Deflection in beam design implies relatively slow (nearly static) deflection of a beam. A beam subjected to vibrations means that you need to be looking into a dynamic or vibration analysis. That will tell you the vibration frequency, amplitude, etc and compare that to the allowable limits of the equipment.
Dougantholz - It seems that deflection limits are up to the engineer who is designing, and not to exceed the limits set forth in code (l/240, l/360, l/600, etc.). Lets just say an l/360 delf. limit for a particular beam comes out to be 1.45". I personally try to keep deflection for any beam under 1".
I have been pondering allowable deflection limits for our residential design standards for high-end residential *FLOORS BEAMS*(wood framed with LVL, glu-lam, and steel beams). I am trying to develop a list of criteria for younger engineers, and I would appreciate some input from some of y'all...
The proper Global deflection limit to use also has to do with what is on the roof as a roofing material - this looks like a rafter/beam situation is why I mention it. If the roof is tile, deflection is very readable from the ground, less so with composition, but still readable.
Hey guys, Why are deflection limitations specified as a fraction of the span length, such as L/360 or L/240? I'm having a hard time picturing this criteria, it apears to be more of a deflection slope or gradient, rather than a maximum deflection limit, such as 1" or so. Can someone show a simple...
Deflection criteria are put in place for a variety of reasons, including aesthetics, limiting cracks, mitigation of creep, and to force sections to be more resistant to "dynamic" deflection such as floor "sponginess".
The code deflection limit charts for Floor Members simply states: Live load = l/360 Nothing for Wind D+L = l/240. So am I only checking the Live Load deflection and the Load combination (D+L) deflection? Does my Load combination of D+0.75L+0.75(0.6W)+0.75Lr not need to meet l/240? Or is...
It depends what the goal of the deflection limit is. For most deflection limits in structures, the end goal is either user comfort or preventing issues with non-structural elements and finishes. In this case, relative deflection (L/X) is usually the target. This limit reflects the local curvature or deformations at play.
A fairly simple method of finding deflection at any point is to draw the bending moment diagram for the actual beam, then use the Conjugate Beam Method to find rotation and deflection at any point on the span. The Conjugate Beam method for a simple beam is a useful way of applying area-moment principles.
I have a question regarding Structural Deflection Limits. The way I see it, there are three ways of going about it - Follow the IBC verbatim, or use ASD load combinations, or load that aren't factored at all. For example: What are the appropriate combinations to used if I have both a floor...
