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By
Sourav Dutta
Manager-Civil
We generally designate stirrups by its external dimensions. For example, a 250mm x 300mm stirrup has the 250mm and 300mm dimensions in perpendicular directions as shown in Fig 1.
Now a stirrup has 2 bends, types of which are shown in Fig 1 and Fig 4. Guideline of minimum bend length is as per Cl.3.8 of BIS2502 (shown in Fig 3).
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By
Sourav Dutta
Manager-Civil
Brand embossing
On rebar pieces, different items are encrypted in the following manner:
Here, X = Dia of rebar in mm, eg, 20
ABCD = Brand of rebar, eg, TATA TISCON / SAIL / JSPL etc
Y = Yield stress of rebar, eg, 500 indicates Fe500 with yield stress=500 Mpa
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By
Sourav Dutta
Manager-Civil
Design and construction:
The design and construction of formwork should take account of safety and of the surface finish required. The formwork should be sufficiently rigid and tight to prevent loss of grout or mortar from the fresh concrete, during its placing and construction.
Formwork and its supports should maintain their correct position and be to correct shape and profile so that the final concrete structure is within the limits of the dimensional tolerances specified. They should be designed to withstand the worst combination of self-weight, reinforcement weight, wet concrete weight, concrete pressure, and construction and wind loads, together with all incidental dynamic effects caused by placing, vibrating and compacting the concrete.
By
Sourav Dutta
Manager-Civil
Common Hazards/issues normally countered at all construction sites:
Human error in rebar fabrication (manual).
Fig 1 : Incorrect bend
Compromise with safety and quality.
Fig 2 : Safety and Quality issues upon using rebar cutter
Procurement schedule delays affecting site progress, and thereby delaying project completion.
Inventory management. Capital locked in inventory.
Fig 3 : Lack of space at site affects storage/procurement
Rebar pilferage.
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By
Sourav Dutta
Manager-Civil
The first version of BIS 1786 came out in 1985 when in Cl.5.1, the code suggested the nominal sizes as shown below:
Fig 1 (s) : BIS1786-1985 and the relevant clause
The next version of the code BIS 1786 was introduced in 2008, where nominal sizes were rationalized and nominal sizes 7 mm, 18 mm, 22 mm, 45 mm and 50 mm had been removed. In Cl. 6.1, the code had suggested the nominal sizes as shown below:
By
Sourav Dutta
Manager-Civil
The first version of BIS 1786 came out in 1985 where in Cl.1.1, the code had put the detailed physical and chemical properties, testing procedures of following strength grades of HYSD (High Yield Strength Deformed) bars/wires as shown below:
Fig 1 (s) : BIS1786-1985 and the relevant clause
The next version of the code BIS 1786 was introduced in 2008, where new strength grade Fe600 had been introduced. Also, two categories based on elongation for each grade except Fe600 had also been introduced. Thus in Cl.1.1, the code had put the detailed physical and chemical properties, testing procedures of following strength grades of HYSD (High Yield Strength Deformed) bars/wires as shown below:
By
Sourav Dutta
Manager-Civil
It is very clear that metro cities like Mumbai, Kolkata, Delhi and Bengaluru are having increasing development, with tier-II cities also coming up in competition, leading to large land/plot size unavailability. Accommodating increasing population will require the FSI (Floor-space index) / FAR (Floor-area ratio) to be higher.
Fig 1 : High-Rise Canvas over the world now-a-days
By
Sourav Dutta
Manager-Civil
There are a number of ways in which the superstructure can be built. In areas where average to good quality bricks are available, the walls of houses for two to three storeyed constructions can be built out of bricks with the slabs, lintels, chajja etc. in reinforced concrete. Such construction is supported entirely on load bearing brick walls (Fig 1), foundation of which ultimately transfers the building load to underneath soil.
Fig 1: Load Bearing Construction on brick
Fig 2: RCC framed construction
By
Sourav Dutta
Manager-Civil
What is Foundation?
Any structure can be divided into 2 parts:
1. Superstructure: Part of structure above Ground level (GL)
2. Substructure/ Foundation: Part of structure below GL
Components of foundation:
Typically there are 3 components of foundation: (i) Footing, (ii) Column, (iii) Tie beam (refer to picture below)
What is a footing?
Footing is that part of substructure that ultimately transfers the load (dead/live/wind/seismic) to the supporting soil in such a way that the safe load bearing capacity of soil is not exceeded (refer to table 1 for estimation of the safe load bearing capacity of the soil). Footing is a structure constructed in brick work masonry or RCC (refer to figure 1) under the base of a wall or RCC column for distributing the load over a large area.
By
Sourav Dutta
Manager-Civil
What is slab?
A RCC (Reinforced Cement Concrete) slab is the most common structural element of any type of building. Horizontal slabs, typically between 4 and 20 inches (100 and 500 millimeters) thick, are most often used to construct floors and ceilings.Here discussion on “flat slab” has not been considered.
Typical loads to be considered for slab design
(i) Dead load: Any permanent load acting on the slab e.g. self-weight of slab, weight of floor finish & plaster
(ii) Live Load: Any non-permanent or moving load e.g. weight of occupants, furniture, and partitionon the slab
(iii) Snow load (if any)
Note: Earthquake and Wind loads are not considered in the design of slabs.
