huangyhg

how to calculate the maximum spacing between expansions join
i have concrete building has dimension (80 meter x 60 meter ) 5 floor i want to make expansion joint but the arch engineer refuse
i want to know if i can complete my design with out expansion joint or not, so i need any information or how to calculate the spacing between the expansion joint and if u know any web site can help me
this building has different temperature (22 inside and 55 out side)
swelm,
did you mean control joints?
expansion joint - you need it to separate the slab from other components such as wall, column, etc..
control joint - aci 318 recommended 3* slab thickness. for example, you have 4" thick slab, your control joints will be cut at every 12.
you may need an expansion joint. since you stated your problem in meters and degrees celsius i know you aren't in the u.s., but this may help....
i just have to chime in here, being an engineer trained in both metric and imperial, and having used both nearly every working day until my move to new zealand.
the imperial rule of thumb is as zestructural has stated, 3 times the slab thickness in inches gives you your maximum control joint spacing in feet.
the metric version is even more simple: divide your floor thickness by 0.028. done. units are consistent. i like to think about this as being akin to the minimum reinforcing in a slab... mind you, it is an order of magnitude off, but you get the idea for the mnemic.
quick summary:
3*slab" = jointspacing'
or
slab(mm)/0.028 = jointspacing(mm)
note that the metric version is conservative by around 2%. not all that great a concern, after all it is a rule of thumb (if a highly tested and often specified one).
good luck,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
i think the poster is referring to building expansion joints - 80m building = 262 ft. wide.
for that width of building you probably don't need to
have an expansion joint to divide your building into
two separate structures. (based on aisc figure 1-1 in the
manual for concrete structures)
swelm
you have to look at the effects on the floor and the supports of the amount of shortening/movement you are going to get. most of this movement will be due to shrinkage and temperature change. for a pt building there will be some for the axial prestress as well. you need to calculate the moments and shears in the columns and the moments and axial forces induced in the floors due to the restraint of these movements. creep of the columns and the floor will reduce the effects but they are still very significant.
80m is larger than my preferred maximum limit of about 65m but the actual limit depends a lot on the structural layout, temperature change, concrete properties etc and a lower maximum may be necessary.
if the temperature during construction is 55c (i presume you are in the middle east to experience this temperature) and the temperature during operation is going to be 22c then you have a very large temperature change to deal with in addition to probably fairly high shrinkage as the building is obviously air conditioned.
thank you for everyone add to me new information,and try to help me

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