HDStructural:
Thank you for your detailed reply. I was thinking along those lines, but if we take an extreme case where 25*tw is say half the depth of the beam and the web stiffeners are in line with the top & bottom beam flanges, the length of the web is too long. Would multiple web stiffeners...
Question:
When checking the member strength of web stiffeners acting in combination with a length of a member’s web, the computed active length of the web is given by 25*twc (25 x the thickness of the column’s web). Ref: Salmon & Johnson p.895 and LRFD-K1.8
Why isn’t the full beam depth D...
I am looking for suggestions on how to repair two "blemishes" / rust spots in a residential pool slab. One adjacent to the floor drain, the other is in the middle of the pool bottom slab. It looks like they are the result of pin-holes in the concrete letting water get to the rebar. I'm...
I have a floor slab to design to support storage rack W6 posts with a 14 kip load. The PCA Charts do not have a wide enough range for the X and Y distances between posts to cover my situation (X = short distance = 138" and Y = long distance = 240"). I'm wondering what others do when they run...
I am looking for a reasonably priced, intuitive software package to manage multiple projects (5-10) as an Owner's representative. The main functions would be to organize and manage contracts, change orders, drawings, drawing changes, submittals, meeting notes, etc. While scheduling might be a...
I'm working on a remodeling project for an 1955 heavy industrial building. I have the original drawings! There is a note on one of the wall sections that calls out "H.H. Robertson 2Hr. Firewall" as the wall panels. The section does not call out a wall thickness, but it looks to be 3" or 4". Does...
The alloy is 6063-T5, and the member it is used in is a extruded, not welded. I think Mike has sent me on the right track, thanks for all the input! Once I get it worked out, I'll do a follow up post here.
IFRs:
Thank you, you have clarified a number of my problems, not the least of which was thinking in terms of single value properties like steel, when an aluminum alloy has multiple values depending on thickness, tension, compression, shear, or bearing. So, the Fy = 30,000 ksi has no place in my...
Thanks Mike,
The alloy is noted on the first page, 6063-T5 and the equations are in the first column, but you are correct, you wouldn't can't see them or manipulate them. The S1, S2, and >S2 are strictly a function of the "base" allowable stress - a constant * b/t.
The negative numbers pop out...
I’m designing some aluminum extrusions for use as the structural framework for large horizontal sliding doors. As most of you know, trying to find the correct allowable stresses to use for aluminum extrusions is no simple task because the allowable stresses are dependent upon the Alloy, the...
Yes, the wires of the mesh run in both directions, you can see some of them on the far right of the photo. The mesh wire is in a rectangular pattern, not square. This must be some type of engineered system, because the joist are so light, there is also a diagonal bracing system, which you can...
I have run across a structural floor system I have not seen before and I'm looking for design information. I have the architectural drawings dated 1953, but no structural drawings. The system is composed of 10" deep "light" steel joist labeled #102SJ with what looks like a light gage steel...
A concrete sub-contractor poured a structural deck over an accelerator room scheduled to house radiation equipment for cancer treatment. The deck is approximately 3’ thick with an integral concrete beam that is 6’ deep. Based on 3 day and 7 day cylinder breaks, both of which were higher than the...
Thanks for your comments. This project has a minimum unit weight requirement to achieve the necessary shielding for a medical device. The shielding is a function of the concrete thickness and unit weight. The wall thickness is fixed at 4'-6" which drives the need for the minimum unit weight...
In general, for the same local aggregates & sand, is the unit weight of the concrete increased by going from 1" stone to a pea gravel size stone in the mix?
We have a project that requires 4,500 psi @ 148 pcf concrete and the "standard mix" designs are producing 145 pcf concrete at the site...
Good comments all and I agree in principle. I always had the feeling that the EOR was just playing with numbers, that is using the higher cylinder break strength as one justification to say the beams where OK. As I recall, this project never went to court, but a settlement was reached, with...
I've thought about this question a few times over the years and I'm wondering what you fellows think about it.
Many years ago, during the construction of a local precast concrete warehouse, a dispute arose, while I was not involved in it (really I wasn't - honest!) here is the gist of it: The...
I'm trying find a way to satisfy the deflection requirement for this section of the code for an EXISTING installation. The code section requires that the differential deflection between two adjacent glass panels not exceed the thickness of the glass panel under a horizontal loading of 50 plf...
