Two-way slab design for point loads
Two-way slab design for point loads
(OP)
I wanted to see if anyone has any good literature on two-way slab design for point loads. I know that there is AASHTO for deck design using one axle or point loads, but these point loads a are smaller. Every example I've ever seen on two-way slab design is for uniformly distributed loads. Any help would be greatly appreciated.






RE: Two-way slab design for point loads
A Finite Element Approach to Reinforced Concrete Slab Design in GT STRUDL
RE: Two-way slab design for point loads
Check punching shear for the local point loads. Concrete is so good at redistributing, I would model as uniform.
If it is point loads at midspan, then find the equivalent uniform load to match the same moments.
Anyway, I didn't read the literature but I would think you could apply some logic and come up with a reasonable approach.
RE: Two-way slab design for point loads
RE: Two-way slab design for point loads
For relatively small point loads, especially if they are applied in the middle strip area, then equivalent frame or other simplified methods with distribution of effects into column and middle strips are ok. If the point loads are in the column strip area, they should not be distributed normally as their effect should be contained within the column strip and not distributed to the middle strip.
If they are relatively large point loads as in a transfer slab, then FE analysis to determine the distribution and reinforce accordingly for the concentrations in different areas of the slab.
RE: Two-way slab design for point loads
Just figure in the appropriate slab width in each direction based on the width of the point load, add in the other uniform loads over the same width strips, get the moments and reactions and design the reinforcing steel. No worries.
Mike McCann
MMC Engineering
RE: Two-way slab design for point loads
I humbly disagree that the Equivalent Frame Analysis method is always easier than FEA. With modern software it can be easier to make a reliable FEA plate model than it is to do discrete frame analyses with the Equivalent Frame Analysis method and marry your results together, especially if your office uses solid modeling as opposed to 2D drafting as we do. Approximate methods were formulated to 'approximate' what a reliable FEA model would provide for you internally... At the end of the day it depends on the exact problem parameters and what tools you have at your disposal.
RE: Two-way slab design for point loads