What Is a Grade Beam?
Grade Beam is a beam that is built at Grade level (earth level) mostly used to buildings with piles and to connect pile caps to each other. Grade Beams are reinforced concrete members which are constructed to act as horizontal ties between footings or pile caps.
Its main function is to transmit the load from a bearing wall into spaced foundations such as pile caps or caissons. These types of beams generally used when soil bearing capacity is less than the anticipated design loads.
It may have designed to either directly rests on the soil or above the soil spans between piles. In case, when it is required to extent foundation deep into soil the grade beam would be the right choice.
It is not the same as wall footing, as the grade beam is designed for bending and typically spans between pile caps or caissons, while a wall footing bears on soil and directly transfers the weight of the wall to foundation soil.
Also, it is not the same as strap footing, as the grade beam is reinforced to distribute the weight of a wall to separate foundations, while a strap beam is utilized to redistribute the weight of a column between footings.
It can be used as a combination with spread footing, in a case with large moments from lateral loads, in order to reduce the size of each spread footing.
What Is Grade Beam Foundation?
The Grade Beam Foundation is used to transfer all superstructure load to subsoil strata safely.
The depth and size of the beam depending on the intensity of load coming and the bearing capacity of foundation soil on the construction site.
The grade beam depth should be kept at a minimum of up to 150. Grade beams are stronger compare to plinth beams. They also carry the load of the above masonry walls.
Concrete consumption in grade beam foundation is less compared to the conventional foundation. The major disadvantage of using a grade beam foundation is that it cannot allow the construction of the basement.
The reinforcement used for the grade beam is a minimum of 3 bars of 10 mm diameter at the top and bottom of the beam.
Grade Beam Construction Process
Following are the steps involved in the construction process of grade beam,
#1. Preparation and Excavation for Grade Beam
First of all preparation and excavation for grade beams should be done. Excavation of trenches is executed for the beams on the basis of their level. The beams can be constructed on the ground directly and in this case, the ground surface is leveled and prepared.
#2. Install a Framework for Grade Beams
After the preparation and excavation are finished, then according to the dimensions of the beam forms are placed. If we have constructed these beams on the ground, then the bottom of the forms is placed earlier to its sides.
The reinforcement cage is kept on the flat soling brick before we fix side shuttering. The construction of the framework is the same as that of conventional beams when the grade beam is constructed above the ground. Hence, we must place shutters for the bottom and both sides of the grade beam.
After the finalization of the beam framework, the designated grade beam dimensions should be supplied which should contain enough reinforcement cover.
#3. Reinforcement Placement for the Grade Beam
The reinforcement for the grade beam is placed in as per structural drawing. The reinforcement detailing is provided in structural drawings like the size and number of longitudinal reinforcements and its required length, number, and spacing of stirrups.
The number and size of the top, bottom, and extra reinforcements, lap length and placement, spacers, hooks, and clear reinforcement cover must be checked.
#4. Pouring of Concrete for Grade Beam
At last, concrete is poured into the grade beam. A ready mix concrete or on-site machine-mixed concrete both can be used for concreting work. The side support of the grade beam can be 24 hours after pouring concrete. But, bottom formwork should be removed only after concrete gains its strength.
Depending upon the time span of the beam, we can determine the time duration for removing the bottom shutter.
Read More: Standard Height Of Window From Floor Level
Advantages of Grade Beams
1. Forms Easily
This beams are constructed in any size and shapes. So, Grade beams are flexible in nature.
2. Excellent Support for Both Concrete and Soil
This beams are capability to support both the soil before the pour and the concrete during the pour.
3. Easily Penetrated
They can be easily allows the penetration other materials such as rebars, conduit, pipes, or dowels.
4. Less Excavation is required
It installation requires less excavation work that saves time and money.
5. Saves Time and Money
It required less time to construction and less labour cost, hence saves both time and money.
FAQs: Grade Beam
Grade Beam is a beam which is built at earth level mostly used to buildings with piles and to connect pile caps to each other or it can also be explained as reinforced concrete members which are constructed to act as horizontal ties between footings or pile caps.
What are advantages of Grade Beams?
1. These beams are constructed in any size and shape. So, Grade beams are flexible in nature.
2. These beams are capable to support both the soil before the pour and the concrete during the pour.
3. They can easily allow the penetration of other materials such as rebars, conduits, pipes, or dowels.
4. It installation requires less excavation work that saves time and money
Are grade beams necessary?
The necessity of grade beams is not to support significant structural loads directly however it is required to the extent the foundation deep into the soil. The grade beam is reinforced to distribute the weight of a wall to separate foundations and can be used as a combination with spread footing.
Grade beam also called foundation beam. It is a beam that is built at earth level mostly used to buildings with piles and to connect pile caps to each other or it can also be explained as reinforced concrete members which are constructed to act as horizontal ties between footings or pile caps.
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