2. CONSULTING ENGINEERS LIMITED
Crane Classification
Classification as per Crane Manufacturers Association of America (CMAA)
1. Class A1 ( Standby Service )
2. Class A2 ( Infrequent Use )
3. Class B ( Light Service )
4. Class C ( Moderate service)
5. Class D ( Heavy Duty)
6. Class E ( Severe Duty Cycle Service)
7. Class F ( Steel Mill)
3. CONSULTING ENGINEERS LIMITED
Various Parts of Crane
1. Wheel Carriage
2. Crane Girder
3. Trolley or Crab
4. Hook
5. Crane Wheels
6. Gantry Girder
7. Crane Stops
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Loading Considerations
1. Vertical Loads
a. Weight of Crane Frame
b. Weight of Trolley or Crab
c. Hook Load
d. Impact Load
2. Horizontal Loads
a. Lateral (Surge) Load =
= (Hook Load + Trolley Weight) x µ x (No. of breaking wheels / No. of wheels)
= 10/100 (Hook Load + Trolley Weight) ……For EOT Crane
= 5/100 (Hook Load + Trolley Weight) ……..For Hand Operated Crane
b. Longitudinal (Drag/Tractive) Load =
= 5/100 (Hook Load + Trolley Weight)
5. CONSULTING ENGINEERS LIMITED
Selection Of Gantry Girder
Points to be checked :
1. Generally, Single-span gantry girders are desirable.
2. Abrupt changes in c/s should be avoided & proper camber should also be
provided.
3. Cantilever gantry girders should be avoided.
4. Deflection should be limited to as per Table-6 of IS:800-2007
5. Rail eccentricity over the gantry girder should be avoided as far as possible.
6. Stiffeners should be welded to underside of the top flange & down web.
7. To resist lateral loading, the strength of the top flange alone should be
considered.
8. Generally, continuous welds shall be provided for connecting additional
members to the rolled beams used as gantry girders considering fatigue factor.
9. For economic design, depth of gantry girder should be about 1/12th of the span
& that width of flange should be 1/40th to 1/30th of the span.
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Structural Stability Considerations
1. Girder Section Properties
-Web of section
-Top flange
-Bottom flange
2. Columns
-Arrangement/system of columns for load transfer from crane to base.
- Orientation of columns
3. Bracings
-Sections to be used : Mostly double angles
-Location of bracings
-Bracings system
4. Crane Stops
Crane stops are used to prevent the crane moving past the end of a runway, thereby
preventing the crane from falling off.
-Energy absorbing fixtures shall be used.
-Expansion gap of 25 mm is kept in a continuous rail at every 30m length.
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Load Combinations
For SERVICEABILITY
a. DL + LL + EQPL
b. DL + LL + EQPL ± WL
c. DL + LL + EQPL ± 0.8EL
For DESIGN
a. 1.5DL + 1.5LL + 1.5EQPL
b. 1.2DL + 1.2LL + 1.2EQPL ± 1.2WL
c. 1.2DL + 1.2LL + 1.2EQPL ± 1.2EL
d. 0.9DL ± 1.5EL
11. CONSULTING ENGINEERS LIMITED
Design Of Gantry Girder
(IS 800 : 2007)
1. Calculating max. Wheel Load from analysis data.
2. Calculating max. BM = (Due to Self Weight of Crane ) + (Due to max. Wheel Load with Impact)
= 2Wc (L/2-c/4)2 / L
1. Calculating max. Shear Force = WL (2-c/L) : Clause 8.4
2. Selection of Girder Section
3. Calculating combined section properties & finding class of section
4. Calculating moment capacity of section
5. Check for Buckling Resistance, Shear, Bi-axial Bending & Deflection : Section-8, 9
6. Check for fatigue resistance : Section-13
12. CONSULTING ENGINEERS LIMITED
Design Of Gantry Girder
(Some design considerations)
1. If factored design force exceeds 0.6 times design shear strength of girder, then moment due to
lateral torsional buckling will come into picture & design moment capacity should be worked
out w.r.t. clause 9.2
2. Shear lag effect in flanges may be disregarded as per clause 8.2.1.5
3. Effective length for lateral torsional restraint provided as intermediate lateral restraints, shall be
taken as 1.2 times length between lateral restraints. Otherwise, when beam is continuously
restraint for full length, effective length shall be taken in accordance with the Table-15.
4. Resistance to shear buckling shall also be verified as per clause 8.4.2
