rust. The versatility of steel allows it to shape in any way.

▲ Courten House (Photo by: Luc Roymans)

The owner of the Corten House says, “We were especially charmed by its deep rusty red color, which intensifies around sunset. While being a raw material, Corten steel also brings a vivid ambiance. The house combines a unique and contemporary style with warmth and coziness.”

(2) Flip House in San Francisco, USA
Designed by Fougeron Architecture, this 2013 Residential Architect Merit Award winner is a flip of tradition San Francisco home.

▲ Flip House (Photo by: Joe Fletcher)

Like many San Francisco homes, the original house poorly integrated its many levels with each other. Instead of selecting a new site or building a completely new home, the Fougeron Architecture reinvented and remodeled the house to suit the unique needs of a growing family in a dense urban culture. The glass panels that create the undulating curtain walls of the facade fills the rooms with natural light, allowing a great view of San Francisco – the thin steel frame made it possible to contain the glass panels.

(3) Residence at Alibag in Mumbai, India
Situated on a steep hill with Mumbai in the distance, the steel and concrete used in this design defy conventional approaches. The architect chose to deconstruct cuboid that is tilted and suspended over the ground giving the impression of a floating house. With the steel structure, the designers at the Malik Architecture successfully created concrete planes making contact with the ground, while steel floats above it.

▲ Alibag Residenc (Photo by: Malik Architecture)

All in all, using structural steel provided a column-free, and flexible use of interior space. At this residential house in Alibag, structural steel has been used in its purest form, a major aesthetic element in the overall composition.

(4) Kloof Road House in Johanenesburg, South Africa
Located at the foot of a nature reserve in Bedfordview, Johannesburg, black steel is used extensively for the house’s exterior, creating a distinct bland with the soft green colors of the garden and white-washed walls.

▲ Kloof Road House (Photo by: Nico vander House)

Steel and glass are prominent materials used in Kloof Road House and have been uniquely integrated into the design, from the boundary wall all the way into the interior details. The angled columns and steel beams pierce the double volume space. These structural elements were designed to appear sculptural, while the sculptures on display simultaneously compliment the structural components of the building.

(5) Moebius House by Tony Owen Partners
A suburban house overlooking Sydney Harbour, the complex curving structure is made possible by pre-cut steel-framed panels. The design is a good example of ‘liquid architecture’ whereby projects are designed parametrically using 3D modeling software.

▲ Moebius House (Photo by: Tony Owens Partners)

ㅣSteel Houses Made by POSCO

The houses introduced by the worldsteel proved the value of steel as structural material for residential construction, well beyond design components. Nonetheless, one of the major drawbacks to using steel in residential construction is price. It is still challenging to find contractors to build residential homes with steel framing. Compared to wood, steel homes cost about 14 percent more to build and require more time to complete.

The benefits of steel, however, seem too good to ignore. POSCO, who has been well aware of steel’s potential as residential construction material, took on projects to help curb the notion that steel house is expensive.

In 2018, at the heart of Seoul’s Seodaemun district, POSCO built a youth share house Nuri, made of steel, for people who are just starting out in their career. Nuri not only provides a place to nurture young people facing housing insecurity, but also uses five POSCO technologies that are ideal for structural safety, durability and energy saving.

For the construction of Nuri, POSCO used the rust-free and corrosion-resistant PosMAC. In addition, PosART (aka POSCO Artistic Steel) decorates the lobby of the Nuri, symbolizing the young residents’ passion and dream sprouting and springing up there. PosART broke ground and became commercialized last year as Korea’s first high-resolution inkjet print – PosART is also semi-permanent.

▲ PosART at POSCO Steel House, Nuri

With the company’s own steel materials, POSCO also builds and donates steel houses for the underprivileged communities – both POSCO employees and Beyonders (POSCO’s global youth volunteer corps comprised of community-minded university students) actively participate. Ever since the company broke ground for its first steel house in 2009, POSCO donated more than 50 houses to the communities in need.

Steel is also in use as the major source of residential construction material for POSCO’s Steel Village. Just like steel houses above, POSCO’s Steel Village project is also a community-oriented project where POSCO’s technology and materials are put into good use.

