Properties of Steel Used in Construction
Steel is a critical material in construction, particularly for reinforced concrete structures. Different types of steel, such as HYSD (High Yield Strength Deformed) bars and TMT (Thermo Mechanically Treated) bars, are used based on their properties and applications. These types of steel are also essential for creating accurate Bar Bending Schedules (BBS).
Types of Steel Used in Construction
Below are the common types of steel used in construction, along with their key properties:
1. HYSD Bars
High Yield Strength Deformed (HYSD) bars are widely used in construction due to their superior mechanical properties compared to mild steel bars.
- High Strength: Higher tensile strength compared to plain mild steel.
- Deformed Surface: Ribbed or twisted surface enhances the bond with concrete.
- Yield Strength: Typically ranges between 415 MPa and 500 MPa.
- Applications: Used in beams, slabs, columns, and foundations.
2. TMT Bars
Thermo Mechanically Treated (TMT) bars are manufactured using a special heat treatment process, making them a popular choice for modern construction.
- High Tensile Strength: TMT bars have a tensile strength of up to 600 MPa.
- Corrosion Resistance: Their manufacturing process provides better resistance to corrosion.
- Flexibility: TMT bars offer excellent ductility, making them suitable for earthquake-resistant structures.
- Applications: Used in bridges, dams, high-rise buildings, and industrial structures.
3. Mild Steel Bars
Mild steel bars have smooth surfaces and are generally used for light reinforcement works.
- Lower Strength: Yield strength of approximately 250 MPa.
- Easy Workability: Easier to cut and bend compared to HYSD and TMT bars.
- Applications: Used for small-scale construction or non-critical structures.
Example of BBS with Steel Types
Consider a beam reinforced with TMT and HYSD bars. The BBS is as follows:
| Bar Mark | Diameter (mm) | Steel Type | Shape | Length of Each Bar (m) | Number of Bars | Total Length (m) | Weight per Meter (kg) | Total Weight (kg) |
|---|---|---|---|---|---|---|---|---|
| 1 | 16 | TMT | Straight | 4.5 | 10 | 45.0 | 1.580 | 71.1 |
| 2 | 12 | HYSD | Stirrups | 1.2 | 20 | 24.0 | 0.888 | 21.312 |
In this example, TMT bars are used for the main reinforcement due to their higher strength, while HYSD bars are used for stirrups to ensure adequate shear resistance.
Conclusion
Understanding the properties of different types of steel is crucial for selecting the right material for construction. TMT and HYSD bars offer superior performance and are commonly used in modern construction, ensuring strength, durability, and safety. Proper knowledge of these materials also helps in creating an accurate and efficient Bar Bending Schedule (BBS).