![]() ![]() Differential temperature effects can also greatly reduce the cracking moment. Shrinkage greatly reduces the cracking moment, which greatly increases deflections, even with symmetrical reinforcement. Significant loss of tension stiffening happens in weeks or days, rather than years. The loss of stiffness immediately after cracking is much greater than given by the ACI formula. I don't know the Canadian code, but if the deflection provisions are similar to ACI 318 the problem with doing a more detailed analysis to sharpen your pencil is that the calculated deflections are already way over-sharpened, especially for lightly reinforced sections: RE: Concrete Beam Effective Inertia Shotzie (Structural) If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it. I like to debate structural engineering theory - a lot. And it's the chunk of the span contributing most to deflections. I'd think it even more prudent for a uniformly loaded simple span as the moments tend to stay pretty flat over a good chunk of the span. The advice given above regarding midspan/end moment of inertias was mostly developed for continuous beams rather than simple spans. I'd be happy to run some things for you if you're inclined to attempt some bench marking in the future. I bet one could get this done in a page or two of programming.įor my precast work, I use a program called ConciseBeam that basically does what you've described. ![]() My vision was a MathCAD worksheet that would basically do old school double integration method, using a variable I. In the context of spreadsheet making, doing it once isn't so much different from doing it a thousand times. ![]() Would it be possible/correct to discretion the beam into shorter sections and compute the deflection cumulatively (going back to my structural analysis notes from University) ![]()
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