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  • Users: ldeem
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  1. ldeem

    Weathering Steel vs HDG

    I work in mining and am in the process of designing a replacement 90' truss. This is a limestone facility and the truss will be part of material handling system. Corrosion is a significant problem at the site. In the past we have used a lot of HDG but that can be hard to do on larger trusses...
  2. ldeem

    Two machines on same structure - combined vibration question

    I have a structure with two vibrating screens (14.4 Hz and 16.6 Hz) they are on separate levels but share columns. We are having a lot of trouble with one screen but no one has been able to find vibration reading that show a problem. My question is how do the vibration forces combine from two...
  3. ldeem

    Hydraulic Cylinder Stroke Length

    I am working on a project to add hydraulic cylinders to move large steel deflectors in bulk material handling chute. I know the actuator arm length and positions so I can find the required cylinder stroke length, which is around 30". My question is when specifying the cylinder stroke length is...
  4. ldeem

    Springs in Series

    I am dealing with a problem where I have a aggregate processing steel structure and the vibrating screen has been switched out for a unit with much higher dynamic loads. This has resulted in excessively high vibrations in the structure which is affecting the screen. The screen sits on its own...
  5. ldeem

    Stainless Steel Bellows or Fabric Expansion Joint Outdoor - Best Option?

    I am redesigning a kiln duct leg that runs to an ID fan. The kiln is used to fire limestone to make quick lime. The duct section is after the cooler and just before the ID fan. Temp is 815 F carrying dust laden air (bag house is after the ID fan). I am good the the thermal movements I have...
  6. ldeem

    Processing structure bar grating and deck plate vibration

    I have a project where the vibrating equipment (screen) was upgraded to a larger unit. The frequency is about the same but the dynamic forces are 5 times higher. During design I focused on keeping the main structure frequencies away from the vibrating equipment. This has worked and the structure...
  7. ldeem

    Bulk Material Conveyor Install Tolerances

    I am wondering what other folks here use as overall installation tolerances for bulk material belt conveyors. I am familiar with CEMA standards of 1/8" over 40' straightness and +/- 1/4" of level. I have interpreted these in the past as overall tolerances from tail to head pulley relative to the...
  8. ldeem

    Offset Loading of Silo

    I am working on a project to add a new circuit to the top of a 50’ diameter 110’ tall concrete silo. Client has asked about installing a stone ladder (material is hydrated lime) on the side wall. The original design is center loading of the silo and I think moving the loading to the side wall...
  9. ldeem

    Tension Field Action - End panels in Old Codes

    I am working on a power plant project with some deep plate girders designed back in 1976 (or before). From the drawing reactions and loads I have determined the original engineer must have considered tension field action for the shear capacity. The issue I have is that several of the plate...
  10. ldeem

    Mounting Pillow Block Bearing

    I am mounting large pillow block bearings to steel structure for a bulk material conveyor. Questions have come up regarding the proper bolt torque. To calculate the bolt torque I am starting with the horizontal bearing load, dividing by the friction coefficient to determine the normal (clamping...
  11. ldeem

    National Building Code 1967 - snow loading

    Can anyone send me a copy of the 1967 National Building Code snow load provisions? I am checking a roof for new ventilation fans and the current snow loads (drift and rain on snow surcharge) are not working very well.
  12. ldeem

    Screw Feeder Experience with Limestone Dust

    I am working on a project to relocate a truck loading chute about 20' from its current position under a storage bin. The client suggested a rotary airlock to screw conveyor to truck loading chute. After looking at screw conveyors I was thinking of screw feeder (eliminate rotary air lock)to truck...
  13. ldeem

    Corrugated Pipe Reclaim Tunnel

    I am designing a corrugated (Multi-Plate) pipe escape tunnel and conveyor tunnel. The new pipes are larger than the existing. I am comfortable with sizing the pipe and the hopper opening. My question is regarding the end of the pipe where it meets the existing concrete vault. The pipe will slope...
  14. ldeem

    Rock Anchor Loads

    I am a structural engineer and have done some small underground projects. I have seen a lot of equipment (mostly light weight) hung from the mine roof. I have always wondered about the capacity of the anchors. The contractors and maintenance all tell me the capacity is the DAG bolt capacity (10'...
  15. ldeem

    Pack rust changes in volume

    I have a project where a building parapet has been lifted up about 3/8" due to pack rust between steel roof beams and there bearing plate. It's a masonry building about 90 years old. The parapet cap has leaked for years which has caused the rusting. My question is once the water leakage has...
  16. ldeem

    Laterally loaded pile Py and STAAD

    I am working on a method to use STAAD for lateral pile analysis using multilinear soil springs. I have written a spreadsheet to create the py curves and spring constants for a pile in sand (I am using API RP-2A method). The STAAD model is working and seems to be creating reasonable results...

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