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CRANE RUNWAY BEAM DESIGN - AISC LRFD 2010 and ASD 2010          

Crane runway design based on           Code Abbreviation
AISC 360-10 Specification for Structural Steel Buildings AISC 360-10
AISC Design Guide 7: Industrial Buildings-Roofs to Anchor Rods 2nd Edition AISC Design Guide 7
Crane runway beam section Label
Section Properties                  
Label                  
  A = Label [in2]        
  d = Label [in] bf = Label [in]  
  tw = Label [in] tf = Label [in]  
  h = Label [in] h0  = Label [in]  
  top yc = Label [in] bott. yt = Label [in]  
  Ix = Label [in4] Iy = Label [in4]  
  top Sxc = Label [in3] bott. Sxt = Label [in3]  
  Sy = Label [in3]          
  Zx = Label [in3] Zy = Label [in3]  
  rx = Label [in] ry = Label [in]  
  J = Label [in4]  Cw = Label [in6]  
Top Flange                  
  Af = Label [in2] dall / Af = Label [in-1]  
  rT = Label [in] ryt = Label [in]  
  It = Label [in4]          
  St = Label [in3] Zt = Label [in3]  
                   
W section yield strength Fwy = Label [ksi]          
Cap channel or plate yield strength Fcy = Label [ksi]          
Runway beam unbraced length Lb = Label [in]          
Design Forces     LRFD-10       ASD-10    

Bending moment x-x axis Mx  = Label [kip-ft]  Mx = Label [kip-ft]  
Bending moment y-y axis - top flange My-t = Label [kip-ft] My-t = Label [kip-ft]  
Bending moment y-y axis - bottom flange My-b = Label [kip-ft] My-b = Label [kip-ft]  
Shear along y-y axis  Vy = Label [kips] Vy = Label [kips]  

Conclusion                  
      LRFD-10       ASD-10    

Overall ratio = Label Label ratio = Label Label  

Local buckling               Label  
Bending about the X-X axis  ratio = Label Label ratio = Label Label  
Bending about the Y-Y axis in the top flange - top running crane ratio = Label Label ratio = Label Label  
Bending about the Y-Y axis in the bott flange -underhung crane ratio = Label Label ratio = Label Label  
Label  ratio = Label Label ratio = Label Label  
Shear along Y-Y Axis  ratio Label Label ratio = Label Label  
Web sidesway buckling  ratio Label Label ratio = Label Label  

Runway beam vertical deflection         ratio = Label Label  
Runway beam lateral deflection         ratio = Label Label  

Design Basis & Assumption                 Code Reference
1. The crane runway beam is designed as simple span beam. AISC Design Guide 7
2. The W section top flange and cap channel resist the hor. load and the combined section resists the ver.
    load. This assumption eliminates the need for an analysis of torsional effects on the combined section
    and simplifies the analysis.
Section 18.1 on Page 56
2. For underhung crane the hor. side thrust load is all taken by the W or S shape bottom flange.
    This assumption eliminates the need for an analysis of torsional effects on the combined section and
    simplifies the analysis.
Section 18.1 on Page 56
3. If A36 channel cap is used on A992 W section then lateral torsional buckling and weak axis flexure
    strength must be calculated based on A36 yield stress.
Section 18.1.4 on Page 57
4. For bending moment about the X axis, the moment caused by runway beam and rail self weight is
    calculated at beam midspan as maximum and added to the maximum moment caused by crane
    moving load. Even though the maximum moment caused by crane moving load may not be at the
    beam midspan, this conservative approach rarely makes a significant change in the final combined
    Mx value used in the runway beam design.
 

