Dubai Technical dept.
Date
Project:Job No.
Safe Working Load, SWL Tons
Spreading Length metres
Safety Factor in Compression
Yield stress of the Beam material MPa
Allowable Tensile Stress MPa
Elastic Modulus of the material MPa
SWL, W = 1109.7 kN 10.000 metres a = 60.0 Degrees 637.9 kN y x 318.9 kN x 10.000 metres W/2 = 552.4 kN W/2 = 552.4 kN Tie Length = L = 112.6 150
Geometry of Lifting, Solved using the equations of Static Equillibrium
12/5/2013
240
Belleli Energy srl, Dubai Branch
10.000 1.6
prepared by
DESIGN OF SPREADER LIFTING BEAM of Hollow Circular Cross Section
Spreading Length, L = Compressive Force, C =
Tensile Force, P = Hitachi Zosen, Arzew Plant, Algeria "BLOCK-E"
4776
R. Venkat
210000
As the Spreader beam is free for all its three planar DOF (x,y & Rz Degrees Of Freedom) at the nodes of application of load, The bar behaves like
a TRUSS member and it will resist only the AXIAL force (here, Compression) and it will NOT resist BENDING in the plane.
This Spreader Beam is a typical case of Timoshenko's BEAM-COLUMN (Horizontal members having axial loads in addition to lateral loads) with both the ends HINGED. The Elastic Instability in the lateral direction causes the Spreader beam to BUCKLE due to the SLENDERNESS. This imposes the limitation on the Compressive load. The load at which the TRANSVERSE BUCKLING commenced is the CRITICAL load (Pcr).
A
B
Dubai Technical dept.
2) the horizontal component of resolved P induces a compressive force C in spreader beam, hence
P * Cos a = C
Compressive Force in Beam C = 318.9 kN
C * FOS sallow = 3401.91 mm2 8" Sch20 219.1 8" Sch20 as perAPI 5L 323.80 mm 6.35 mm 6332.85 mm2 8.0E+07 mm4 112.26 mm 49.71 kg / m
Compressive Strength of the pipe selected = X
= sallow*As
Cactual = 949.93 kN
Cactual
C
nc = 2.98 Nr.
For both ends HINGED members, the EFFECTIVE length equals the LENGTH of the member
L/r = 89.08 Nr.
2p2 E sy
Cc = 131.42 Nr.
Computing the factor, FS = (5/3) + (3/8) * [(L/r) / Cc] - (1/8) * [(L/r) / Cc] 3
FS = 1.88 Nr.
Allowable Stress in intermediate buckling sallow(ib) = (sy/Fs) * [1 - (1/2) * {(L/r) / Cc} 2
]
s 98.23 MPa
More than Euler's Critical Range
Calculations for the Intermediate-block, Pls. ignore for the Slender Range
Compressive Force in Newton X Safety Factor in Compression
Cross section area OD of the Pipe
A
Moments of Inertia, Ixx=Iyy=I=
Allowable Stress
Allowable Stress in Mpa
Tk of the Pipe
SATISFACTORY
= Cc The Crippling commencement factor,
OK *** Beam in the Intermediate-block, COMPRESSION & BUCKLING analyses needed ***
= = Minimum Area of Cross section required in mm2
Load Factor is OK Signal Box "SAFE
DESIGN"
Cross section Area, As
Radii of Gyration, rx=ry=r=
Safety Margin is OK
Buckling Stress is OPTIMUM
Safety Margin is OPTIMUM
12" Sch20 Minimum Area of Cross section required in mm2
= Slenderness Ratio (L/r)
(B) Design for Elastic Stability - Transverse Buckling [1]
OPTIMUM
Effective Length of the Spreader Beam Radius of gyration
Buckling Stress is OPTIMUM
Load Factor is OPTIMUM Buckling Stress is OK Buckling Stress is OK Critical Load is OK
Therefore the practical Safety Factor achieved =
The Pipe selected is Signal Box
"OPTIMALITY"
Unit Weight of the Pipe
*****CLICK HERE TO SELECT THE PIPE****** [The Standard pipe (API 5L) selected shall be atleast with this cross section area and wall thickness is
minimum (i.e, maximum OD)]
**** CLICK **** TO INCREASE THE
SECTION BY SELECTING NEXT
Dubai Technical dept.
