Thanks Agent666. Everything you said makes sense. In the end, there is definitely not enough fee to cover all the extra time required to do it this way. If it was a smaller structure I might have worked on it for the challenge of it but I get myself in that trap too often and then stress out...
Anyone ever pushed a braced frame off the column centerline like this before? See images below. I've looked at AISC design guide for brace connections and in the manual but don't see any mention of this scenario. The largest brace force is 30k in a 9 story structure.
It seems that this would...
Thanks JoshPlum. I did each of the things you suggested. Running it without P Delta did help but was not the cause of the long run time. I found some overlapping beams and diaphragm connection issues that fixed it. Now it will run in only a few minutes and I was able to compare second and first...
When I run my model for a 4 story building with 5 moment frames the Pdelta and DAM takes an hour for the initial run.
Does this sound like a normal run time? Is it acceptable to analyze 1 bent only for the stability check? All frames are the same.
Can anyone point me to a good example for a low-mid rise steel moment frame design example? AISC steel design guide 5 is the most recent example I have found but it is dated 1991 with a second printing in 2003. I would like an example that follows a recent edition of AISC 360.
Specifically I...
I just discussed the project yesterday with the architect and he's agreeing to go with steel for this job. I told him it would be quicker designing it in steel and that seemed to change his mind. I'm relieved, however, still glad I've done all the preliminary concrete design just to get more...
Thanks for your response KootK, I've been meaning to get back to you but I've been trying to find some good examples of how to analyze the flat plate for lateral loads. I want to get a good understanding of the lateral capacity of the flat plate/column connections themselves before analyzing the...
Ditto what Dave Atkins said. Check the criteria in ASCE7 to see if you can use a 3 sided diaphragm. Or go back to the owner with a list of proposed changes to the design such as longer shear walls or introducing the steel beam and frames and let them decide which way to go. You could spend a lot...
I'm trying to determine the best type of lateral system for a 9 story apartment building only 17' wide x 60' long. Using a series of closely spaced steel moment frames (R=3) with a couple lines of braced frames seems to work well if I use cmu side walls and hefty concrete elements at the...
A couple things which you may have considered already:
1. What is existing soil capacity and what type and size are the footings?
2. A very small eccentricity in the loading of the thin wall will greatly reduce capacity. ACI 530 addresses this and unless you are supporting joists on both sides...
Not sure how useful this is but I once designed a steel stair, which, when built had a measured frequency of 11Hz. There was very little dead load so the vibrations were not damped and if you did a heel-drop at mid-span of the stair run you could definitely feel the vibrations.
If the angle or channel is stiff enough, I would say that the shear could be distributed evenly among all anchors. Hopefully you also have a fully grouted CMU wall. However, As dik mentions, you should account for tension as well as shear in the upper row of anchors.
Darthsoilsguy: This is a case where the facade engineer does not have a license in this state so it appears they hired an engineer to stamp the drawings who is licensed in this state (who I'm calling the EOR). The EOR and the design engineers office are not in the same state either. The EOR is...
Yes I think ACI allows it but I'm just cautious about using it for sustained lateral loads such as at basement walls. If the stress is really low then fine but I also see a lot of bad CMU work done by small contractors.
Thanks for all replies. I don't know if the design engineer is licensed in this state but it seems it's moot if they did not seal the drawings. I won't go into further detail About the epoxy but the panels are stone and on a ceiling directly over public and hung using clips epoxied to stone and...
If the wall had buttresses spaced horizontally a distance that was less than the vertical span between supports, it may be better to design the wall to span horizontally. Technically, if the ratio of vertical to horizontal span was not too high you might get some two-way action but I've never...
I'm inspecting some safety critical facade installations which the contractor has installed using a different type of epoxy than what is on the sealed shop drawings. As the Special Inspector I told them they needed to get the changes approved by the EOR but they only got an email statement from...
Thank's Ron. I really do make all the engineering decisions and do all the engineering and design work, calcs, etc. and believe this is the standard way this type of work is done. I'm basically the "in house" engineer for some of these fabricators and contractors. When the EOR requires them to...
