ztengguy,
I agree. You should get paid for a change. The scope was up front: design a bridge. The building budget is 25% less so I'm looking for ways to save cost. The engineer said he'd do one more design but that's it. The thought was a truss might be more economical. The response was...
Thanks Jed,
I've been called Jethro.
So a full depth truss probably isn't economical as a solution from what I gather from your post. I like the idea of haveing the top be a guardrail of sorts. Sometimes with structural engineers I feel like a patient who isn't going to question the doctor's...
At what distance is it more cost effective to use a truss design for a walkway bridge versus a beam design with moment frames for the tube all cross braced?
I am told 80'.
Parameters: 60' span; 6'x8' walkway; enclosed on 2 sides with storefront; LL:100psf TL:127; exposed roof deck with...
oldrunner
Yes, things can always be better.
However, an AHJ isn't going to care one way or the other whether one's design is too much or too costly; too little, probably. The problem being discussed isn't whether it's going to blow down; it's been proven it won't by another engineer ...
Oldrunner,
Just for the record, I did take structures in college; otherwise I wouldn't have a clue about what an engineer was talking about. I am not an engineer, obviously. I'm trying to understand why this specific engineer considers his design (more expensive, more than required) to be...
RFreund and AELLC,
The SE of record maintains that this 4' panel method is stronger than a 30' or 100' long traditional wood shear wall. Again, his primary statement is that this method won't 'crumple like a piece of paper'. It is more expensive because of more anchors and because the SE...
oldrunner and jdgengineer,
Thank you both for reading through all of the posts. I apologize for the length. My main intent was to see how a 4' panel system is stronger than a 'continuous' shear wall; why the first won't 'crumple like a piece of paper' and the second, supposedly, will.
Each...
Cadair,
My hat's off to you.
I took your advice and called AWC. I talked with Loren Ross who was very enlightening. Wood shear walls are definitely not monolithic. The forces are in the 'chords' and the panels just keep the rectangles from becoming parallelograms.
I'm done pursuing...
Cadair,
Looking at the building as a bunch of I-beams is somewhat misleading because the wind force is transferred through the stud of the side walls up and down to the horizontal floor plates, the plywood deck, and then to the top and bottom of the shear wall. The load is not transferred...
Cadair,
Your points are well taken. I like that you have supported your position again and referenced another source. I will look at AWC ... again.
Given your position, how is a shear wall with hold-downs at 4' stronger than one with hold-downs at 28'. I'd say 100' but JAE would grimace.
I...
AELLC per "OK I see." (and to JAE)
The shear walls are as you have stated, some short, some long.
It is my understanding that jogged walls cannot be counted as one shear wall as you stated. Where the wall jogs, that jog takes load from the 90 degree direction whereas the other walls take...
AELLC per 'well in that case':
I don't follow how you get to a range. Some are 24' long, some are 48' long, some are 8' long depending on the wall layout by the architect. There was no real thought about structure from the architect's position so the shear walls got shoe-horned.
Actually...
Cadair,
Thanks for your post.
I agree with a lot of what you're saying but ...
To your fist point" If they don't act as a unit then how can the overturning moment be resisted by two hold downs, one at each end of a 'long' wall. You wouldn't be able to use the lever arm of the entire length...
AELLC per 'did some research' ...
I'm aware of the ATS system that compensates for wood shrinkage; the SE is not specifying this, just a standard all thread. He objected to the contractor even using straps instead because he said the straps would pop when the wood shrinks. So, he's aware of...
Yes,
In this case the project was on a tight timeline, foundations are in, and framing has begun. The design-builder is getting letter from another engineer which they're going to wave in front of the inspector. That won't do much good because the inspector won't say anything if it's not in...