Since 2014, POSCO built more than 104 houses – and steel bridges – in Vietnam’s underprivileged communities. This year, POSCO is undertaking the Steel Village Project in Indonesia Cilegon district where POSCO’s integrated steel mill PT.KRAKATAU POSCO is located.

l Steel Buildings Last More Than 100 Years

To sum up, here are some key statistics of steel use in construciton:

▲ Steel use in construction: statistics – sourced from worldsteel and reproduced in POSCO Newsroom

More than 50% of all steel goes into buildings and infrastructure – and the global construction recovery rate for the 100% recyclable steel is at 85%. Not only that, thanks to new high strength steel, building components require 25-50% less material.

Steel buildings last more than 100 years – that’s why steel is one of the major structural materials for so many commercial buildings whilst establishing itself as crucial design components in residential buildings.
The strength of steel as residential construction materials is getting recognition and its use is likely to be expanded. As a steel company, POSCO will continue the journey to promote the potential of steel in a way that can help contribute to the community it serves.

Scientists predict 2018 may be a tumultuous year for earthquakes. (Source: Take Two)

As structural damage is the leading cause of injury and deaths during an earthquake, architects, engineers and builders need to make sure buildings are built with the right materials and design.  

SEE ALSO: What it Takes to Build a Natural-Disaster-Proof House

The Materials

The most dangerous type of earthquakes are ones that trigger horizontal movements, because tall buildings are better at resisting vertical loads than horizontal ones. These ground motions can damage building foundations in a matter of minutes, causing severe injuries and deaths. Building a structure to withstand seismic waves starts with the right materials with the right properties, and steel is by far the most widely used material for building earthquake-resistant buildings.

According to the World Steel Association, ductile buildings are safer as they dissipate energy from seismic waves. A building will typically have ductile parts that can undergo plastic deformations without complete structural failure during an earthquake. Steel is the most common type of material for such parts.

Moreover, due to the law of inertia, the lighter the building, the less force seismic waves will exert on the building. That’s why it’s important, especially for taller buildings, to be made of light and flexible materials such as steel that can “bend” with the movement of earthquakes. On average, multi-story steel buildings are 60 to 70 percent lighter and 10 times stronger than concrete-framed buildings of the same size.

The Design

With steel, builders can add vital designs and reinforcements to keep the structure standing through an earthquake. Here’s some of the most widely-used measures.

Cross braces transfer the force of an earthquake to the ground. (Source: Earthquakes in India)

The structural integrity of buildings can be reinforced with steel cross braces that frame the exterior of a building in an x-shape. Ultimately cross braces can transfer the force of seismic waves back down to the ground, instead of letting the building take the hit. Builders can also reinforce the walls of buildings with additional vertical walls, or shear walls, that add stiffness to the frame of the building, allowing it to resist swaying or horizontal movements.

Base isolators absorb much of the shock of seismic waves. (Source: Embelton)

Base isolation involves separating the building from the foundation so that the isolators to absorb shock from the earthquake. The isolators allow the building to move at a slower pace because they dissolve a large part of the shock. Moment-resisting frames also effectively dissipate energy from floors and roofs to the building’s foundation and the stiff yet flexible frames can change shape during an earthquake. Although more costly, moment-resisting frames enable buildings to withstand an earthquake with excessive horizontal movement.

Putting it into practice with POSCO’s Steel House

In September 2017, Young Bae Kim’s home in Gyeongju province, Korea was hit with a 5.8 magnitude earthquake, just 8.9 km from where the earthquake started. Surprisingly, Kim’s home was unscathed. “I could feel the ground shake, but the house was completely under control.” Kim expressed.

Kim lives in one of the Steel Houses built by POSCO employees who volunteer to build homes and bridges for communities in need. Each Steel House is made with POSCO’s lightweight structural steel known for its durability, fire resistance and vibration resistance. The homes also incorporate PosMAC, a specialized galvanized steel that is 5 to 10 times more corrosion-resistant than standard steel and is more durable and affordable.

POSCO Employees volunteer their time to build steel houses in rural communities.

