Is it mandatory to provide expansion gaps in buildings?
Even it is mandatory, are there any special cases where expansion joints are not provided.
Will it depends on climatic condition of region?
Who is responsible to provide expansion gap? Architect or Structural engineer?
Designing a flat slab for temperature loading will require excess rebar quantities specially if the spans are more than 6m.
There are three options to provide expansion joint (E.J).
Option 1 : Providing double columns and separating the building.
Option 2: Providing ledge beam at one end of the EJ and releasing the slab coming
from the other end. Elastomeric Bearing pad shall be provided on the ledge beam nib to allow for the movement calculated as per the wind & seismic drift. Note: EJ thickness is not a magic number it depends on the drift it should be calculated as per ASCE7-10( if using US codes) building separation equation.
Option 3: Provide Shear connectors. Refer Ancon shear connector website for further details.
Before selecting any of the options above it should be discussed with the architect for Architectural feasibility of the location and type of EJ.
In terms of economy option 3 will be the most economical solutions and it will safe time of construction. Option 1 & 2 shall be coordinated with MEP to detect the duct clashes if any.
All joints that we see in buildings,necessarily need not be an expansion joint.
Joints are introduced in buildings due to various reasons and expansion is only one among the many reasons.
Some of the reasons other than expansion is as listed below
a) Geometric irregularity
b) Mass irregularity
c) Addition to existing structure
Is it mandatory to provide expansion joint?
The answer depends on if it is needed.Generally as per IS 456, Structures exceeding 45m shall preferably have more than one joint.
However in modern buildings,clients prefer not to have expansion joints. In such cases a temperature load analysis is needed to be performed.This can be easily performed in software like ETABS or STAAD Pro. Joints release the additional stresses in the gap where as temperature analysis accomodates the stresses and we need to design for it by checking if the provided steel is adequate to take care of temperature stresses.
Can we avoid other joints (those other than expansion joint mentioned above )that are provided for structural reasons?
Preferably no as the best way to design is to avoid irregularity
Will the climatic condition decide the need of the expansion gap?
As per code it is the length of the building that decides.Code also allows to do a detailed analysis.When we do a temperature analysis , the climatic conditions will become a factor as the varition in temperature is what decides the stresses.
Who is responsible to provide expansion gap? Architect or Structural engineer?
Surely it is a structural decision in co-ordination with Architectural requirement.
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