Expansion joints

[hussein]

expansion joints are used in large structure building , but i confuse about how much distance can be go without exp. jt and in there is footing the exp. jt pass it or not.

i have abuilding 57mx34m the provider designer make exp joint in long direction and i find there is column at each side of exp jt .

 

see attached dwg.

is there aspecific note in aci code advice for this case?

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[Waqar Saleem]

Dear Hussein,

One reason for expansion joint is to avoid shrinkage and temperature cracking, basically expansion joint is a weaker zone intentionally created to direct the cracks or release the stresses due to hydration of cement. 

if concrete dimension is 150ft-200ft, it is advisable to provide expansion joint or shrinkage strip to avoid shrinkage/temperature cracking.

To avoid cracks try to have proper mix design from a material engineer, sometime excessive cement content has been used in mix and assumed that this extra cement will give strength but thats not true, I have seen adverse temp cracks in 500ft long 15' high basement retaining wall, even wall was not loaded vertically or backfill, mix had extra cement content and there was no expansion joint in the wall along the length.

 

Regards

 

[hussein]

thanks a lot , but the main concept can we put exp. jt in footing by splitting it into two parts without weak the structure , if no how we will make exp joint in this case

[hussein]

thanks a lot , but the main concept can we put exp. jt in footing by splitting it into two parts without weak the structure , if no how we will make exp joint in this case

[Waqar Saleem]

no need to provide expansion joint in foundation 

[Ayesha]

  On 11/1/2017 at 11:27 AM, waqar saleem said:

no need to provide expansion joint in foundation 

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@waqar saleem, Did you mean for this foundation or for any foundation?

[Waqar Saleem]

  On 11/8/2017 at 3:36 AM, Ayesha said:

  On 11/1/2017 at 11:27 AM, waqar saleem said:

no need to provide expansion joint in foundation 

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@waqar saleem, Did you mean for this foundation or for any foundation?

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i mean in this case no expansion joint required, but if raft/foundation dimensions are large enough, expansion joint / control joint will be required.

Regards

[WR1]

Expansion joints in superstructure are provided for lateral movements e.g. from wind/earthquake/temperature/geometry. No need in foundations as soil has sink down effect for temperature and earthquake and winds and geometry effects are above ground.

 

[Fawad]

  On 11/1/2017 at 7:04 AM, waqar saleem said:

if concrete dimension is 150ft-200ft, it is advisable to provide expansion joint or shrinkage strip to avoid shrinkage/temperature cracking.

 

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What is shrinkage strip ??

 

[asadishaq]

Shrinkage strips are temporary joints that are left open for a certain time during construction to allow the shrinkage to take place without inducing stresses.

It is usually 2 to 3 feet wide across the entire  building and should be cast 2 to 4 weeks later than the adjacent portions. 

[Fawad]

  On 3/27/2019 at 6:29 AM, asadishaq said:

Shrinkage strips are temporary joints that are left open for a certain time during construction to allow the shrinkage to take place without inducing stresses.

It is usually 2 to 3 feet wide across the entire  building and should be cast 2 to 4 weeks later than the adjacent portions. 

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Thank you @asadishaq

Is there any code reference for shrinkage strip ??

Architect is not allowing for any expansion joint in a plan of area 80mx50m.

Normally grid to grid spacing is 12mx12m panel over the area of 80mx50m.

Thermal expansion of 80m long concrete comes approx 32mm with 40 degree Centigrade change in temperature. Coefficient of thermal expansion of concrete is 9.9e-6 per degree centigrade.

i.e (80x1000)(40)(9.9e-6)=32mm

I have provided top reinforcement more than required at the roof slab and provided an expansion gap of 100mm in my 80mx50m structure with nearest existing building.

Am i doing it right ???

[asadishaq]

Based on Technical Report No. 65, Expansion Joints in Buildings: issued by Building
Research Advisory Board, Division of Engineering, National Research Council, USA.
As per Figure 1 in the above referenced publication, the maximum allowable building
length without use of expansion joints, for design temperature change greater than
70º F (39º C) will be 0.85x350=297.5 ft = 90m.
In view of above, we would like to avoid expansion joints in any building which is
less than 90m in length, except where a seismic joint is required due to configuration
of the building (plan irregularities, re‐entrant corners, etc.) or due to different lateral
force‐resisting systems for the two parts of the building.