Allowable Stress in slender buckling sallow(sb) = (p 2
* E) / [1.92 * (L/r)2]
sallow(sb) = 136.04 MPa
Euler's Critical Bucling load = (p2
* E * I) / (L)2
Pcr = 1654.06 kN
ncr = 3.24 Nr.
[1]
Length L1 = mm Height h1 = mm
Radius of the bracket R1 = mm Height h2 = mm
Radius of the reinforcement R2 = mm Thickness (Bkt & RF) t = mm
Dia of the hole for Shackle d = mm Weld joints' efficiency hj = %
Dia of the Shackle ring ds = mm Weld Fillet Size sw = mm
Yield stress of the material syield = MPa Elastic Modulus of the material MPa
Allowable Tensile Stress sallow = MPa
637.9 kN 3 * (t = 15 ) mm R2 = 110 mm d = 70 mm R1 = 125 mm h2 = 100 mm b = 60.0 Degrees h1 = 150 mm 318.9 Tensile Force, P = Comp.Force, C=
(a-v) Shearing stress in the shackle ring OK OPTIMUM
(b) Weld (set-on double fillet) size for eye-bracket with the beam OK OPTIMUM
248 155
210000
Design Criterion Signal Box "SAFE DESIGN" Signal Box "OPTIMALITY"
! Initially "assume" then "Iterate" these values with the help of following Signal Boxes
15 Calculations for the Slender Range, Pls. ignore for the Intermediate-block
OK Check for the Ultimate Buckling load Pu, which is the Euler's Critical load Pcr
OK
110
150 100 400
This section is computed in accordance to the Manual Of Steel Construction , 9th edition, American Institute of Steel Construction, New Yark, 1959
125
('C) DESIGN OF ATTACHMENTS - (a) Design of eye bracket for strength
OPTIMUM
Euler's Critical Buckling Load Buckling safety margin
OPTIMUM
=
10
90 70
OPTIMUM
(a-iv) Out-of plane buckling of the eye-bracket OK OPTIMUM
OK
(a-i) Tensile stress in the eye-bracket OPTIMUM
OPTIMUM
(a-ii) Bearing / Crushing stress in the eye-bracket OK
76
(a-iii) Tearing stress in the eye-bracket
OK
Actual Compressive Force on Beam X Safety Factor in Compression
Dubai Technical dept.
ds = 76 mm
~ 2R1= 250 mm
3 * (t = 15 ) mm
Resisting area for tension of the eye braket = Diameteral Difference X Total Thickness =
Resisting Area At = 7830 mm
2
Normal Force P = 637.9 kN
Tensile Stress = Normal Force / Resisting Area
st = 81.5 MPa
Factor of safety with yield stress n1 = 3.0 Nr.
ds = 76 mm
3 * (t = 15 ) mm
Bearing area of the Sling hole for the Sling ring = Diameter of the Sling ring X Total Thickness = ds * 3(t)
Bearing Area Ab = 3420 mm
2
Normal Force P = 637.9 kN
Bearing Stress = Normal Force / Bearing Area
sbearing = 186.5 MPa
OK (2R1 - ds) * 3t
OPTIMUM (a-ii) Design of eye bracket for bearing/crushing strength - FAILURE MODE -2 (80% of the yield stress is governing)
OK (a-i) Design of eye bracket for tensile strength - FAILURE MODE - 1 (allowable tensile stress is governing)
Dubai Technical dept.
3 * (t = 15 ) mm
The bracket is in tearing due to shear along two planes against the sling ring, i.e., resisting it with the chordal sections
X Thickness X Total Thickness = Tearing area At = 7200 mm 2 Tearing Force P = 637.9 kN
Tearing Stress = Tearing Force / Tearing Area
stearing = 88.6 MPa
Factor of safety with yield stress n3 = 2.8 Nr.
Requirement is the minimum thickness of the eye-bracket shall be ensured for 13 mm and 0.25 times the hole diameter d.
Required thickness = 0.25 * d
treq = 22.5 mm
Factor of safety with thickness provided n4 = 2.0 Nr.
