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  1. MarkAJohn

    Response Spectra Analysis Question

    JLNJ, I can see that, if one beam on the third floor was going nuts, it wouldn't matter much to the total base shear. You can see that with a program like RISA-3D. However there has to be a better way to say it than "percent of active mass that is participating". After all, if you model a...
  2. MarkAJohn

    Response Spectra Analysis Question

    Thanks for the responses and references. I should have said my main interest is seismic response in buildings. I think the 90% is required by the building code but I can't seem to put my finger on it at the moment. I have heard the 90% number forever and have seen it reported in the results...
  3. MarkAJohn

    Response Spectra Analysis Question

    Can someone tell me what the following state means: “When you perform the response spectra analysis (RSA), at least 90% of the model's mass must participate in the solution.” It seems to me that the whole structure is in motion in all modes, so that 100% of the mass is involved in any mode...
  4. MarkAJohn

    Nested Command Error with Autolisp

    I found the answer on an Autodesk forum. The ALIGN command is an external command and can't be called with the command function. You have to call it as follows: (align (lastent) p1 p2 p3 p4) First you have to load it as follows (command "align") (command) That seems to make it work all the...
  5. MarkAJohn

    Nested Command Error with Autolisp

    Here is the code: ;No att editing here. ;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;bki.lsp - MAJ - 8-7-10 ;Type "bki" (without the quotes) on the command line ; ------ MAIN FUNCTION --------------- ;Main Function (defun c:bki ( / resp resp2 ss counter edata data1 data2 frac1 frac2...
  6. MarkAJohn

    Nested Command Error with Autolisp

    Hello, I’ve written an Autolisp routine which uses the “command” function. It works perfectly three times, with no errors and gets back to the command prompt. The fourth time I use the command I get an error: “Fatal Error, Commands may not be nested more than four deep”. I have looked to...
  7. MarkAJohn

    The 10/50 Seismic Acceleration

    I have heard of reduced seismic for retrofit of some existing buildings. Check International Existing Building Code (hope I got that right). But I don't think it was as much as 50% off. So, why would the Geotech suggest doing that? I wonder if the Geotech would be willing to stamp the...
  8. MarkAJohn

    Strength of Fillet Welds

    Connectegr, Thanks again. I'm gonna do all my fillets as leg times 0.707. Best Regards from seismic country, MJ PE
  9. MarkAJohn

    Strength of Fillet Welds

    I'll throw another question or two in as well: (1) Connectegr, you mentioned that it isn't allowed to test SMAW for the purpose of increased nominal strength. Where is that, AWS1.1? (2) I see fabricators weld 14 gage stair pans to stringers (e.g. MC10 or plate) without a little supporting...
  10. MarkAJohn

    Strength of Fillet Welds

    Connectegr, Many Thanks for your time and knowledge! Some of that I knew. I didn't know it wasn't allowed to test SMAW to justify higher strength. Best Regards, Mark Johnson PE
  11. MarkAJohn

    Strength of Fillet Welds

    More thoughts: You are, of course, right about who picks the process, the fabricator. If your in seismic country where the engineer picks the size, a fabricator might be more apt to use SMAW. If the fabricator is given the required strength and gets to pick the size, (not seismic country) I...
  12. MarkAJohn

    Strength of Fillet Welds

    Thanks to you guys for the responses. I believe Connectegr is saying you don't get the extra penetration with SMAW. That would be consistant with the old spec. which only allowed extra strength for SAW. Am I reading you right? Are you also saying that practically all fillet welds are done by...
  13. MarkAJohn

    Strength of Fillet Welds

    List: Here's one for the welding experts: In the old AISC 1993 Spec. (J2.2a) you used to be able to get extra effective throat on a fillet weld if it was done with the SAW process. In the 2005 Spec. this has disappeared and been replaced with a testing requirement. This could apply to all...
  14. MarkAJohn

    CJP in a Moment Frame

    Thanks Very Much Guys, I think I have what I need to state my case (that just a CJP to A36 plate won't work). This is a valuable forum! Mark Johnson PE
  15. MarkAJohn

    CJP in a Moment Frame

    This is an end-plate connection like the one shown in Fig. 12-6 (a) on page 12-8 of the AISC Steel Manual 13th ed. MJ
  16. MarkAJohn

    CJP in a Moment Frame

    List, I have an application where I wanted to weld a 50ksi wide flange (W8x40) to the face of a 1.25” thick 36 ksi plate and fully develop the 50 ksi wide flange. (it’s part of an ordinary moment frame and will be used in earthquake country) My client wants to do it with a CJP. I want to be...
  17. MarkAJohn

    LRFD desighn of Welds

    I was watching a webinar on the AISC site last night. the lecturer, who was from the Lincoln Welding Company said that check is usually not done. He also said you shouldn't use over-matched electrodes because otherwise shear on the fusion zone will govern. That's the reason for the notes on...
  18. MarkAJohn

    LRFD desighn of Welds

    Gentlemen, Thanks for the responses. Page 9-5 of the 13th considers moment through the thicknes of the webs. Not what I'm talking about. Page 9-6 continues to page 9-6 where you find 3.09D and 6.19D. In the first full paragraph on page 9-6, it say the method is for calculating the minimum...
  19. MarkAJohn

    LRFD desighn of Welds

    StructuralEIT Thanks for the answer, but don't bother. The steel spec. deals adequately with member thicknesses by requiring consideration of shear on net and gross sections and block shear etc. But what I'm talking about is where the weld filler material sticks onto the base material. Not...
  20. MarkAJohn

    LRFD desighn of Welds

    strguy11, Thanks for the reply. what exactly did the examples check? Shear yielding on the base material? Shear rupture in the weld material is: 0.75 x 0.6 x Fexx x sqrt(0.5) = 0.75 x 0.6 x 70 x 0.707 = 22.3 Shear yielding in the base material is: 0.9 x 0.6 x Fy = .09 x 0.6 x 36 = 19.44...

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