CALCULATION                  
Check Local Buckling                  
W Shape Classification                  
Flange of W shape                 AISC 360-10
Compact limit lp = 0.38 sqrt (E / Fwy) = Label   Table B4.1b Case 10
Noncompact limit lr = 1.0 sqrt (E / Fwy) = Label    
  bf / 2tf = Label       Label  
Web of W shape                  
Compact limit lp = 3.76 sqrt (E / Fwy) = Label   Table B4.1b Case 15
Noncompact limit lr = 5.7 sqrt (E / Fwy) = Label    
  h / tw = Label       Label  
W shape classification             Label  
Label     Label       Label  
                   
Check Bending about X-X Axis                  
Mn - Compression Flange Yielding         AISC 360-10
  Mn1 =   Mp = Fy Zx = Label [kip-ft] Eq F2-1
                 
Mn - Lateral Torsional Buckling         AISC 360-10
Moment gradient                  
  Mmax = Label [kip-ft] M at L/4  MA = Label [kip-ft]  
M at 2L/4  MB = Label [kip-ft] M at 3L/4  MC = Label [kip-ft]  
  Cb = = Label   F1-1
For underhung crane, increase Cb by multiplying 1.4 Cb = min( Cb x 1.4 , 3) = Label    

Runway beam unbraced length Lb =     = Label [in] AISC 360-10
  Lp = = Label [in] Eq F2-5
  rts = = Label [in] Eq F2-7
  Lr = Eq F2-6
        = Label [in]  

For Lb <= Lp             AISC 360-10
  Mn2 = Not Applicable = NA [kip-ft] F2.2 (a)
For Lp < Lb <= Lr               AISC 360-10
  Mn2 = Eq F2-2
          = Label [kip-ft]  
For Lb > Lr               AISC 360-10
  J = Label [in4]          
  Fcr = = Label [ksi] Eq F2-4
  Mn2 = Fcr Sxc <= Mp = Label [kip-ft] Eq F2-3
                 
Mn - LTB Mn2 =     = Label [kip-ft]  
                 
Mn - Compression Flange Local Buckling         AISC 360-10
  l = Label          
  lpf = Label lrf = Label    
For lpf < l <= lrf                
  Mn3 = = Label [kip-ft] Eq F3-1
                 
Mn - Bending about X-X Axis          
  Mnx = Label = Label [kip-ft]  

LRFD 2010 Mx = Label f = 0.9    
  ratio = Mx / (f Mnx)   = Label Label  

ASD 2010 Mx = Label W = 1.67    
  ratio = Mx / ( Mnx / W )   = Label Label  

                 
Check Bending about Y-Y Axis               AISC 360-10
For top running crane, top flange is checked for bending about Y-Y axis  
Check top flange compactness, for W check W flange only, for W+Cap Channel check both W and
Channel flange
 
Top flange compactness   = Label        
For compact top flange Mny = Fy Zt <=1.6Fy Sy = Label [kip-ft] Eq F6-1
For noncompact top flange              
   Mp = Label [kip-ft] Sy = Label [in3]  
  l = Label          
  lpf = Label lrf = Label    
  Mny = = Label [kip-ft] Eq F6-2

LRFD 2010 My-t = Label f = 0.9    
  ratio = My-t / (f Mny)   = Label Label  

ASD 2010 My-t = Label W = 1.67    
  ratio = My-t / ( Mny / W )   = Label Label  

For underhung crane, bottom flange is checked for bending about Y-Y axis  
Bottom flange compactness   = Label        
For compact bottom flange Mny =  Fy Zb <=1.6 Fy Sb = Label [kip-ft] Eq F6-1
For noncompact bottom flange                  
   Mp = Label [kip-ft] Sy = Label [in3]  
  l = Label          
  lpf = Label lrf = Label    
  Mny-b = = Label [kip-ft]  Eq F6-2

