KootK, Thanks for the graph. Good to know that's how other codes handle the difference between Omega an R. Is the graph truncated? What is the Base Shear value corresponding to Du?
In ASCE the Cd value is somewhere between Omega & R. Where Cd is closer to R value for more rigid systems such...
Thanks for your input KootK.
C12.4.3 description is the basis of my understanding of the Omega load. However, I know before Omega load was introduced, people used to use R=1 to check for elements that needs to remain elastic. My guess is that the code committee determined that R=1 is too...
Thanks for all the replies. I agree that the only way to know that the RBS remains elastic is to check it for R=1. However, somewhere between Omega load and R=1 loading, there is no guarantee that the plastic hinge will form either. The energy dissipation mechanism within the SMF design may...
Thanks for all of your input. I think I need to clarify my question a little. I know bracing at the plastic hinge is required by code, and I know I need to provide that for SMF. I'm questioning is if a plastic hinge will really form in certain cases. Just because we call it a plastic hinge...
Hi jdgenginee, mike20793 & gumpmaster,
We've been getting a lot of push back from GC's about using Simpson SMF. The reasons being:
1. Simpson only allow 1/8" tolerance. This is a very tight tolerance for an existing building that is neither plumb nor level. Most GC's don't want to be...
I'm curious about how to brace the hinge points in a Reduced Beam Flange Special Moment Frame with a wood diaphragm. I've seen a lot of steel angle braces back to the wood diaphragm, but it doesn't seem like the wood diaphragm will be able to resist the code required brace load (6% of beam...
Josh,
I have the same question myself. It seems to me that one should be allowed to use phi = 1.0 when applying the overstrength load combination, i.e. comparing "probable" maximum seismic load (omega) to the "probable" strength (phi=1.0). However, I can't find anything in code to back this...
JStephen - Thanks for your explanation. It seems to me that the ability for the anchor to deform should include the length of the anchor that is allowed to stretch, not just a function of the material property. For example, if the bottom of a holdown is installed right at the concrete surface...
I'm curious if anyone has read the new ACI318-08 Appendix D, Section D3.3.6? Am I understanding correctly that if the anchor material is brittle, then the anchor design strength is limited to 0.4 x concrete failure strength per D3.3.3?
Why is the brittle anchor design strength a function of...
Thanks for all of your input, and here are some more info on the project:
The project is a 50 unit low-income housing complex consisting of four separate two-story wood frame apartment buildings. The areas of visible wood rot is at the cantilever balconies, exterior wood stairs & rails, and...
Hi Mike,
Thanks for the response. I was trying to see if there are specifications for treatment when the damage is only minor. And if there are standard specifications to allow contractors to determine "replace" vs. "treatment" options. I agree that "remove & replace" is probably the safest...
Hi All,
I'm involved with a multi-unit housing retrofit project which includes dry rot repair for many of the architectural elements. I'm wondering if there are general specifications for dry rot repair that I can use as a starting point. I looked into Masterspec index and didn't see anything...
TXStructural -
The Lenton ICC report is not current (2008), and the same goes for the Bar-Lock ICC report. The Bar-Lock couplers has a much larger diameter than Lenton couplers and it may be too congested to do the welding for my detail. The couplers will be in tension and need to develop the...
Mike,
I'm attaching the rebar to the face of a column flange, not rebar to rebar connection. The Lenton weldable couplers is like a large threaded nut, that can be welded to steel plates. The matching rebar will also have threaded end that can be connected to the weldable coupler.
Does anyone have recommendations for weldable rebar coupler? I have used Lenton weldable mechanical coupler in the past. However, I just found out that they don't have a current ICC-ER report for IBC. Are there other options for weldable couplers?
I'm using the coupler to attach rebars to...
