What is a force envelope?
Can we use a force envelope for structural design of column?
Entry level Civil & structural engineers can use this forum space to discuss this topic. Many times, engineers are confused about the load combinations and how to interpret the results using force envelopes. Use this forum space to discuss every thing about loads,combinations and envelopes.
Please see the blog and video on this topic HERE
Envelope has nothing to do with staad or etabs. It is nothing but a super imposition of the force diagrams of each combination. So if you draw a BMD of a beam for 1.5(DL+LL) combination and then draw for each of the other combinations over that and produce 1 single diagram , that is a bending moment envelope. This simplifies your understanding of the maximum values. Basically you get the entire forces of each combinations in a single place.
Now the questions are
1) can we use an envelope created and then design columns
2) can we design beams having torsion using envelope.
If not why? :-) Any one can attempt to answer or see our upcoming blog.
I think the concept of envelope is using for getting the critical force to determine the steel ..I used Staddpro for desiging (Having little bit of knowledge in Etabs).From stadd I use the load list comment for analysis.. So I get direct Ast for column design ..But beam I take the moment by using envelope..
Am not much more familiar with the concept..
Please explain it sir
What do you mean by outcome 🙂 Can you elaborate
It is the outcome of all the max. And min . Forces that exists in the load combinations
Envelope should be used with caution. It gives minima and maxima of forces and moments individually. Envelope can be created as a combination to assess the behavior. We Use it to understand the deflection, sway etc. We should Never use it as load combination for designs.