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  1. JoshPlumSE

    Return to RISA?

    This is a really good point. I'm not sure if the industry has standardized on a term. But, I tend to call these "super elements" where the meshing is handled internally, meaning that the user doesn't have to worry much about the mesh itself. I know the CSI programs (the company I work for) have...
  2. JoshPlumSE

    Learning Structural Connection Types – Pin vs Fixed (Real World Example)

    I'm with rb1957.... You KNOW that both connections were designed as fixed connections because they're both cantilevers. I'll quibble with some language here: 1) In reality all real world connections are somewhere between fixed and pinned. 2) AISC tends to use the terms "fully restrained"...
  3. JoshPlumSE

    Yield Moment in Hinges vs Section Designer, Why the discrepancy?

    I'm just guessing here.... But, I'm thinking this is a units conversion issue with the program.
  4. JoshPlumSE

    Negative Eigenvalue for 16-sty Building with 2 transfer floors

    Have you used the "check model" feature to check for duplicate joints or such? When I did this, it flagged joint 996 and 991 at L2 as being too close to each other. I changed the coordinates of 991 so that it lined up perfectly with 996.... I'm hoping that fixed the problem, but I haven't run...
  5. JoshPlumSE

    Raft on piles

    The danger is a differential settlement between the two types of foundations leading to cracking in the slab and such. Regardless, I would still design the pile portions of the foundation as if they were not connected if that leads to higher pile forces. Then design the slab as if they are...
  6. JoshPlumSE

    Raft on piles

    I have run into similar (but not exactly the same) circumstances before. Situations where the stiffness of the structure caused a load re-distribution at lower levels that would not agree with what the same location at a higher level would get. In my case, it was shear walls where the upper...
  7. JoshPlumSE

    Valid Pin Boundary Condition?

    Yes, this is generally considered a "pinned" connection. However, if there were a small amount of moment, then you could justify it with a hand calc. I had a case where I had a very small equipment support column with a base plate like this. No seismic load. Minimal wind and gravity loads. I...
  8. JoshPlumSE

    Clouds and models

    This is the entire problem, isn't it? The science is NOT very well understood. That's how HONEST science actually works. Lots of different theories are proposed and tested. Revised, discarded or improved. Unfortunately, the politicians, neo-marxists, and activists all want to share the...
  9. JoshPlumSE

    Return to RISA?

    Oh, they have definitely added staff. Some of them are probably very good. The issue is really that they've lost a lot of institutional knowledge.... You have to think of a legacy program as an old building that was built for one purpose and has been re-modeled and re-purposed over and over...
  10. JoshPlumSE

    Return to RISA?

    That's a really good point. Also, keep in mind that the reason why I frequently give caveats explaining my bias against RISA is because they have threatened me with a lawsuit in the past. Specifically for my posts on sites like this that were truthful, but which made the company look bad...
  11. JoshPlumSE

    ASCE 7-16 15.4-6 - Approx. Seismic Period Follow Up

    Whether or not your software accounts for the P-Delta softening effect in the eigen solution / natural period calculations can be tough to tell. When I was at RISA, the company exclusively used the "secondary shear" method of accounting for P-Delta. The problem is that this doesn't affect modal...
  12. JoshPlumSE

    ASCE 7-16 15.4-6 - Approx. Seismic Period Follow Up

    We're talking about using the Rayleigh method to calculate the natural frequency of the structure. Right? In this case, the only thing that matters is the lateral forces applied, the lateral deflection and the mass / weight at each level.... for the most part. But, take a look at that example...
  13. JoshPlumSE

    How can I stop water entering under porch and seeping through basement walls?

    There are easy ways to "plug" the hole as well. I had a similar issue with my parents' house 25 (or more) years ago. I went through the crawl space under the house looking for anywhere I could see "daylight". I had some self expanding foam stuff that I got from Home Depot and just sprayed it in...
  14. JoshPlumSE

    Legal Thoughts on Stamping Plans

    I don't think it's all that uncommon to stamp another engineers plans / calculations. a) This happens EVERY time you have a junior engineer doing work for you. It's just that the stamping engineering is taking "responsible charge" for calculations and plans. Presumably because they have been...
  15. JoshPlumSE

    Restoring Gold Standard Science

    I was not understanding the following part of it. So, I looked it up and found this: i.e. Global warming is going to cause x, y, and z withing the next 10 years..... Ten years go by and x, y and z do NOT happen. Ergo, the theory is basically false....
  16. JoshPlumSE

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    Hey.... That's the one I put together for the RISA training manual on dynamics. I always liked putting together a classic hand calculation to demonstrate the validity of a feature in the program.
  17. JoshPlumSE

    Retaining wall repair rec

    Honestly, it would help to know a little more. Total length of wall, height of wall. And, pictures. Another question is whether you believe the safety factors for sliding and overturning are sufficient.... It which case it's just an issue of reinforcement of the wall. Concrete or...
  18. JoshPlumSE

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    I should also point out that I did an example problem (when I worked for RISA) that demonstrated how VERY accurate this method was when compared to a standard Eigensolution.
  19. JoshPlumSE

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    Yup, simple Rayleigh method. When I've done this in the past, I've used whatever lateral force distribution I've already applied to the structure. Might be wind load, might be seismic. I don't think apply a single load at a single floor would be a good idea though....
  20. JoshPlumSE

    Wood post Cracks

    I agree with the comments that this is just natural checking of a large sawn lumber column. But, speaking as someone who's parents experienced this at their house.... I KNOW that a homeowner doesn't want to hear "it's fine". They look at it and think, "This just looks unsightly. Is this going...

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