LRFD 2010 My-b = Label f = 0.9    
  ratio = My-b / (f Mny)   = Label Label  

ASD 2010 My-b = Label W = 1.67    
  ratio = My-b / ( Mny / W )   = Label Label  

             
Check Biaxial Bending on Top Flange - compression in top flange           

LRFD 2010     Mx / (f Mnx) + My-t / (f Mny) = Label Label Eq H1-1b

ASD 2010     Mx / (Mnx /W)  + My-t / (Mny /W) = Label Label  

Check Biaxial Bending on Bottom Flange - tension in bottom flange            

LRFD 2010     Mx / (f Fy Sxt) + My-b / (f Mny) = Label Label Eq H1-1b

ASD 2010     Mx / (Fy Sxt /W) + My-b / ( Mny /W) = Label Label  

                 
Check Shear along Y-Y Axis           AISC 360-10
Clear dist between trans. stiffeners a = Lb     = Label [in]  
W sect clear dist between flange h = Label [in] a / h = Label    
  h / tw = Label            
  kv = 5 if h / tw < 260 = Label   G2.1 (b)
      5 if a / h>3.0 or a / h>[260/(h / tw)]2        
      5 + 5 / (a / h)2        
  T = sqrt(kv E / Fy) = Label    
For h / tw <= 1.10T                  
  Cv =     = Label   Eq G2-3
For 1.10 T < h / tw <= 1.37 T                  
  Cv = 1.10 x sqrt(kv E / Fy) / (h / tw) = Label   Eq G2-4
For h / tw > 1.37 T              
  Cv = 1.51 E kv / [ (h / tw )2 Fy ] = Label   Eq G2-5
  fVn = 1.0 x 0.6 Fy (d tw) Cv = Label   Eq G2-1

LRFD 2010 Vy = Label f = 1.0    
  ratio = Vy / (f Vn)   = Label Label  

ASD 2010 Vy = Label W = 1.5    
  ratio = Vy / ( Vn / W )   = Label Label  

                   
Check Web Sidesway Buckling           AISC 360-10
(h/tw) / (Lb/bf) = Label       Label
  limit state of web sidesway buckling not applicable Label J10.4 (b) (ii)
Yield moment My = Label [kip-ft]          

LRFD 2010                  
  Mu = Label [kip-ft]           
Label Cr = Label [ksi]          
  Rn = = Label [kips] Eq J10-7
  Pv-impt = 1.2xPbr + 1.6xPlt x a impact factor = Label [kips]  
  f = 0.85        
  ratio = Pv-impt / ( f Rn ) = Label Label  

ASD 2010                  
  Ma = Label [kip-ft]           
Label Cr = Label [ksi]          
  Rn = = Label [kips] Eq J10-7
  Pv-impt = Pbr + Plt x a impact factor = Label [kips]  
  W = 1.76          
  ratio = Pv-impt /( Rn / W)   = Label Label  

                   
Check Runway Beam Deflection           Code Reference
Crane serviceability criteria based on  
CISC Guide for the Design of Crane-Supporting Steel Structures 2nd Edition Table 4.1 item 14,15
AISC Design Guide 7: Industrial Buildings-Roofs to Anchor Rods 2nd Edition Section 18 on Page 56
CMAA 70-04 Specifications for Top Running Bridge and Gantry Type Multiple Girder Electric Overhead
Traveling Cranes
Clause 1.4.3
CMAA crane service class Label Label  
Ver deflection limit (no impact , max wheel load) Bv = Label  
Hor deflection limit (no impact , 10% max wheel load) Bh = Label  
Runway beam span L = Label [in]          
Vertical Deflection                  
Unfactored max ver. wheel load Pmax = Label [kips / per wheel] impact factor NOT included
  Ix = Label [in4]          
Max ver deflection Dmax = Label = Label [in]  
Allowable deflection Da = Lver / Bv     = Label [in]  
  ratio = Dmax / Da = Label Label  
                   
Horizontal Deflection                  
Unfactored max hor. wheel load Ph = Label [kips / per wheel]  
For top running crane, only top flange moment of inertia is considered for deflection check  
Top flange It = Label [in4]          
For underhung crane, only bottom flange moment of inertia is considered for deflection check  
Bottom flange Ib = Label [in4]          
Max hor deflection Dmax = Label = Label [in]  
Allowable deflection Da = Lhor / Bh     = Label [in]  
  ratio = Dmax / Da = Label Label