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.
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".
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...
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.
Here in New England, the major supplier of pedestrian bridges limits vertical deflection of the main trusses due to pedestrian live load to 1/400 of the span, unless specified otherwise.
Hi folks, When Checking for serviceability of beams do you take the absolute deflection (meaning the deflection of the beam + the deflection of the supporting beam/girder at the connection point, if the beam being check is the intermediate beam) or the local deflection (meaning the deflection of...
Hi, Consider the case of a cantilever frame as seen in the attached picture. When you consider the roof beam as an individual beam with one end fixed, I consider the vertical deflection limit as span/250. What would be the vertical deflection limit of the roof beam when the whole frame...