Because all the Steel Houses survived the Gyeongju earthquake while other homes were damaged, more and more people in Korea are choosing steel for their homes over traditional building materials such as wood and concrete. The same trend can be observed in Japan, where earthquakes are much more frequent. In order to build more earthquake-resistant buildings, steel is still the best solution available.

Cover photo courtesy of CNN.

Iron: Inexpensive Yet Strong, ‘Economically Feasible’ Material 

Steel is one of the most abundant resources. As a result, the cost of steel is indeed very cheap. It only costs approximately 1/3 of its closest alternative, Aluminum, which costs roughly 1700-2000 USD per ton. Furthermore, steel’s price compared to its strength property is significantly lower at 4.4 when compared to other materials such as aluminum alloy at 21.2 and plastic at 11.3. This indicates that steel is cheap despite the material’s outstanding strength. Although directly comparing the costs of steel products to those of similar products made of other materials is meaningless since different materials involve different production process, but it is clear that steel products are cheap yet strong and that steel is relatively more economically feasible when compared to other materials. 

‘From a Needle to a Vessel’, Well-rounded Material with Properties of Handy Procedure, Corrosion-resistance and Durability 

As implied in the phrase ‘From a needle to a vessel’, steel is extensively used in diverse fields. Not to mention the cheap cost of the material, Steel’s mechanical properties, corrosion resistance and machinability allow its flexible application to various industry fields. It comes as no surprise that steel is universally considered as the most important material in engineering and construction industry.

Plastic is often perceived and used as an alternative material to steel for the characteristics alike; plastic has the merit of being easy to process, mechanically durable, pressure-resistant, and heat-resistant due to high softening temperature, pressure and electro-thermal. Despite all the positive aspects, plastic is still considered inferior than steel in terms of the material’s mechanical and chemical properties.

Through Recycling Process, ‘Iron’ is Eco-friendly 

When estimating a certain material’s level of eco-friendliness, recycle availability becomes the standard. In the case of plastic, only 3 ~ 5% of the overall production is recycled. However, due to its simple recycling process, iron stays eco-friendly through high usage of the process.

By reusing the recycled iron, it is possible  to decrease 82% of Carbon Dioxide, 88.9% of nitrogen oxides, and 94.7% of sulfur oxides, compared to directly producing iron from minerals. Therefore, iron scraps are considered as one of the top three ingredients of steel along with iron ore and coke.

Even the production process of iron has less negative effects on nature, compared to the processes of other mineral resources. In order to mine mineral resources, trees and forests need to be cut down to make a tunnel in the area. Prior to the mining, a series of content analyses of an iron ore is held to assess economic feasibility of the site. For gold, 3 grams of gold per 1 ton of raw ore is considered economically feasible. This ‘feasible content’ for Aluminum is 13%, iron 5%, copper 0.8% yet the steel is at astonishing 60%. This means that steel is an ‘eco-friendly’ material in that the mining process does not involve extensive environmental destructions and leaves minimal wastes compared to other natural resources. In other words, more use of steel over other materials helps to save the environment. Environmental destruction due to mining process is inevitable yet the negative impacts could be minimized with more use of steel.

Various Usages in Our Daily Lives

Other than the excellent qualities introduced above, there are many more usages in our daily lives. Human body contains certain amount of iron and it is used in manufacturing products from food container to artificial bone structure. Also, sometimes iron is used in producing another type of metal with improved qualities, such as stainless steel. Known for its non-rusting and robust property, the stainless steel is an alloy of regular steel with reasonable amount of carbon, nickel and chrome. As shown, depending on the type of materials added to the steel, various steel products with many different qualities can be made. Since they alloy of iron or oxides tend to be magnetic, it is widely used in producing computer diskettes, recording tapes, skippers, calling cards and more. We could expect for an enhanced quality of life by further developing the outstanding properties of iron and utilizing them into new products in the future!

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Case Study – Steel House

POSCO has built a steel house ‘Youth Shelter’ to support teenage runaways who are not capable of living an ordinary life due to domestic conflicts or violence. In addition, a senior welfare center called ‘Happy Steel House’ was constituted with the fund raised by POSCO family employees’ 1% share campaign. Including the ‘Happy Steel House’, POSCO’s Steel House construction is now being applied in various social contributions in Korea.

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