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Recent content by Shu Jiang PEng SE

  1. Shu Jiang PEng SE

    Ferry Dock Collapse

    Top chord out-of-plane stability is key for design this type of structure. Here is one example I prepared before. Different load capacities could be derived with different unsupported compression lengths (out-of-plane) specified in FEA. The structure is not same, but design principle is. In...
  2. Shu Jiang PEng SE

    Ferry Dock Collapse

    Top chord out-of-plane buckling could be the reason. vatical hanger and bottom chord do not provide enough lateral support stiffness to the top chord. What the unsupported length of the top chord is in you FEA simulation? Here is a post on LinkedIn which may help understand why the collapse...
  3. Shu Jiang PEng SE

    I need help with my confusion about modal mass participation ratios.

    Those modes with small mass participation factors are local vibrations. The local vibrations do not affect dynamic analysis and design f the structure as a whole. You can not model those members in your FEA to facilitate dynamic analysis. ————————————————————— Shu Jiang, SE (Nevada)...
  4. Shu Jiang PEng SE

    Bracing top flange of a W36 in SAP2000

    W beams were simulated with 1D element, X bracing between the beams can not be simulated in the fea model. You could specify beam lateral support distance equal to X brace spacing. And hand check brace angle strength and stiffness requirement per Aisc appendix 6. You have to simulate beam with...
  5. Shu Jiang PEng SE

    Mass Source for Seismic Excitation

    Not only dead load of structure and equipment, mass shall also include some percentage of live load in some cases. You may go back to ASCE 7 for more information regarding seismic design. ————————————————————— Shu Jiang, SE (Nevada). PE(Michigan, South Dakota), PEng (Ontario) J&J Structural...
  6. Shu Jiang PEng SE

    ASCE 7 wind pressure

    Figure 28.6-1 of ASCE7-10 show the wind load on wall and roof of low-rise building, ————————————————————— Shu Jiang, SE (Nevada). PE(Michigan, South Dakota), PEng (Ontario) J&J Structural Consulting Inc. Structural design, analysis, inspection, drawing review and stamping, and connection design
  7. Shu Jiang PEng SE

    Plate to round HSS connection - Punching shear inequality in AISC 360-10

    Ultimate shear stress is Fu/sqrt(3)=0.6Fu and shear yield stress is Fy/sqrt(3)=0.6Fy. The formula k1-3 is to guarantee the configuration of the connection geometry to ensure that the chord shear yield stress is larger than the plate ultimate shear stress. You can calculate the maximum allowable...
  8. Shu Jiang PEng SE

    Design of C-shaped and rectangular core walls

    Shear wall theoretically can resist shear in the plane of the wall only. You have treat the “C” shape wall as two section: the “web” take horizontal force in plane along the “web”; the “flanges” take the horizontal force perpendicular to the web only. Extra torsion due to the eccentricity of...
  9. Shu Jiang PEng SE

    Shear stress in a slab

    Check punch strength, conservatively treat the slab as one way slab and check bending and shear strength respectively. There would no worries if all the three items are acceptable. ————————————————————— Shu Jiang, SE (Nevada). PE(Michigan, South Dakota), PEng (Ontario) J&J Structural Consulting...
  10. Shu Jiang PEng SE

    Trolley Beam Hoist Structure Design

    The supporting structure normally be designed to take the marked trolley lifting load plus all related equipment/structure self weight. Appropriate load factors for each load is considered too. ————————————————————— J&J Structural Consulting Inc. Structural design, analysis, inspection, drawing...
  11. Shu Jiang PEng SE

    Thin concrete shell roof

    For your information. An 80 feet dimeter concrete tube with 4” thick wall. Investigate the maximum external buckling pressure of the tube can take. The maximum buckling pressure shall be q=3EI/R^3 (strength of materials: part II Advanced theory and problems – by S. Timoshenko). Assume the...
  12. Shu Jiang PEng SE

    MASS21 - use with or without the rotary inertia?

    You do not need to consider rotary inertia whenever the support is coincident with the (equipment (mass) rotation center. ————————————————————— J&J Structural Consulting Inc. Structural design, analysis, inspection, drawing review and stamping, and connection design
  13. Shu Jiang PEng SE

    Thin concrete shell roof

    The shell seems extreme thin per the dimension of the arc. Is this the right dimension? ————————————————————— J&J Structural Consulting Inc. Structural design, analysis, inspection, drawing review and stamping, and connection design
  14. Shu Jiang PEng SE

    column spirals

    “Plain bars are permitted only for spiral reinforcement used as transverse reinforcement for columns, transverse reinforcement for shear and torsion, or confining reinforcement for splices.” Yield strength less than 100ksi is normally acceptable. The tie diameter shall be determined by the...
  15. Shu Jiang PEng SE

    Wind load on trussed tower

    Use section 29.5 of ASCE 7 2010 calculate wind load. Apply the load to any member not being shielded in the leeward wind directions. ————————————————————— J&J Structural Consulting Inc. Structural design, analysis, inspection, drawing review and stamping, and connection design
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