Presented by:
M.SAHITYA

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FIRE RESISTANCE REINFORCEMENT
Four decades and 12 moonwalks later, the technology still exists in new, advanced products. In 1999, Houston-based International Paint, LLC, acquired the Chartek fireproofing brand. The company’s latest product derived from Chartek technology is coined Interchar and geared toward making America’s high-rise buildings and public structures safer.
Fabrication shop application of Interchar fireproofing material to structural steel beams. Since Interchar is typically applied at a thickness between 1 and 8 millimeters, it does not impact the overall shape of the steel. This means architects and building planners can still explore intricate and innovate architectural designs.
According to Craig Scott, International Paint’s director of fire and infrastructures, the new-construction industry has been forced to reevaluate traditional methods of fire protection in commercial infrastructures. This includes everything from building codes to structural design issues and the less-durable fireproofing materials currently specified for commercial steel structures.
Although steel does not burn, it loses strength in a fire, which can lead to a structural failure. Above 500 °F, steel starts to lose its structural integrity, and at 600 °F, steel loses 75 percent of its strength, according to International Paint. Interchar and other Chartek fireproofing materials swell to provide a tough and stable insulating layer over the steel to protect it.
An Interchar coating is typically applied at a thickness between 1 and 8 millimeters, so it does not impact the overall shape of the steel. Because this is a thin layering process, architects and building planners can still explore intricate and innovate architectural designs, especially when the steel is exposed. According to the company, Interchar’s aesthetic versatility is a unique characteristic for commercial construction that previous Chartek products could not match.
Interchar offers fast cure times, superior adhesion to steel surfaces, and a strong, durable barrier to the steel beam underneath. Altogether, Interchar provides up to 4 hours of fire protection and helps prevent steel infrastructures from collapsing prematurely, in turn, giving building occupants more time to evacuate safely.
The technology is also made to be applied offsite, so that all of the materials that require fireproofing are ready before they are delivered to the construction site. Many benefits stem from the offsite application process: a controlled environment is used to ensure the appropriate thickness, as under- or over-coating could negatively affect Interchar’s function; it saves time and money, since scaffolding and the sealing off of areas during spraying are not involved; and it does not disrupt the work of other contractors or cause project delays.
In addition to fire protection, Interchar is ideally suited for corrosion protection, in structural steel facilities as varied as office buildings, hospitals, stadiums, shopping malls, hotels, airports, schools, power stations, and industrial complexes.
“This is a technology that has come of age,” noted Scott. “The human and economic costs of fire damage can be significantly reduced by the use of a fireproofing system that can address any emergency fire event.”
 Now-a-days the main problem faced by an Engineer is to design a structure against fire.
 This is a typical test to an engineer where he has to use all his skills to design the structure against fire.
 The fundamentals materials of construction are affected by fire.
 For example above 500ºF steel starts to lose its structural integrity. At 6ooºF it loses 75% of its strength.
 At high temperatures hydrated cement in concrete gradually dehydrates-which results in reduction of strength and modulus of elasticity.
Horizontal Assembles :
 Horizontal Assembles such as floors, ceilings and
roofs are tested for fire exposure from the underside only.
This is because the fire in the compartment below presents the most severe threat during fire mishaps.
Vertical Assembles :
 Vertical Assembles such as partitions have to be tested for fire resistance equally form each side since a fire could develop in either side of the partition.
Increasing Blast and fire resistance:
 Thermal radiation travels in a straight line from its source, any solid opaque material will shield against thermal energy.
 Combustibles will ignite when the thermal energy they absorb reaches the ignition threshold.
 Mostly light colours and shiny surfaces are preferred as they reflect a great deal of thermal radiation.
Ventilation;
 When a fire reaches a stage where there is full involvement of the combustibles within a compartment (known as flashover), the intensity of the heat in the hot smoke layer will cause glazing and non-fire resisting facades to fail, allowing hot gases to escape.
Types Of Concrete Filling
Plain Concrete
 The fire resistance of columns filled with plane concrete is limited between 1-2 hours.
 Fire resistance of longer than 1 hour can be achieved by reducing the load levels
 One cautionary note is that the fire resistance of these columns is very sensitive to eccentric loads, i.e., where loads act away from the longitudinal axis.
Steel fibre reinforced concrete:
 The fire resistance of steel columns can be improved significantly by filling them with steel-fibre-reinforced concrete instead of plain concrete.
 The presence of steel fibre about 2% by mass, reduces cracking in the concrete.
 This contributes to the compressive strength at elevated temperatures thus preventing premature failure of the concrete core.
Bar reinforced concrete:
 Columns filled with bar reinforced concrete offer many of the same advantages of columns filled with steel-fibre-reinforced concrete.
 They are however more expensive because of the labour involved in placing the reinforcing bars.
 They are also more difficult to work with in confined spaces with regard to achieving sufficient concrete coverage of the reinforcing bars.
Passive fire protection materials :
 Boards
 Sprays
 Thin film intomescent coating
 Flexible/blanket system
 Concrete encasement and other traditional systems
Fiber reinforced material:
 The building regulations do not allow for the conventional steelwork temperature to exceed 3500 Celsius.
 Because the conventional carbon steel reduces its 0.2% proof stress at 350°C to 2/3 of its specified values at ambient temperature.
 This requirement generally leads to massive amounts of fire protection which is very costly.