Building expansion joints 1

[ukengineer58]

Hi I am looking for some general advice on expansion joints in steel frame buildings using precast or composite flooring. What are typical distances etc people use

 

[SteelPE]

Try here

http://www.modernsteel.com/Uploads/Issues/April_2005/30740_fisher.pdf

And here

http://www.nap.edu/openbook.php?record_id=9801&page=1

If the second link doesn't quite work, you are looking to technical report #65 on expansion joints.

 

[ishvaaag]

40 m in Spain for both concrete and steel structures from 1960's to 2005; comment added that reduced to 30 m if the columns' stiffness was big, and augmented to 50 m if weak. These distances were given as those to which temperature effects could normally be dismissed, yet it prescribed ranges of temperatures for which needed to be checked, that were all except those buildings where insulation etc ensured the structure lived within +- 10ºC range. Generously interpreted that could mean well insulated buildings but everyone sees that not if considering the temperature at which built.

Current national code CTE as it stands would be more or less the same (40 m exemption of need to include temperature effects in the analysis for the ordinary buildings) except that has a more complicated prescription for temperature loads (must be akin to eurocode, many new things in it are); so as of now, in the end, the strict view is that you are to include the temperature effects and see that the serviceability limits are respected, whatever the length between joints; if only because they may be adding to other deformations and then not meeting targets of sound behaviour. This becomes truly required if 40 m are not respected.

Note that in general the distance between structural (building) joints are just a device related to the obliged consideration or not of temperature effects in the analysis. So you can project a building of any size as long as you prove its wanted sound behaviour is respected. Think for example of long span bridges; temperature has then its own relevance.

I have seen thermal cracks on façades 15 m long and inner (thermal) cracks on 12 m long. I have also seen cracks in irregular buildings 51 m long. Yet other where the outer skin is jointed (prefab could be, perhaps more typically curtain-wall and inner masonry is mostly floating on the structure have no problems at far bigger dimensions, say, 80 m long.

CTE when speaking of supported -not load bearing- masonry also specifies shorter lengths of continuous masonry work as per the attached table. Vertically I think there are other restrictions.

 

[a2mfk]

The Modern Steel article posted by SteelPE is a really good primer with formulas as well...

 

[ukengineer58]

Thanks guys. Links very useful, I am uk based but still applicable.

 

[a2mfk]

Yeah, I saw where you were from, but the forumulas are pretty simple with a little Imperial-SI translation the structure wouldn't know the difference!