[2]
Chordal (assumed to be Radial) area resisting the tearing shear
(a-iv) Design of eye bracket for out-of plane buckling - FAILURE MODE - 4 (as per David T. Ricker [2])
This section is computed in accordance to David T. Ricker, " Design and Construction of Lifting Beams ", Engineering Journal, 4th Quarter, 1991
OK OPTIMUM Radii Difference
= 2 X +
Radii difference for the bracket
OPTIMUM OK (a-iii) Design of eye bracket for tearing strength - FAILURE MODE - 3 (50% of the yield stress is governing)
Radii difference for the reinfrmnt 2 * [(R1 - d/2) * t] + [(R2 - d/2) * (t*2)]
Dubai Technical dept.
3 * (t = 15 ) mm
The curved shackle ring is under double shear along two parallel planes of the faces of the bracket, i.e., resisting it with the cross section area The cross section area of the curved sling ring =
Shearing area As = 9073 mm
2
Shearing Force P = 637.9 kN
Shearing Stress = Shearing Force / Shearing Area
sshearing = 70.3 MPa
Factor of safety with yield stress n3 = 3.5 Nr.
637.9 kN 3 * (t = 15 ) mm R2 = 110 mm d = 70 mm R1 = 125 mm h2 = 100 mm b = 60.0 Degrees h1 = 150 mm 318.9 L1 = 400 mm OPTIMUM (a-v) Design of shackle ring for shearing strength - FAILURE MODE - 5 (50% of the yield stress is governing)
Tensile Force, P =
(b) Design of weld joint of the eye-bracket with the spreader beam for shear strength (50% of the allowable stress is governing) 2 * [p/4 * ds
2
]
OK
Dubai Technical dept.
A) Shear Stress on the Weld joints between the eye-bracket and the beam (Set-on double fillet without any grooving) Total length of the weld joint parallel to the beam axis = (2+2) * (L1 + R1)
Lw1 = 2100 mm
Transverse load on these joints = W/2
Pw1 = 552.4 kN
Allowable Shear Stress on effective throat area = (sallow / 2) * hj
tallow-w = 52.5 MPa
Effective throat thickness = Pw1 * 1000 / (sw * Lw1)
tw = 5.01 mm
Minimum Fillet Size of the Welds = 2 * tw
sw = 7.09 mm
Factor of safety with fillet size provided n4 = 1.4 Nr. OPTIMUM
Dubai Technical dept.
Date
Project:Job No.
Safe Working Load, SWL kN
Spreading Length, L metres
Length, L1 metres
Initial Assumpn. Cant.lvr. Length, L2 metres
Yield stress of the Beam material MPa
Allowable Stress MPa
Elastic Modulus of the material MPa
UDL, q = 0.1 kN/m SWL, W = 552.9 kN y x x Lgth, L1 = 1.998 metres Lgth, L2 = 0.202 metres 4.000 metres P = 276.2 kN P = 276.2 kN
Ensuring the Translational equillibrium along y axis, We have to equate the downward forces with upward reactions
=> W = (2 * P) + q * (L + L2)
W = 552.90 kN
Ensuring the Rotational equillibrium about z axis, We have to equate the clockwise moments with counter clockwise moments
Taking the moments about the node
(W * L1) + ((q * L2) * L2/2)) = (P * L) + ((q * L) * L/2)
L2 = (2/q) * [(P * L) + ((q * L) * L/2) - (W * L1)]
L2 = 4.312 m
(A) STRENGTH DESIGN - Design for FLEXURAL Bending Stress **** Selecting the Section initially based on this ****
PLS. CHANGE THE INITIAL ASSUMPTION
210000 1.998
prepared by
Venkat
248 0.202 4.000After reaching Flexural Stress "safe", Iterate this dimension L2 sothat this agrees with computed L2
155
Value brought from previous worksheet
Geometry of Lifting at the each end of the HOLLOW PIPE Spreader Beam, Solved using the equations of Static Equillibrium
Spreading Length, L =
Hence, the STRUCTURAL analysis is made for the FLEXURAL Stress
As this Adjustable Spreader beam is constrained for all its three planar DOF (x,y & Rz Degrees Of Freedom) at the nodes of application of load,
The bar behaves like a FRAME member and it will resist BOTH the AXIAL force and BENDING in the x-y plane.
This Spreader Beam is a typical case of Both the ends fixed with a Cantilever for Counter-weight, having a point load at an offset and UDL for the entire length. The governing stress for such a configuration is the FLEXURAL STRESS (sb).
