huangyhg

effective width for transfer slabs
does anyone have an opinion or know of a reference for the effective width of slab to use for a post-tensioned concrete transfer slab.
ron,
the british and european codes state:
"concentrated loads
the bending moment arising from a concentrated load may be distributed over a width of slab equal to the width of the load plus the lesser of the actual width or 1.2(1 - (x/l))x on each side of the load, where x is the distance to the nearer support from the section under consideration, and l is the span."
this is recommended for rc slab but there should be no difference for a pt slab. with a long span the above effective width can get quite large, i would place an upper limit of the column strip width on the effective width.
i recently saw this question asked on aci website and they came up with the following answer
q. does aci 318-02 give direction for dealing with concentrated loads on two-way slabs?
a. yes, the requirements for punching shear (two-way action shear) are equally valid for concentrated loads. section 11.12.5 gives restrictions on the locations of openings close to concentrated loads. for flexural design, the direct design method (section 13.6) is limited to slab systems where only uniformly distributed loads are used. slab systems with concentrated loads should then be analyzed and designed using the equivalent frame method of section 13.7.
see the following:
1) thread 507-20572 "flat plate with point loads".
2) pti publication "design fundamentals of post-tensioned concrete floors", pages 3-6, 3-7, and 5-5.
i think the guy is asking about the effective width to take in the design..if i'm right so take it as u like..for example 1m and then calculate the required tendons and strands for 1m
yes the effective width of slab to use to carry column loads on a transfer slab was my question. in the past i have used judgement but i was hoping to see what other engineers were doing.

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