Design of Plywood over Square Hole?
Design of Plywood over Square Hole?
(OP)
I am trying to design/analyze a sheet of plywood over a 24" x 24" hole. I would rather not analyze it as just a simply supported sheet beam over a 24" span because I want to be as accurate as possible. If anyone knows how best to approach this, it would be appreciated.






RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
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RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
another day in paradise, or is paradise one day closer ?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
We can make a life’s work out of damn near any problem, however dumb. The trick is, and the real valuable knowledge and experience is gained, by learning which problems are important enough to spend your time on. When your loads are generally conservative guesses/assumptions, and your allowable stresses, etc. have a factor of safety of 2 +/-, why would you try to fool yourself with an elaborate, time consuming, analysis method, on a problem where you can’t really even define the support conditions? With the advent of computer analysis, the almost total loss of any common sense or engineering judgement and our overly complex and convoluted codes and stds., we are mostly fooling ourselves into thinking that we have a more perfect and absolute answer. The funny thing is, the structure is smarter than we are; it can/does recognize a poor design (and analysis) and performs or fails accordingly.
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
Also, the OP did not tell us what thickness plywood is required for the application. So using 3/4" is a "slam-dunk"... what about 1/2" or 3/8"?
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RE: Design of Plywood over Square Hole?
RE: Design of Plywood over Square Hole?
(1) Cover the hole, but make sure the cover does not skid out from somebody's foot or when a pallet jack or forklift truck "pushes" the plywood from over the hole
(2) Cover the hole, but without anything sticking up to trip a person walking over the small hole. This isn't a irregular flooring where you walk around stepping carefully on each edge of each plywood over the whole floor. Nor should you require a person to look at the floor to be sure he/she isn't going to trip.
(3) Cover the hole, but with an adequate fire proof/removeable/permanent/temporary cover appropriate for the chemicals and purpoise (indoor/outdoor/rain water ice) problems that will (or will not) occur.
So, I have seen several cases where a small plywood piece over a hole is correct, and have tripped myself over small plywood boards that stick up, and have had to recover/rebuild small plywood covers (as FME covers) where a two-ply nailed construction was needed not for the weight of the plywood nor its strength across the hole, but so the cover would not get "kicked off" of the hole.
Form. Fit. Function.