DESIGN OF ADJUSTABLE SPREADER LIFTING BEAM of Standard Profile "HEB Series"
Hitachi Zosen, Arzew Plant, Algeria "BLOCK-E" 4776 552.4
12/5/2013
Belleli Energy srl, Dubai Branch
A
D
B
C
C
Dubai Technical dept.
Bending Moment = (P * L) + ((q * L) * L/2)
M = 1105.760 kN-m
= M / Zx
sf(max) = 21264.6 MPa
Factor of Safety achieved on yield stress = syield / sf(max)
n1 = 0.01 Nr. as per EN 53-62 12.20 kg/m 2370000 mm4 921000 mm4 38.90 mm 24.30 mm 52000 mm3 18400 mm3 91 mm 100 mm dmax = 1481.222 mm
Depth of the section, h = Width of the section, b = Elastic Section Modulus, Zx=
Elastic Section Modulus, Zy=
(B) STIFFNESS DESIGN - Design for DEFLECTION Structural member section
= W * L1* (L 2 - L1 2 )3/2 Radius of Gyration, rx= Moments of Inertia, Ixx=
Unit Weight of the member
Bending Stress is OPTIMUM
9 * 31/2 * L * E * I The maximum deflection of the beam between
loaded nodes and
Radius of Gyration, ry=
Signal Block "SAFE DESIGN" Flexural Stress is NOT OK
Counter Weight is NOT OK
Moments of Inertia, Iyy=
PLS. INCREASE THE SECTION
Max. deflection is NOT OK
Signal Block "OPTIMALITY" We have, Maximum Flexural Stress
OPTIMUM
PLS. INCREASE THE SECTION
HE 100 AA
Section Modulus of the section about the axis perpendicular to plane of bending /
Bending Moment =
*********** CLICK HERE **********
TO SELECT THE SECTION
[The Standard Section (EN 53-62) selected
shall be atleast with this Moment of Inertia]
**** CLICK **** TO INCREASE THE SECTION BY SELECTING NEXT SECTION
C
B
Dubai Technical dept.
Length of the bracket Lb = mm Radius of the lug end R= mm
Clearance above the beam c= mm Diameter of the hole dh = mm
Total Height of the lug h1 = mm Diameter of the pin dp = mm
Height of the cut in the lug h2 = mm Thickness of the lug t1 = mm
Height of taper in the lug h3 = mm Thk of all other plates t2 = mm
Total Width of the lug w1 = mm Weld joints' efficiency hj = %
Width of the cut in the lug w2 = mm Weld Fillet Size sw = mm
Yield stress (all matl ex. pin) syield = MPa Elastic Modulus of the material MPa
Allowable Stress sallow = MPa Yield stress (pin matl) sy(pin) = MPa
W = 552.9 kN w1 = 350 R = 120 t1 = 30 dp = 50 w2 = 120 dh = 60 h3 = 145 h2 = 50 h1 = 300 (h + c) = 131 = = Lb = 200 t2 = 10 b = 100
The load on the bracket is the straight forward lifting force acting vertically upwards against the load.
300
(c) Tensile stress in the end plate OK OPTIMUM
(d) Weld (set-on double fillet) size for the bottom plate with other plates OK OPTIMUM
(C) DESIGN OF ATTACHMENTS - (a) Design of adjustable (CG location variations) suspension bracket for strength 200 40 50 120 60 50 30 300 145 350 120 10 70 10
! Initially "assume" then "Iterate" these values with the help of following Signal Boxes
Design Criterion Signal Box "SAFE DESIGN" Signal Box "OPTIMALITY"
248 210000
155
(a-i) Tensile stress in the lug OK NOT OPTIMUM
(a-ii) Bearing / Crushing stress in the lug OK OPTIMUM
(a-iii) Tearing stress in the lug OK OPTIMUM
(a-iv) Out-of plane buckling of the lug OK OPTIMUM
(a-v) Shearing stress in the pin OK OPTIMUM
Dubai Technical dept. wcs = 309 W = 552.9 kN R = 120 t1 = 30 dh = 60 t1 = 30 h3 = 145 h1 = 300 w1 = 350 h2 = 50 h3 - R
tan sin-1 + tan-1
(w1 / 2)
wcs = 309mm
= Width at the critical section - Diameter of the hole = wcs - dh
wef = 249mm
= wef * t1
Aef = 7480mm
2
As these two lugs are placed, with the lifting lug in-between, at a closer clearance always, the bending effects on the lug and the pin are ignored. And also, it could be reasonably assumed that the entire force of lifting is shared equally without any moments on them.
