Design of Crane Runways According to CSA and CMAA

23-04-19 Design of Crane Runways According to CSA and CMAA by Victoria Lake

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Design of Crane RunwaysAccording to CSA and CMAA

By: Victoria Lake


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Outline

IntroductionTypes of RunwaysTypical SectionsCSA StandardsCMAA StandardsCrane ClassesTypes of LoadsLoad CombinationsExampleConclusion


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Introduction

Runway is beam that supports crane bridge and trolley

Should be stiff to limit deflections

Special Considerations Laterally unsupported, except at the

columns Subject to impact Unsymmetrical bending due to

lateral thrust from starting/stopping of crane trolley

Longitudinal loads due to starting/stopping of crane bridge

Greater Risk of Fatigue due to repeated loadings

RUNWAY BEAMS


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Types of Cranes

Under RunningTop Running


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Common Runway Beam Sections

(a) wide flange rolled section

(b) wide flange with added plate to top flange

(c) wide flange with added channel to top flange

(d-h) other variations

(i) horizontal truss


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Manufacturer and Client Data

Manufacturer to provide: Maximum wheel loads Wheel spacing Trolley weight Clearances required

Client to provide: Span Capacity needed Type of crane preferred Length of runway


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CSA Standards

Limit States Design per CSA S16-01

Appendix C: Crane Supporting Structures

Deflection Vertical, capacity > 225kN, L/800 Vertical, capacity < 225kN, L/600 Lateral, L/600

New Publication CISC: Crane Supporting Steel

Structures (2005) Provides more detailed procedures

and requirements


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CMAA Standards

Based on Allowable Stress Design

Procedure checks Allowable stresses Combined stresses Buckling, local and lateral torsional Longitudinal, vertical and diaphragm

stiffeners

Deflection is limited to 1/600 length of the span

Camber not to exceed 1/888 length of the span


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Crane Classes (from CMAA and CSA)

Crane Class

Load Cycles (1000’s)

Lifts (/hr) Capacity Speed

Class A

Standby

0–100 1> 0 – occasional full rated capacity

Slow

Class B Light

20–200 2-5 Light, 0 – few full rated capacity

Slow

Class C Moderate

20–500 5-10 50% rated capacity, >65% full capacity

Moderate

Class D Heavy

100–2000 10-20 >50% rated capacity Fast

Class E Severe

500–2000 >20 At or near rated capacity

Fast

Class F Continuous

>2000 continuous 100% rated Continuous


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Principal Loads

Dead Load (DL) weight of all elements of the

bridge structure, the machinery parts and the fixed equipment supported by the structure

Trolley Load (TL) Weight of trolley and any

equipment attached to it

Lifted Load (LL) The lifted load is the sum of the

working load and the lifting devices used for handling and holding the load, for example the load block, lifting beam, bucket, magnet, and grab

Vertical Inertia Forces Forces due to the motion of the

crane or crane components Forces due to lifting of the hoist

loadDead Load Factor (DLF)

applied the dead loads of the crane, trolley, and its associated equipment

Related to travel speed Hoist Load Factor (HLF)

applied to the motion of the rated load in the vertical direction

Also inertia forces and the mass forces due to sudden lifting of the hoist load


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Principal Loads, cont…

Inertia Forces From Drives (IFD), also referred to as Side Thrust

Forces from acceleration, deceleration, trolley impact with end stop

Applied to both live and dead loads

CMAA: Lateral load is calculated as a percentage of the vertical load, 7.8 times the lateral acceleration or deceleration rate ( > 2.5% of the vertical load)

CISC: 20% of combined weight of lifted load and trolley (for cab-operated cranes)


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Additional Loads

Operating Wind Load (WLO) outdoor crane is 5 lbs/ft2 of the

projected area of the crane with is exposed to wind

should be divided equally between the 2 girders

Forces due to Skewing (SK) horizontal forces normal to the

rail from wheels obtained multiplying the vertical

load exerted on each wheel by coefficient Ssk which depends upon the ratio of the span to the wheel base

0.03

0.05

0.07

0.09

0.11

0.13

0.15

0.17

0.19

2 3 4 5 6 7 8

Ssk

SPANRATIO

WHEELBASE


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Extraordinary Loads

Stored Wind Load (WLS) maximum wind load that the

crane can withstand when it is not in service

depends on the height of the crane above the ground, its geographical location, and its degree of exposure to prevailing winds

Collision Forces (CF) Resulting from crane hitting

bumper stopsTorsional Forces and Moments

Starting/stopping of bridge motors

Due to vertical loads Due to lateral loads


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CMAA Load Combinations

Case 1 regular use under principal

loading (stress level 1)

Case 2 regular use under principal and

additional loading (stress level 2)

Case 3 Subject to extraordinary loads

(stress level 3) applies mostly to outdoor cranes

Out of Service Wind

In collision

Test Loads

DL(DLF )+TL(DLF )+LL(1+HLF)+IFDB T

DL(DLF )+TL(DLF )+LL(1+HLF)+IFD+WLO+SKB T

DL+TL+WLS

DL+TL+LL+CF

Not more than 125% rated load


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CISC Load Combinations

(vertical + side thrust)

(C1 + impact + longitudinal)

(vertical for multiple cranes + side thrust + long.)

