Expansion joints must be provided in concrete structures to accommodate expansion due to thermal effects. Concrete expands as it absorbs heat and shrinks as heat is lost.
Different specifications apply to expansion joint width sizing depending on the type of building.
The method described here for sizing an expansion joint is based on the guideline “ Expansion joints in civil construction, Technical Report nº 65 ” of the Standing Committee on Construction Technology of the Federal Construction Council.
They created a table that will help determine the length of the structure that can exist without an expansion joint depending on the type of structural shape.
However, they also provided equations to calculate the length of the building depending on temperature changes.
Use the figure below to determine the maximum allowable building length without using expansion joints for various planned temperature changes.
It should be noted that the values obtained in the table must be changed according to the conditions mentioned below in the table. Furthermore, this is not limited to expansion joints in concrete.
According to the Directive, the above table is directly applicable to buildings of beam and column construction with base hinges and heated interiors.
If the conditions are different from this, the values obtained in the table must be changed as follows.
- If the building is only heated and has articulated support bases, use the length allowed according to the table.
- If the building is air-conditioned and heated, increase the allowable length by 15% (assuming the environmental control system is running continuously).
- If the building is not heated, reduce the permissible length by 33%.
- If the building has fixed column bases, reduce the allowable length by 15%.
- If you want the building to have significantly greater rigidity against lateral displacement at one end of the plan dimension, reduce the allowable length by 25%.
If one or more conditions are true, form the algebraic sum.
Furthermore, we can calculate the width of the expansion joint taking into account the factors specified in the guideline.
