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  • Users: Mike Mike
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  1. Mike Mike

    Shear Lag

    Hi all, what is the minimum weld length for tension members? We are designing a ton of welded knife plate connections for HSS10x10x1/4 tension and compression braces. The LRFD tensile capacity is 371k. The LRFD axial load is +-100k, so we only need (4) 6" long 3/16" fillet welds, and we only...
  2. Mike Mike

    Do these deck beams look stable to you?

    Do the dropped beams in the photos below follow the intent of the code? This seems to be industry standard deck construction, and there is pressure from contractors to go along, but I'm not a fan for 2 reasons: 1. The bottom of the beam is in compression where continuous over posts and wants to...
  3. Mike Mike

    Dimension randomly changes in autoCAD paper space

    Hi all, occasionally our Dim scale linear value randomly changes. Most dimensions on most layouts do not have issues. In the example screenshots below, the viewport scale is 3/4" to 1', so the correct Dim scale linear value is 16. The ~8' dim is correct. autoCAD randomly multiplies by 16 to get...
  4. Mike Mike

    Lateral soil spring values for embedded posts or piles

    What soil spring values would I assign to a finite element model assuming the following: Medium dense sand 120 pcf Below water table Friction angle 30 degrees Assume perfect elastic plastic behavior Focus on the elastic portion of the p-y curve at k4 Per the National Frame Building...
  5. Mike Mike

    What's the best way to generate specifications these days?

    For the past 8 years I've used Deltek masterspec and edited word documents to suit project specifics, but I'm wondering if there's a better way in terms 1. time consumption 2. license fees and 3. quality of specifications. Seems like there are a bunch of other paid options out there, although...
  6. Mike Mike

    Am I supposed to specify mortar type M, S, N, or O?

    Typically for CMU I just specify wall assembly compressive strength f'm on my structural drawings, which determines permissible combinations of block strength and mortar per TMS602-22 specification table 2. But ASTM C270 and other sources such as the article below indicate an inverse...
  7. Mike Mike

    How do I know what sulphate exposure class to assign to my concrete?

    I'm designing a handful of exterior concrete piers to support fence posts. There is no geotech report and no sulphate testing. Do I have to use S3 per ACI 318-19 19.3.1? Is there a map that indicates where sulphate issues are common? In the link below, Ron suggested USDA may have some info, but...
  8. Mike Mike

    ASTM C150 vs C595 cement

    What's the difference? I have a contractor requesting to use C595 instead of C150. Based on the 2 threads linked below, I gather that C595 has a lower carbon footprint, but we have less history/experience. My understanding is that Portland Cement C150 is a type of hydraulic cement and is often...
  9. Mike Mike

    Anchor Capacity in Clay Tile Wall

    I would like to anchor a steel plate to face of hollow clay tile unit with toggle bolts, collapsible screw sockets, self-clinching nails, epoxy screens, umbrella inserts, etc. as shown in the following images. One important check is face shell flexural tensile stress. Does anyone have a method...
  10. Mike Mike

    Which risk category (RC) are telecommunications structures?

    ASCE7-02 table 1-1 says "communications towers" are RC4. ASCE7-22 C1.5 appears to group "telecommunications centers" under RC3, although it could be written more clearly. ASCE7-22 figure C1.5-1 hints at RC2, since telecommunications structures are typically sparsely occupied, and a failure would...
  11. Mike Mike

    Is It Possible to Preservative and Fire Treat Wood?

    Hi all, is it possible to pressure treat and fire treat lumber in say an exposed above ground wood deck scenario? Here's what I think I know so far: My office has done hundreds of 5-story light frame buildings over the last decade and all my superiors say no, you can't pressure treat and fire...
  12. Mike Mike

    HSS Through Bolt Connection Equation Inconsistency in AISC?

    Hi again yall, Why does manual page 7-13 eq 7-15, Rn = 1.8nFydt, give me half the value of specification J7(a) eq J7-1, Rn = 1.8FyApb? I'm looking at AISC 360-10 14th edition n = number of fasteners d = fastener diameter Fy = yield strength t = design wall thickness Apb = projected area in...
  13. Mike Mike

    Data Center Equipment Access Walkway Live Load?

    Hi all, what is an appropriate live load for a data center walkway? Owner is adding large racks for servers, batteries, electrical, etc to an existing multi-story concrete building, and access is restricted to service technicians. I've already accounted for all the equipment. I just need to know...
  14. Mike Mike

    Wide Air Gap Between Brick Veneer and Backing

    Architect wants a 5" air gap between typical brick veneer and typical exterior wood stud wall. Non-seismic. Low wind. BIA recommends 4 1/2" max unless "rationally designed" (tech notes 28 and 44B). My specifications say ties must be "capable of withstanding a 100 lb load... without deforming...
  15. Mike Mike

    Why is a decrease in tension lap splice length not allowed for excess reinforcement?

    A situation that arises on many projects: contractor forgot U bars at column tops or installed them at the wrong elevation, poured columns, and then asks me for a correction. My intent is to transfer some moment between slab and column, and I frequently find my column tensile steel is like 5 or...
  16. Mike Mike

    Period of Wood Structure Calculated to Justify Lower Earthquake Loads

    Has anyone ever calculated the period of a 4 or 5 story wood structure by hand? I calculated a higher period by the Rayleigh method than by the approximate method (ASCE 7-10 12.8.2.1), and was able to reduce my loads by a factor of 1.7. Still double checking my numbers but is this typical in...
  17. Mike Mike

    Plate Crushing Contribution to Long Term Shrinkage in Typical Multi-Story Light Frame Wood Buildings

    Does anyone know a good source for how much vertical deformation occurs specifically due to wood studs loading plates? ASTM D245 establishes Fc perp by compressing a 2" wide steel plate on a 2"x2"x6" wood specimen and recording the stress at 0.04" deformation. NDS states the deformation at a...
  18. Mike Mike

    Soil Presumptive Load-Bearing Values per IBC 2018 table 1806.2

    I'm designing a sonotube footing for a large sign per IBC 1807.3: Embedded Posts and Poles, which references table 1806.2 for presumptive soil capacities. I understand everything in the IBC, but all of my software programs ask for a "Maximum Lateral Pressure Limit", defaulting to 1500psf. Does...
  19. Mike Mike

    Did ICC get it right? Fall protection per IBC 2018 1607.10.4

    IBC 2018 1607.10.4 "Fall arrest and lifeline anchorages. In addition to any other applicable live loads, fall arrest and lifeline anchor-ages and structural elements that support these anchorages shall be designed for a live load of not less than 3,100 pounds (13.8 kN) for each attached...
  20. Mike Mike

    Illinois won't accept my education toward my SE application

    I have a bachelor's in Physics from University of Wisconsin, a master's in civil (structural) from Marquette University, and 5 years work experience. Illinois said they would consider a bachelor's in civil from Marquette to be worth (4) years of experience, but they said a master's in civil...

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