Some Issues in the Usage of Fe- 500 or Higher Grade TMT Steel Bars in Residential Buildings
Some contractors report a tendency among few design Engineers to specify Fe-500 or higher-grade steel in residential buildings due to its high strength. Customers are advised that if they use Fe 500 or higher-grade steel in building construction, that would help in decreasing the quantity of steel used and reduce the column sizes.
At other side Fe 500 grade steel could pose quite a few site-specific issues during construction, especially for small builders. Considering the reported failures and problems with grade Fe-500 or higher, it is advisable to use Fe 415 in residential and commercial buildings and Fe500 could be used only when the entire design is made according to that grade. This is explained below;
Usually, Concrete, a mixture of cement, sand and aggregate, is considered by far as the most stable of building compounds. But it has negatives also: low tensile strength and ductility. This means that concrete’s ability to stretch and to withstand pressure at an angle without breaking is very less.
Here Steel has its role. Steel in the form of bars has great tensile strength and ductility. It can reinforce concrete. Thus, the quality of steel has an important role in deciding the quality of concrete. Quest for better material has produced various kinds of steel bars with qualities that make concrete more stable. It started with mild steel Plain bars, evolved through deformed plain bars and then came Cold Twisted Steel Bars (TOR steel). Now the Market is dominated by various grades of TMT.
Fe 415 TMT bars became the most commonly used steel grade in construction of houses in the state as it is easier to produce the desired strength equivalence of CTD bars ( Cold Twisted Bars) through the TMT process than through the conventional CTD bar production process apart from the other advantages of TMT over CTD.
Higher grades of TMT steel- Fe 500 and above –may be used in high rise buildings. This is because using Fe 415 steel will require a larger number of rebars to provide the required strength. That would increase the size of the columns. This is a serious concern at a time when space is at a premium else why should one go for high rises.
Fe 500 is produced using the same TMT process that is used to produce Fe 415. The beauty of the TMT process is that it can produce different grades of steel by making slight changes in the process. If the steel is quenched a little more, the outer martensite layer that provides the high strength to the steel rebar becomes thicker at the expense of the soft inner core that endows it with ductility. This is exactly what happens in Fe 500 grade TMT steel.
Some contractors report a tendency among few design Engineers to specify Fe-500 or higher-grade steel in residential buildings due to its high strength. Customers are advised that if they use Fe 500 or higher-grade steel in building construction, that would help in decreasing the quantity of steel used and reduce the column sizes.
At other side Fe 500 grade steel could pose quite a few site-specific issues during construction, especially for small builders. Considering the reported failures and problems with grade Fe-500 or higher, it is advisable to use Fe 415 in residential and commercial buildings and Fe500 could be used only when the entire design is made according to that grade. This is explained below;
Usually, Concrete, a mixture of cement, sand and aggregate, is considered by far as the most stable of building compounds. But it has negatives also: low tensile strength and ductility. This means that concrete’s ability to stretch and to withstand pressure at an angle without breaking is very less.
Here Steel has its role. Steel in the form of bars has great tensile strength and ductility. It can reinforce concrete. Thus, the quality of steel has an important role in deciding the quality of concrete. Quest for better material has produced various kinds of steel bars with qualities that make concrete more stable. It started with mild steel Plain bars, evolved through deformed plain bars and then came Cold Twisted Steel Bars (TOR steel). Now the Market is dominated by various grades of TMT.
Fe 415 TMT bars became the most commonly used steel grade in construction of houses in the state as it is easier to produce the desired strength equivalence of CTD bars ( Cold Twisted Bars) through the TMT process than through the conventional CTD bar production process apart from the other advantages of TMT over CTD.
Higher grades of TMT steel- Fe 500 and above –may be used in high rise buildings. This is because using Fe 415 steel will require a larger number of rebars to provide the required strength. That would increase the size of the columns. This is a serious concern at a time when space is at a premium else why should one go for high rises.
Fe 500 is produced using the same TMT process that is used to produce Fe 415. The beauty of the TMT process is that it can produce different grades of steel by making slight changes in the process. If the steel is quenched a little more, the outer martensite layer that provides the high strength to the steel rebar becomes thicker at the expense of the soft inner core that endows it with ductility. This is exactly what happens in Fe 500 grade TMT steel.