(vertical + side thrust + long., all multiple cranes)

(vertical + side thrust + impact + long., all multiple)

(vertical + side thrust, all multiple)

(vertical + side thrust + bumper impact


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Example: Design Mono-symmetric Runway Beam

INPUT

Span irs = = 10670 mmNumber of Cranes, Each Runway ncr = = 1Crane Hook Capacity - Number of Hook(s) each nh = = 1Crane Hook Capacity - Capacity each hook ch = = 22.68 tonnesWeight of Crane Trolley wct = = 2721 kgBridge Wheels per Rail - Total Number nbwr = = 2Bridge Wheels per Rail - Driven nbwd = = 1Bridge Wheel Spacing bws = = 3050 mmMin. Distance Between Wheels of Crane in Tandem dbwt = = 169 kNCrane Rail - Description crd = = 89 mmCrane Rail - Self Load crsl = = 19.8 kg/mDeflection Criteria - Vertical Limit (one crane, not including impact) dcvl = irs/600 = 17.783 mmDeflection Criteria - Horizontal Limit dchl = irs/400 = 26.675 mm

Lifted Load ll = (ch*1000)*9.81/1000 = 222.49 kNTrolley Load tl = wct*9.81/1000 = 26.69 kN


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Example: Load Diagram


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Example: Determine Moments and Side Thrust

CALCULATIONS

MOMENTS

point of max. bending moment pmbm = 0.5*(irs-bws/2) = 4572.5 mmleft reaction lr = (dbwt*(irs-(pmbm+bws))/irs)+(dbwt*(irs-pmbm)/irs)= 144.85 kNright reaction rr = (dbwt*(pmbm+bws)/irs)+(dbwt*(pmbm/irs)) = 193.15 kNMLL, under wheel load closest to mid-span mll = lr*pmbm = 662.31 kN-m

moment due to impact mdi = 0.25*mll = 165.6 kN-mestimated dead load, including rail and conductors edl = = 2.64 kN/mMDL mdl = (edl*(irs/1000)^2)/8 = 37.57 kN-m

Mfx, factored moment mfx = 1.25*mdl+1.5*(mll+mdi) = 1288.79 kN-m

SIDE THRUST

side thrust st = 0.2*(ll+tl) = 49.84 kNside thrust, per wheel stpw = st/4 = 12.46 kNratio of side thrust to max. wheel load rstwl = stpw/dbwt = 0.0737specified moment due to side thrust, MH mh = rstwl*mll = 48.83 kN-m

factored moment due to side thrust, MHF mhf = 1.5*mh = 73.24 kN-m


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Example: Select trial section

SELECT TRIAL SECTION

Ix1 Ix1 = = 2.00E+09 mm4

vertical deflection, based on Ix1 delta1 = = 18.5 mmless than allowable? delta1<dcvl = FALSEIx needed? based on vertical deflection ixr = (delta1/dcvl)*Ix1 = 2.081E+09 mm4

Iy needed? based on horizontal deflection iyr = (delta1/dchl)*rstwl*Ix1 = 1.023E+08 mm4

In this case, W610x217 with a 381x12.7 cover plate is chosen


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Example: Subsequent Procedure

After selection of trial section, the procedure is as follows:

Check class of section (S16-01, Clause 11.2)

Calculate plastic moment, Mp, and plastic section modulus, Z

Calculate elastic section properties (built-up)

Calculate section properties for mono-symmetric analysis (not covered in CSA, use CISC Section 5.9)

Check strength of section in bending

Calculate limiting unbraced length for plastic bending capacity and inelastic buckling

Calculate factored resistance Calculate distribution of side thrust Check overall member strength Check stability (lateral torsional

buckling)

Completes check for bendingNext:

Design stiffeners Design bearings and lateral

restraints Design connections (welds and

bolts) Check fatigue resistance


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Conclusion

Complicated procedure

Must design a stiff runway to prevent deflections

Also consider potential for fatigue due to repeated loading

Which standards to follow: CSA or CMAA?

CISC’s new “Guide to Crane Supporting Structures” provides good examples and information


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Design of Crane Runways According to CSA and CMAA