This is Structures Explained, and in this article, we are going to discuss typical Beam Reinforcement (Reinforcement Details of Beam)
Reinforcement Details of Beam
Beam reinforcements is an essential part of a concrete beam. It resists tension forces, increases the compression capacity, enhances ductility and reduces long-term deflections in the concrete.
Additionally, reinforcement prevents cracking of concrete due to shear stresses, shrinkage and temperature stresses.
First, we will see the reinforcement distribution in a single span beam and later we will have a look at multi-span or continuous beams.
Single Span Beam Reinforcement
Bottom Reinforcement of Beam
In a single span beam first, we have is bottom reinforcement, which resists the beam from bending stresses.
|Bottom Reinforcement of Beam
They also resist the tension cracks which occur at bottom of the beam, since concrete is weak in tension.
Bottom Reinforcement of Beam run from column to column and have a 90-degree hook at the ends to provide sufficient anchorage.
In case, if additional reinforcement is required by design, they are provided as the second layer above the bottom layer.
If more additional reinforcement is required, they are added in a similar way in the third layer and so on.
Top Reinforcement of Beam
Top Reinforcement of Beam which runs from column to column and has a 90-degree hook with sufficient anchorage at the ends.
|Top Reinforcement of Beam
Top reinforcement also resists the bending stresses produced at the supports.
In case if additional reinforcement is required by design, they are provided as the second layer below the top layer and are extended by one-fourth of span length from the face of a column or as required by design.
Next, we are looking at side face reinforcement.
Side Face Reinforcement of Beam
Side Face Reinforcement of Beam is generally provided to deep beams which have depth higher than 900 mm or 36 inches.
This value of depth differs from code to code.
Side face reinforcement runs along the sides of the beam and resists the crack width in the tension zone of the concrete section.
They also resist the torsional forces and resist 45-degree crack produced due to torsion. Side face reinforcement also takes part in resisting axial forces along the beam.
Additionally, side face bars avoid torsional buckling in deep beams and improve ductility.
These bars are provided equally on both faces of the beam
Stirrups || Transverse Reinforcement
Next, we have is stirrups or transverse reinforcement which resist the shear stresses in the beam and hold the longitudinal reinforcement in place.
Stirrups prevent the shear, flexural and torsional cracks which occur at 45 degrees to the main axis of the beam.
Stirrups also add to the shear strength of concrete. Stirrups are closely placed near the supports of the beam as shear force is maximum near supports.
The closely placed stirrups must be spread a minimum distance of 2 times the depth of the beam, but if required by design, closely spaced stirrups may be distributed along the whole length of the beam.
Classification of Stirrups
Stirrups can be classified based on the number of legs they have.
They can be single-legged, 2 legged, 4 legged and so on.
Based on the loops, stirrup can be open looped or closed looped.
Lastly, based on hook angle, hooks can be180-degree, 135-degree or 90-degree as per design requirements.
This ends our Single span beam reinforcement.
Multi-Span or Continuous Beam Reinforcement
Next, we will have a look at multi-span or continuous beam Reinforcement arrangement with a cantilever at the end.
In multi-span or continuous beam, we have a similar kind of arrangement for bottom reinforcement, top reinforcement, side face reinforcement and stirrups as in single-span beam except for the intermediate junctions, where the top and bottom reinforcement are extended in adjacent spans.
All the extensions are governed by design but typically the extra top bars are extended to one-fourth of the span length in the adjacent beam.
For the Cantilever beam, the top and bottom bars from the adjacent span are continued till the end of the cantilever.
Here, the stirrups are placed closer spacing throughout the Cantilever portion.
That’s it for this article guys. More such article on reinforcement will follow this blog, so do follow by email or follow the Civil Experience blog to get notified every time we upload a new article. Also check out other related uploads on the Civil Experience Blog. See you in the next one.
FAQ 1: type of Reinforcement Details of Beam?
1. Single Span Beam Reinforcement… 2. Multi-Span or Continuous Beam Reinforcement
FAQ 2: what is including in Reinforcement Details of Beam?
1. Bottom Reinforcement of Beam 2. Top Reinforcement of Beam 3. Side Face Reinforcement of Beam 4. Stirrups || Transverse Reinforcement 5. Continuous Beam Reinforcement