Why do we need an expansion joint in SLAB? And which type of slab in which we need?

[Quest Bot]

Why do we need an expansion joint in SLAB? And which type of slab in which we need?

 

[Dnyan Deshmukh]

Concrete do expand and contract.
According to IS 456, the expansion joint need to be given in structure whose length goes beyond 45 meters.
It is also up to structural consultant, either to give expansion joint or not for a structure which goes beyond 45 meter base on his own calculations.

If the structure does not have expansion contraction joint, it may lead to cracking of members if not designed properly.

 

[ALLAN YANANA]

Why do we need an expansion joint in SLAB? And which type of slab in which we need?

Expansion joints are maninly to avoid cracking of the members and it depends with the desiner

 

[amd007]

Why do we need an expansion joint in SLAB? And which type of slab in which we need?

In building construction, an expansion joint is a separation or gap given between two continuous structures which extend beyond say 40 to 50meters.

This arrangement is given to address or to relieve stress on building materials caused by building movement induced by:

• thermal expansion and contraction caused by temperature changes,
• sway caused by wind,
• seismic event like earthquakes etc.

Because the joint bisects the entire structure, it marks a gap through all building assemblies–walls, floors, roofs, etc.

Expansion joint systems are used to bridge the gap and restore building assembly functions while accommodating expected movements.

The term “movement joint” has been widely adopted in preference to “expansion joint” as it more appropriately encompasses the fact that building movement results in both compression and expansion of the material installed.

For example, when a structure heats up, the building materials from which it is built expands This causes the “expansion joint” to close down, thereby compressing the expansion joint system installed in the gap.

The usage of expansion joints is predominantly seen in large buildings which have acquired a larger area than it's height.