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  1. DaveAtkins

    Roof Collapse in Madison Wisconsin

    https://www.fox6now.com/news/woodmans-roof-collapse-madison-video I am guessing a ponding failure. I lived in Madison many years ago, and I believe this is an older building. Roof may not have been designed for ponding.
  2. DaveAtkins

    P-Little Delta

    I use RISA-3D for structural analysis. In the Help documents, it says you can account for P-little delta by dividing the columns into four segments vertically. Does this mean you need not bother with the B1 multiplier from AISC Appendix 8? DaveAtkins
  3. DaveAtkins

    Typical Anchor Bolt Projection

    I am working on a project where anchor bolt projection is a critical dimension. These are on grade bus stop platforms, where the custom designed shelter (designed by me, not an off the shelf shelter) will be anchored to a mat footing on grade, after which a topping slab containing a snow melt...
  4. DaveAtkins

    Crack in Bridge Crane Runway Support Beam

    One of our clients recently had repairs done to a crack in a bridge crane runway support beam. We have been hired to determine what caused it, and if upgrades are required. I have been told the crack was not at midspan. I have a few questions: * My first assumption with a crane runway...
  5. DaveAtkins

    Working in Metric

    For the first time in my career, I will be working on a project which requires the use of metric (hard metric at that!) units. I am curious about the experience of those who normally work with imperial units like I do. My hunch is I should not try to convert units back and forth, but instead...
  6. DaveAtkins

    Horizontal Crack in Residential Basement Wall

    I have inspected numerous residential basements, but I observed something recently that has me puzzled. See the attached photo. Normally, I see hairline, VERTICAL shrinkage cracks in basements. They are almost inevitable, and are rarely a concern. Horizontal cracks generally ARE a concern...
  7. DaveAtkins

    Surcharge Caused by Railway Spur

    I am checking a sheet pile bulkhead along a river, with a railway spur in the active zone. Does anyone have a reference for the surcharge (PSF) to use for analysis? DaveAtkins
  8. DaveAtkins

    Welded-Welded Single Plate Shear Connections

    I am working on a project where some of the floor beam connections have been installed incorrectly--single plate shear tab welded to BOTH the supporting girder and the supporting beam. Of course, the contractor is asking me if this is acceptable--my first response was no, since there has been...
  9. DaveAtkins

    Grout Made with River Water

    I am working on a project where diagonal soil anchors are being used to restrain the top of a steel sheet pile bulkhead along a river. The contractor has asked if he can use water from the river as mix water for the grout which will be used in the soil anchors. We had the water tested, and it...
  10. DaveAtkins

    SDC A

    I have recently "inherited" a couple of projects from co-workers who have left to pursue other opportunities. Both are in the construction phase, so I am just reviewing shop drawings and answering field questions. Both projects are in SDC A. However, on the Design Loads sheet for each...
  11. DaveAtkins

    Ideas for a Dissertation

    The recent thread on 1-1/4" guardrail posts started me thinking. It would be nice if a PhD student would write a dissertation on all of those structural engineering situations we face which are difficult to prove by the numbers. I can think of two right away: The aforementioned guardrail...
  12. DaveAtkins

    Standing Seam Metal Roof Canopy

    I am currently designing a standing seam metal roof canopy. Yes, I did provide a wide rib steel roof deck below the standing seam roof, so no diaphragm issues. The support framing is structural steel (curved beams), on steel tube columns, on concrete piers and footings. It is a stand alone...
  13. DaveAtkins

    Shear in a Basement Wall

    Assume Vu at the bottom of a basement wall exceeds phi*Vn. I contend that the only way to make the wall adequate is to make the wall thicker. But I have seen more than one engineer try to justify a wall that is too thin by checking shear friction in the wall, using the available vertical...
  14. DaveAtkins

    AISC Second Order Effects

    I confess I have been slow to transition from the AISC 9th Edition to the more recent editions (but I am working on it!). I have a copy of the 14th Edition, and am learning how to account for second order effects. It appears there are four options available: * Direct Analysis Method *...
  15. DaveAtkins

    Designing for F5 Tornado

    I am working with a client who is wondering what would be involved in creating a "tornado shelter" within a new building. The client thinks the locker rooms within the building could be designed as a tornado shelter. We originally proposed that the locker room CMU walls be designed as exterior...
  16. DaveAtkins

    Corrosion of Stainless Steel

    I have a client who is wondering why some of their stainless steel guardrails/handrails are showing signs of surface corrosion after one winter. These are exterior guardrails. The stainless steel is Type 304, with a light sandblasted finish. DaveAtkins
  17. DaveAtkins

    Equivalent Lateral Force Procedure

    I am confused by Equation 9.5.5.2.1-1 in ASCE 7-02. This equation states that Cs = SDS/(R/I), "when the fundamental period of the structure is computed." First of all, fundamental period does not enter into this equation, so why does it matter? Second of all, does this mean that in order to...
  18. DaveAtkins

    Why Are Open Web Joist Member Sizes Such a Mystery?

    I am checking an exisitng open web steel joist roof for a suspended drywall ceiling. I am sure it will not be a problem, but the local building inspector insisted that a check be done. My client, the ceiling installer, did everything the right way, hanging the ceiling at the joist panel...
  19. DaveAtkins

    Drilled Pier with Lateral Loads

    I am designing a drilled pier which supports one of those high mast lights at a weigh station along the interstate. So, in addition to vertical load, I have a lateral load and moment at the top of the pier. The Geotechnincal Report gives me a modulus of horizontal subgrade reaction, which...
  20. DaveAtkins

    Reinforcing Steel Braced Frame Diagonal

    I am working on a high rise addition, where the two upper floors of the existing high rise have braced frames. The diagonal members in these braced frames are overstressed when the addition loads are added. The diagonal is a W18X143. I find that addding a C10X30 to each flange will increase ry...

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