Table of content for MS Steel Sections used in Construction-
- Why do we use MS Steel sections in construction?
- How MS Steel sections are used in construction?
- How to join MS Steel Sections?
- Types of MS Steel Sections used in Construction.
- Rolling Margin
- MS Steel section weight calculator- Excel Template
Steel is an alloy of iron and carbon. It also contains other metals such as chromium, nickel, copper, molybdenum etc. in small percentages. The % of constituent metals govern the properties of the steel.
The popularity of steel is due to its’ versatile properties. The combination of strength & durability makes steel a viable option for usage in construction as well as for other uses.
India is the largest crude steel producer in the world after China. India had produced 100.3 million tons of crude steel in 2020. The steel production capacity has increased approximately 11 times in the last 30 years (9.5 million tons in 1980).
The finished steel consumption of India stands at 93.43 million tons in FY21.
In this article, we shall discuss the purpose of using steel in the construction, jointing methods for steel sections, common types of steel sections used in the construction and tolerance limit for steel sections’ size i.e., rolling margin. Last but not the least, a free excel template to calculate the weight of steel sections.
Why do we use MS Steel sections in construction?
Mild steel is generally used in construction. It is low carbon steel having 0.05-0.25% carbon. The mild steel has a yield strength of 250 MPa and ultimate strength of 400-550 MPa. The density of mild steel is 7850 kg/m3.
The ability of mild steel to resist higher compression and tension makes it a desirable construction material. However, it has lower strength and higher ductility when compared to its higher carbon alternatives.
There are some reasons for the wide use of MS steel in construction.
- Higher load carrying capacity than concrete. The MS steel carries 10 times more stress when compared to concrete of M25 grade. Hence, the thinner sections are required to carry the same load.
- It takes lesser time for construction. No need for formwork, only shop fabrication, site assembly and erection are done.
- It is easier to fabricate the structure of MS steel due to its’ excellent response to the welding.
- The MS steel sections are easier to connect to each other with welding, riveting or bolting.
- It is easily available in the market.
- The MS steel is a cost-effective construction material.
- The MS steel durable if it is properly maintained and protected from corrosion.
- Good scrap value. It can be easily sold after completing usable life.
- The MS steel can be reused and recycled.
How MS Steel sections are used in construction?
The uses of steel sections are numerous. Some of them are as follows-
- Roof Truss
- Platform & Floor
- Scaffolding pipes
How to join MS Steel Sections?
The steel sections are joined with each other to make a structure. The joints can be welded, riveted or bolted. The joints are designed to transfer the load. All three types of joints are strong enough to keep the structure intact under normal loading conditions.
The rivets used for the rivet joint should conform to IS 1929 & IS 2155. For nuts, bolts and washers, IS 4000 provides the necessary recommendation.
The steel sections are joined by the butt joint, lap joint, T-joint, corner joint and edge joint. All of these sections are named as per the position & orientation of pieces that are joined together either by bolting, riveting or welding.
- Butt Joint- Two Pieces are joined together side by side in the same plane.
- Lap Joint- It is similar to the butt joint except the fact that a piece overlaps over the other.
- T-Joint- It resembles to the “T” hence the name. The pieces are connected perpendicularly over each other.
- Corner Joint- The corner joint is similar to the T-joint but the edge of one piece is attached perpendicularly to the edge of another piece.
- Edge Joint- The two pieces are such joined that their edges are parallel.
Types of MS Steel Sections used in Construction
The construction industry widely uses hot and cold rolled sections. The I-section, L-section, C-section, plain bar and hollow sections are commonly used sections.
- I-Section- It is also called beam section as it is commonly used as beams. It is also used as columns. The Indian standard beam section ISMB is one of the most used sections. The usual sizes are ISMB 100, 200, 250 and 300.
- L-Section- The angle section or L-section is another popular section. It is available under Indian standard as ISA. It is used for bracings, purlins, concrete edge protection etc.
- C-Section- The channel section offers an alternative to I-section for some applications. It resembles the letter C and available in Indian standard as ISMC.
- Plain Bars- The MS steel plain bars are available in the market. They are a cheap alternative to reinforcement bars and used in low importance work due to their poor bond with concrete.
- Hollow Sections- Thehollow sections are available in square and circular cross-sections. They offer good resistance to bending. Circular hollow sections are very common in handrails.
- MS Plate- The plates are sheets of mild steel with thickness of up to 40 mm. They are used for making ducts.
- MS Flat- Thestrips of mild steel are called MS Flats. Their thickness and widths are standardised and available in the market. The common use of flat is in staircase toe-guard, fabrication of grating etc.
- Chequered Plate- A chequered plate is for floor or platform. It has pattern over it that provides protection against slipping.
The MS steel sections used in construction are manufactured by the rolling process. The dyes that roll the steel into a fixed size get wear and tear. Thus, the opening of dye increases hence, larger sections are produced.
Sometimes, due to the accumulation of material on the dye, the opening of dye decreases in size. Hence, smaller cross-sections are produced than the designated sizes.
The difference in the size of a section from its’ actual size is called the rolling margin. Due to the change in dimension, the weight also changes. Therefore, the weight difference can lead to over or underpayment to the vendor and contractor.
IS 1852-1985 (Reaffirmed 2003) specifies tolerance in weight as +-2.5% for structural steel sections (I-section, C-section and L-section). However, the establishment of a rolling margin at the site and rechecking from time to time is always recommended.
To establish the rolling margin at the site, a number of representative samples of unit length (or area) from the site stock are taken. The samples are weighed. The difference in actual weight and the theoretical weight is divided by the theoretical weight and recorded as a percentage. This rolling margin % is then used in calculations for billing.
MS Steel Section Weight Calculator- Excel Template
My love for excel sheets has brought you another template to calculate the unit weight and total weights for MS steel sections used in construction.
The template provides unit weight for chequered plate, ISMB, ISMC, ISA, Grating, MS Flat, MS Plate, MS Pipe, UB and MS Rod.
Instructions to use the excel template-
- Select the section from drop-down list in 1st yellow cell on left-hand side.
- Choose the specification of selected section from another drop-down list in 2nd yellow cell on left hand side.
- The unit weight of the section appears on the right hand-side.
- You can also calculate the total weight of the section by entering the total length or area in the 3rd yellow cell on left-hand side.
You may also like Civilverse’s other related excel templates-
Civil Construction Material Calculator – free excel template.
Construction Labour Planning– free excel template for labour productivity.