Expansion joint on Mat Foundation

[pplbb2011]

Hello There.

I have a mat foundaiton, 40m * 20m (LXB), with several extreme equipment load on top, settlement in each point is asked to be consist since those equipments are connectted by rigid large-size pipe. I am going to study it via finite element analysis. My question is as follows:

1. Whether I need set expansion joint for such large mat foundation,
2. How is such expansion joint modelled in FEA if needed?
3. Is there any impact to the foundation settlement if expansion joint is set?
4. Any other joint, e.g. control joint, shall be considered?

Thanks in advance.

 

[ishvaaag]

You need to identify in your code any extant mandatory expansion joint (even if related to the particular way of design). Quite likely the walls would at 40 m long require such expansion joints in the standing building foundations' code in Spain. I however am still reluctant to excessive jointing in walls and mats, for integrity and monolithism can make for any advantages purportedly gained from dubious jointing from a waterproofing viewpoint, that uses to be the case when referring to cellars.

We have worked on far bigger mats for buildings without any joints at level -1, perhaps 4 times that long. No probs have resulted. These were thick structural mats, say on the order of .6 to 1.1 m thick.

A proper expansion joint structural model needs to show the expansion joint in the mat. Other than that is ordinary structural modelling, that may need to use (depending on the attempted approximation of the behaviour) software able to portrait the geotechnical aspects of the soil.

The impact of the expansion joint in settlements should be small, but there maybe some, since the lack of continuity causes some different working loads in the soil. However, for foundations, except from big rigidity of the foundation and/or joined superstructure, the main influence comes from magnitude and position of the loads.

I normally for thick mats with enough thickness and rebar would try to avoid control joints affecting the structural mat.

 

[pplbb2011]

Thanks ishvaaag.

I didn't find any mandatory spec for mat foundation that expansion joint shall be set, thus i am not going to apply any joint in this mat footing.

 

[hokie66]

A 40m x 20m mat is not large. Cast it in one piece. Even if you have to have a construction joint, it should not be a movement joint.