023023BUILDING BUILDING SCIENCESCIENCESTEELSTEEL

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Building Science-SteelBuilding Science-Steel

Building Science-SteelBuilding Science-SteelWhat is Steel?Steel, which is an alloy of iron and carbon,

is the most versatile and important engineering and construction material in the world.

Its use influences every aspect of our lives and the built environment

Building Science-SteelBuilding Science-Steelfrom automotive manufacture to construction products

from steel toecaps for protective footwear to refrigerators and washing machines

from cargo ships to the finest scalpel for hospital surgery.

Building Science-SteelBuilding Science-SteelSteel BenefitsThe physical properties of steel, such

as:durability,Flexibilitystrength All offer significant advantages in the material efficiency of a product application.

Building Science-SteelBuilding Science-SteelSteel is one of the most sustainable building materials with unique characteristics that favour its use in the construction industry.

Steel for sustainable development

Steel has many significant advantages with regard to the demands of sustainable development.

Building Science-SteelBuilding Science-Steelconstruction sectorregulation on environmental matters All are becoming increasingly strict,

it is vital to communicate and demonstrate the advantages of steel to:

Buildersspecifier,the authorities (regulatory bodies, in

particular) and educators.

Building Science-SteelBuilding Science-SteelSteel to build fasterThe speed and accuracy of

construction is critical to the creation of building and stakeholder value.

Earlier occupancy means an office owner can begin renting space sooner

a factory owner can start producing products faster and the store operator can bring in sales pounds quicker.

Building Science-SteelBuilding Science-SteelFast construction also has advantages

such as: Lowers financing costs and overhead expenses for construction management services.

Earlier occupancy means an office owner can receive rent and pay back loan quicker.

Building Science-SteelBuilding Science-SteelSteel for earthquake safetyEarthquakes are unpredictable in terms of magnitude, frequency, duration, and location.

Light gauge steel framing is capable of meeting this standard due to its ductility

Building Science-SteelBuilding Science-SteelSteel to optimize spaceReducing storey heights will cut the costs for steel and other building materials.

From an energy-efficiency standpoint,

minimising floor-to-floor heights also helps curb heating and cooling costs.

Building Science-SteelBuilding Science-SteelRunning mechanical systems through

web openings is one solution for minimising building height.

Another way is integrating floor beams into interior walls or partitions.

In some cases, it is possible to limit the depth of beams by choosing a member size that is shallower, though heavier, yet still offers the same required strength.

Building Science-SteelBuilding Science-SteelSteel for flexibilityBuilding owners often are faced with the challenge of modifying an existing space to meet changing needs

perhaps adding a new staircaseelevator or column-free space,or even raising or lowering a ceiling.

Building Science-SteelBuilding Science-SteelChanges may also be necessary to

comply with legislation such as:the need to provide access for the disabled.

Steel is the only material that allows the strength of a structure to be increased economically once it is built.

Building Science-SteelBuilding Science-SteelWHY USE STAINLESS STEEL?Stainless steel has been used with

success by the construction industry throughout the UK and Europe for over seventy years.

Its use has increased rapidly in recent times as the benefits of stainless steel over traditional materials have become more widely recognised.

Building Science-SteelBuilding Science-SteelStainless steel offers many advantages

to the specifier:Excellent corrosion resistanceHigh ductility and strengthNon-magnetic (Austenitic only)Excellent high and low temperature properties

Building Science-SteelBuilding Science-SteelResistance to unsightly stainingLife-cycle costing benefitsAesthetic surface finishLife-cycle costingThe maintenance-free life and

confirmed integrity of stainless steel mean that no costly remedial or refurbishment measures are required during the life of the structure.

Building Science-SteelBuilding Science-Steel

Use of stainless steel

Building Science-SteelBuilding Science-Steel

Stainless steel lintel

Building ScienceBuilding ScienceCreep Is the tendency of a solid material to slowly move or deform permanently under the influence of stresses.

It occurs as a result of long term exposure to levels of stress that are below the yield strength of the material.

