Updated: Dec 16, 2022
For many years steel has been a necessary component of all kinds of buildings. Its distinctiveness comes from the way it strengthens the concrete, preventing the building structure from rust or other natural disasters like earthquakes from causing quick wear and tear.
Steel bars come in a variety of varieties and classifications. The characteristics and types of steel bars typically vary based on geographic and environmental considerations. A lot of TOR steel was utilized up until the 1990s. Later, TMT bars with their greater ductility and other attributes slowly took over the market.
TMT BAR AND TOR STEEL
The 'Toristeg Steel Corporation' of Luxembourg is known by the brand name TOR. The Frenchman named TOR who transported 1,000 lbs. of steel across a boat is the source of the word "TOR." Later, it came to be associated with steel bars that had been cold-twisted and deformed (CTD). TOR steel, a high adherence steel, was one of the best grades of steel used in concrete reinforcements for a while between the 1970s and 1990s. TOR steel, which was created from mild steel billets with a small amount of carbon, had the highest tensile stress at the time. The surface distortion caused by the steel's twisting after elongation is what gave the material its high elasticity value. This eventually led to residual stress, which made TOR steel vulnerable to corrosion.
In terms of CIVIL ENGINEERING, TMT (stands for Thermo Mechanically Treated) bar, also known as Reinforcing Bar or Rebar, is referred to as a high-strength reinforcement bar with a hard outer core and soft inner core. TMT bars have repeatedly shown themselves to be incredibly viable for reinforcing concrete constructions since their introduction. TMT bars are a common tensioning tool used nowadays to reinforce concrete and assist to withstand compressive stresses.
TMT (Thermo Mechanically Treated) Steel Bars are perfect for building earthquake-resistant structures because of their high strength, solid construction, and robust appearance. They also can provide better reinforcement to any concrete structure. They provide the ideal mix between hardness and flexibility, which helps to minimize the consequences of any damages caused by seismic events (Elongation). They are stronger than mild steel in terms of tensile strength, yield strength, flexibility, and ductility.
COMPARISON OF TMT BAR AND TOR STEEL:
TENSILE STRENGTH: When compared to TOR steel, TMT bars have better yield-strength values. Using TMT bars will result in using less steel, but using TOR steel leads to using 20% more steel, for an applied load on the structural member. For instance, if a project requires 200 tons of steel overall and uses TMT bars, the same project would require 240 tons of steel total and use TOR steel. Using TMT bars would therefore result in a significant 40 tons of steel savings.
DUCTILITY: The ability of a material or structural component to deform, without collapsing, even after achieving the failure load, is referred to as ductility. TMT bars can safeguard construction structures from rupture and structural collapse since they are more ductile than TOR steel. TMT bars can also add 20% more strength to a building structure thanks to their remarkable strength. What's more, it was all constructed using the same quantity of steel that was required to make standard steel bars.
ELONGATION: The ability of a material to elongate before failing is referred to as elongation. The ductility of a steel bar is greatly influenced by its yield strain/deformation; the higher the elongation, the greater the ductility. Additionally, the likelihood of harm to the construction structure will decrease the higher the percentage of elongation. Unlike TOR Steel, TMT bars may extend in a way that makes construction projects robust and flexible, and well-insured against the threats of natural calamities, such as earthquakes and so forth.
BENDABILITY: Steel bars must be able to be bent into the correct shape for applications like the end-connection of beam-column joints. Although TMT bars and TOR steel both have a solid track record for being bendable, TMT bars have greater elasticity because of their soft inner core, which enables them to bend more and take on a variety of shapes. TMT bars also have greater bending and rebinding characteristics due to their excellent elasticity. Since they can be twisted and molded into any shape during a construction project, they are the simplest materials to handle. The greater bendability of TMT bars helps to build structures and maintain their strength and stability even in the face of hazards like natural disasters.
WELDABILITY: When compared to TOR steel, TMT bars with low carbon content are far more weldable. TMT bars are an excellent option for hassle-free welding tasks because of their low-carbon composition. TMT bars are also simpler to use for construction because they don't need any pre- or post-welding treatments. As a result, architects and construction designers can develop inventive constructions without sacrificing the TMT bars' quality or strength in any manner.
DURABILITY: The primary factor determining the construction structure's durability is resistance to corrosion of steel bars. The chemical makeup of steel bars affects this resistance. In comparison to TMT bars that do not undergo the twisting and stretching procedure, the residual strain in TOR steel starts the corrosion process more quickly. TMT bars maintain their strong corrosion resistance as a result of their production and raw material processing processes. The TMT bars can be submerged in water for an extended time period without experiencing any negative effects during any building operation. Traditional bars are still susceptible to rust since they lack the TMT bars' anti-corrosive qualities.
SEISMIC-RESISTANT: During an earthquake, a building's structure is subjected to cyclic or recurrent loading. Fatigue is the term used to describe the process of failure under repeated loading. TMT bars are more durable and hardy by nature than TOR steel. Initially strong and durable, TOR steel later exhibits a softening tendency that leaves it susceptible to earthquake shocks. TMT bars, on the other hand, can strengthen the tensile strength of building structures thanks to their superior concrete bond and soft ferrite-pearlite core. This subsequently makes it possible for them to absorb more of the energy released during an earthquake and maintain the durability of building structures.
RUST RESISTANT: Corrosion is the cause of failure in any reinforced concrete. Because the concrete contains a lot of chloride ions, TOR steel corrodes in it. TMT bars, on the other hand, are appropriate for construction projects in humid and coastal environments because of their extremely superior rust and corrosion resistance brought about by their thermo-mechanical treatment.
FIRE-RESISTANT: TOR steel has poor thermal stability, making it fire-resistant. TMT bars, on the other hand, can maintain more than 80% of the ambient temperature yield strength at 300° thanks to their better thermal stability. This aids in keeping the buildings secure and safe during fire catastrophes.
FLEXIBILITY: TMT bars are far more flexible than TOR steel, which enables them to withstand high temperatures and humidity conditions. Furthermore, they maintain their integrity even after being bent and rotated 180 degrees.
BONDING: TMT bars adhere to cement better than TOR steel does. This is made feasible by the TMT bars' surface ribs, which span their whole length and have a greater bonding strength. TMT bars' excellent bonding qualities, combined with their superior strength, enable them to forge a robust framework with concrete or cement, enhancing the construction structures' durability and strength.
TMT bars don't experience any physical deformations, hence they are also free of torsional stress. Therefore, the likelihood of surface flaws is very low. In comparison to TOR steel, TMT bars are less susceptible to damaging oxidation, such as corrosion, because of a reduction in surface imperfections.
In addition, TMT bars are less expensive than TOR steel. They do not undergo further hardening procedures like TOR steel, which is why. As a result, less energy and money are used in the deformation operations. In addition, TMT bars employ 8-11% more steel than TOR steel and extend the life of construction projects because they do not react with the concrete to develop rust, which takes up more space and causes fissures in the concrete.
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