@JoelTXCive,
I actually have been through some nice notes of the undamped free vibration case, but yours are presented so much better that I'm going to use those instead, so thanks! Perhaps I'll make a similarly formatted doc for the damped case and share it back here.
Hi all,
Thanks for the responses.
To clarify - no, I don't mean a value of damping. I understand this is impossible to predict and depends on many, many things for a structure (though we know typical ranges for different types of structures). I am referring to the derivation of the natural...
Hey,
I've always been curious as to how the damped natural frequency is derived:
ωd = ωn sqrt(1−ξ^2)
Does anyone have any literature? Is it empirical based on experiments?
Thanks
A couple of times on my internship I've had to design a simply supported slab over one span which I conservatively treated as one-way spanning. I calculated the amount of steel required in tension, and the senior engineer told me to specify the same steel top and bottom. When I thought about...
When designing a RC slab, it is typical to spec the same reinforcement top and bottom. When analyzing this section, do you assume the concrete contributes nothing (i.e. a neutral axis of 0) when analyzing the stress blocks as the compression steel would balance the tension steel? As such, the...
@WARose, Please could you elaborate? My thoughts were that the torsion would act around the centroid of the beam (where the bolts connect), and the top plane of the beam would try and twist left, while the bottom plane would twist right. I thought that the axial stiffness would prevent the top...
Hey.
I have attached an image of my query. I have timber beams that support decking that is tied into the beams using lag screws that provide lateral restraint. Attached to the left support beam is a post at approx 1m c/c along the length of the beam. The design code requires me to check...
Hi Dik. That was very well explained (and I was able to follow it!), thank you. I will take a look into shake down behaviour and see if I can further my understanding a little more.
@KootK, forgive my crude drawing (from MS Paint haha!) but I thought this might illustrate my thoughts better to see if I am on the right track. If the moment rotation capacity of a section is plotted in black, with (phi)Mp representing the ultimate capacity we design it for (assuming section 1...
@jayrpd12, My apologies, I don't think I explained myself clearly in my first post. I understand the principle you outlined in your post. However, I was asking whether it is of concern that it is possible that section undergo loading that would take it beyond the yield point but within the...
Hey everyone.
I have a question regarding ultimate limit state design. Using this method, we calculate member capacities based on their maximum plastic capacities. We then select member parameters based on the factored loads and materials, so that the materials do not reach failure during their...
@Celt83, Excellent! Thanks for the response. I figured that the minimum reinforcement equations would typically limit the steel from developing too much strain, but couldn't find any solid data.
Hey. So I'm looking at RC beam design, and I'm aware that beams are typically designed to be tension controlled, i.e. at the concrete rupture strain (0.0035), the steel should be beyond the yield strain. I've read that it is good to aim to have the steel strain at around 0.005-0.008 when the...
@canwesteng, As you said, the cracked concrete would reduced the stiffness of the connection, so would the beam begin to behave more like a pinned connection? (I understand in reality there is no such thing as a 'pinned' connection, as connections are always some form of semi-rigid).