Building ScienceBuilding ScienceCreep is more severe in materials that

are subjected to heat for long periods, and near the melting point.

Creep always increases with temperature.

Creep is a deformation mechanism that may or may not constitute a failure mode.

Moderate creep in concrete is sometimes welcomed because it relieves tensile stresses that might otherwise lead to cracking.

Building ScienceBuilding ScienceStress RuptureStress rupture testing is similar to

creep testing except that the stresses used are higher than in a creep test. 

Stress rupture testing is always done until failure of the material.

In creep testing the main goal is to determine the minimum creep rate in stage II. 

Building ScienceBuilding ScienceOnce a designer knows the materials will creep and has accounted for this deformation a primary goal is to avoid failure of the component.

Building Science-SteelBuilding Science-SteelWhat is Corrosion?Corrosion is the decaying or destruction of a material caused by the environment in which the material resides.

For example, steel rusts when immersed in seawater.

Building ScienceBuilding ScienceThe process of corrosion requires

four elements: an anode,a cathode,an electrolyteand a metallic path. Corrosion is a natural process

Building ScienceBuilding ScienceCorrosion cannot be prevented, but intervention with the correct measures can control it.

Without intervention, corrosion progresses and becomes damaging.

Building Science-SteelBuilding Science-SteelForms of CorrosionCorrosion takes many different forms.

The type of materialthe environment in which the material resides

the length of exposure to the environment all contribute to determine the form.

Building Science-SteelBuilding Science-SteelSome of the more common forms of corrosion are defined below."General Corrosion" is also known as "Uniform Corrosion"

Building Science-SteelBuilding Science-SteelGalvanic CorrosionGalvanic corrosion occurs in the presence of an electrolyte such as seawater when dissimilar types of metals join together.

Most metals have different electrical potentials.

Building Science-SteelBuilding Science-SteelWhen connected electrically and placed in an electrolyte, the more active metal becomes the anode because it has more negative potential

As a result-corrodes faster than if it were alone in the environment.

Building ScienceBuilding ScienceGalvanic Series (For Seawater)The Galvanic Series lists types of

metals, platinum being the most noble (least active) metal

least susceptible to corrosion.If two metals need to be placed

together in seawater, select metals from the list that are as close together as practicable to avoid corrosion.

Building ScienceBuilding ScienceTo reduce galvanic corrosion use as

close as possible Magnesium and its alloysZincAluminium and its alloysCadmiumMild Steel and IronCast Iron13% Chromium stainless steel (active)

Building ScienceBuilding Science18-8 Austenitic stainless steel (active)

LeadTinNickel (active)Inconel (active)BrassesCopperBronze

Building ScienceBuilding ScienceCupronickel alloysMonelNickelInconel (passive)Iron-chromium alloys (passive)

18-8 stainless steels (passive)Hastelloy C

Building ScienceBuilding ScienceSilverTitaniumGraphiteGoldPlatinum

Building ScienceBuilding ScienceCorrosion in Concrete

Building ScienceBuilding ScienceTo support concrete structures, common construction practice includes:

carbon steel reinforcing rodscable, and wires inside the structure.

The steel that resides within the concrete structure is where corrosion can develop.

Building ScienceBuilding ScienceSome reasons corrosion may develop are poor construction and an unfavourable environment, such as:

environments that favour impact

Abrasionchemical attackfreeze-thaw cycles

Building ScienceBuilding ScienceCorrosion in steel is an electrochemical process.

An anode, a cathode, a metallic path and an electrolyte must present.

Oxidation occurs at the anode and reduction occurs at the cathode.

Building ScienceBuilding ScienceConcrete contains an alkaline environment that provides protection against corrosion.

The concrete reacts with the steel and forms a film that passivates and protects the steel.

However, chloride ions can weaken the film.

Building ScienceBuilding ScienceConcrete can absorb chloride through admixtures, de-icing salts, chemicals, seawater or contamination of the concrete mix.

If oxygen and humidity are present, the corrosion process will begin.