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  • Users: dlew
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  1. dlew

    Question about spreader beam unbraced length

    CWT, For a more detailed discussion of a spreader beam unsupported length see Thread 507-38270.
  2. dlew

    Welding reinforcing plates to stressed members

    Hey Guys, Thanks for your fast response. Your comments and references were very useful and are appreciated.
  3. dlew

    Welding reinforcing plates to stressed members

    Hello! I am working in the reinforcement of an existing steel structure to carry additional loads. We are planning to add reinforcing plates to those members that need them. The existing dead load stress in those members is approximately 15 to 20 ksi. Live load is relatively small. The...
  4. dlew

    Suggest Books for Pre Engineered Steel Trusses Design

    pasachi, Pre-engineered steel trusses are designed by the fabricator. The designer specify on the drawings the critical dimensions and the loads. If you are only interested on the trusses, you could contact a joist girder fabricator. If they are interested in the job they would answer any...
  5. dlew

    Wind load Analysis on a Circular Building with a Dome Roof

    PurdueEng, Figure 6-16 of ASCE 7-02 gives the GCp coefficients for Domed Roofs for all heights of buidings.
  6. dlew

    "Rubber" Pad @ Truss Connection?

    jheidt2543, I think the purpose of the rubber pad is to make the truss-to-column connection a simple connection, and avoid a moment in the column due to the gravity loads. I assume the stability of the building for lateral loads is provided by other structural elements.
  7. dlew

    Steel Design to Structural Fiberglass

    auxblade, My experience designing with fiberglass elements, both hand-layon and structural extruded shapes, is limited to mechanical equipment as tanks, chimneys, etc. The degradation of the mechanical properties of the fiberglass with temperature and exposure to the environment need to be...
  8. dlew

    oil storage tank foundation design

    fritzee11, It is Irving Boberg's paper "Oil Tank Foundations", dated 1951! It only addresses gravity loads. I believe Boberg was the chief engineer of Chicago Bridge and Iron at that time. Regards AEF
  9. dlew

    Column Bracing

    CWT, Here is my two cents worth of thought. The 6" by 1/2" plates provide lateral support to each column about their weak axis from the crane girder down. The two columns are NOT braced about their strong axis by the plates. The critical buckling will be, then, about the...
  10. dlew

    Very Concerned - I may have underestimated load

    haynewp, I agree with you that the provision of 20 psf for partitions should be included in addition to the 50 psf live load (per ASCE 7).
  11. dlew

    Very Concerned - I may have underestimated load

    CTW, The ASCE 7 shows 4 subcategories for OFFICE BUILDINGS: File and Computer rooms Load based on equipment weight Lobbies and first floor corridors 100 psf Offices 50 psf Corridors above first floor 80 psf I would consider...
  12. dlew

    Rigid base plate design

    sc, In rigid base plates the tension in the anchor bolts is large, and that requires thick base plates and heavy welding of the column to the base plate. A type of base plate more appropiate for a rigid column base is shown on page 4-131 of the AISC's "Manual of Steel Construction&quot...
  13. dlew

    steel truss web member

    shei, Some thoughts about your problem: If the load on the truss remained the same, the axial force in the web members would increase 32%. The added back-to-back angles, if they are of the same size would double the capacity of the member, that is more than enough. Another way to reinforce...
  14. dlew

    Beam Deflection Question

    Anthonyc007, The book "Formulas for Stress and Strain" by Roark have formulas for partial uniform load on single span with different support conditions. I do not include the formulas here because they need a sketch. If you want to see the pertinent book page, let me know your...
  15. dlew

    allowable defelection

    Lufti, I would check two items: 1) That the distance from the deflected power lines (at maximum sag) to any not insulated object complies with the clearances specified on the Electrical Code. 2) That the frame is stiff enough not to produce a dynamic problem if the presence of wind...
  16. dlew

    Steel Column outside of Bldg Slab

    tw, You could analyze the entire column by substituting an equivalent spring for for each girder to consider the restraint of the girders. The spring constant to use is the lateral load at the free end of the girder that produce one inch displacement. The springs act in a direction...
  17. dlew

    Tension flange restraint

    mobe, The restraint of the tension flange provides some restraint to the compression flange through the bending strength of the web. This approach is commonly used in light-gage shapes as channels and Zees that support siding or roofing subject to reversal of wind loads. The book...
  18. dlew

    Truss uplift -- maybe, maybe not

    JBB2B, You have shown a lot of good information, but not enough. Some questions that come to mind are: 1) Is the separation between the ceiling and the non-bearing wall uniforme, or arched? If arched, what line is level, the ceiling or the top of the wall? 2) Where is the building...
  19. dlew

    U Bolts

    Lufti, There are formulas and tables to calculate the torque required to get a given tension in the bolt. For non-lubricated high strength bolts, 1/2" in diameter, an old AISC publication shows hat a torque of 90 ft-lbs is required to produce a tension in the bolt of 10,850 pounds...
  20. dlew

    Torsion capacity in existing RC beam

    SamEnella, The U-shaped stirrups provide shear/torsion reinforcement for the two sides and the bottom of the RC beam. The reinforcing bars in the cantilevered slab that extend through the top of the beam and are anchored (by hook or by development length) could take torsional shear stresses...

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