The tensile stress on this critical section = Force on the lug / Effective normal area
= (W/2) / Aef
= Effective width
The effective width at the critical section
X Thickness
The effective normal area at the critical section resisting the force per lug
(a-i) Design of lugs on the bracket for tensile strength - FAILURE MODE - 1 (allowable tensile stress is governing)
h3 - R R (h3 - R) 2 + (w 1 / 2) 2 The width of the critical section i.e., across the
Dubai Technical dept.
W = 552.9 kN
wb = 50 t1 = 30
t1 = 30 dp = 50
The effective area bearing the crushing force per lug = Bearing width X Thickness
= wb * t1 ( Note: Bearing width equals the projected diameter
Ab = 1500mm
2
The bearing / crushing stress = Crushing force / Bearing area
= (W/2) / Ab
sb = 184.30MPa
Factor of Safety achieved on yield stress = syield / sb
n3 = 1.35 Nr.
W = 552.9 kN
t1 = 30
t1 = 30
(R - dh/2)= 90
Area resisting lateral tension (tearing) per lug = Radii difference X Thickness
= (R - dh/2) * t1
OK
OPTIMUM
(a-iii) Design of lug on the bracket for tearing strength - FAILURE MODE - 3 (50% of the yield stress is governing) (a-ii) Design of lugs on the bracket for bearing/crushing strength - FAILURE MODE -2 (80% of the yield stress is governing)
Dubai Technical dept.
Tearing stress = Tearing force / Area resisting lateral tension (tearing)
= (W/2) / At ( Note: Tearing force conservatively equals lifiting force stear = 102.39MPa
Factor of Safety achieved on yield stress = syield / sbtear
n4 = 2.42 Nr.
Requirement is the minimum thickness of the lug on the bracket shall be ensured for 13 mm and 0.25 times the hole diameter d.
Required thickness = 0.25 * dh
treq = 15.0 mm
Factor of safety with thickness provided n5 = 2.0 Nr.
[1]
W = 552.9 kN
t1 = 30
dp = 50
The pin under double shear along two parallel planes of the inner faces of the lugs, i.e., resisting it with the cross section area
The cross section area of the pin = 2 * [p/4 * dp
2
]
Shearing area As = 3927 mm
2
(a-v) Design of pin for shearing strength - FAILURE MODE - 5 (50% of the yield stress of the pin is governing) (a-iv) Design of lug on the bracket for out-of plane buckling - FAILURE MODE - 4 (as per David T. Ricker [1])
OK
This section is computed in accordance to David T. Ricker, " Design and Construction of Lifting Beams ", Engineering Journal, 4th Quarter, 1991
OK
OPTIMUM
Dubai Technical dept. W = 552.9 kN w1 = 350 t1 = 30 w2 = 120 h3 = 145 h4 = 116 h1 = 300 h2 = 50 t2 = 10 b = 100
Fixing the height h4 at 75% of the straight height (h1 - h3)
h4 = 116 mm
Total weld-length provided per lug = 2 * [2 * (h2 + h4 + t2 + h4) + b]
Lw1 = 1370 mm
Transverse force on the weld joint per lug = W/2
Pw1 = 276.5 kN
Allowable Shear Stress on effective throat area = (sallow / 2) * hj
tallow-w = 54.25 MPa
Effective throat thickness = Pw1 * 1000 / (sw * Lw1)
tw1 = 3.72 mm
Minimum Fillet Size of the Welds = 2 * tw
Dubai Technical dept.
W = 552.9 kN
= =
Lb = 200
t2 = 10
The load on the end plates of the bracket is the straight forward lifting force acting vertically against the load. The normal area per end plate resisting tensile force = Length of the bracket X Thickness
= Lb * t2
Aep = 2000 mm
2
As these two end plates are fabricated as box and the thickness is sufficiently large, the membrane effects and bending effects are ignored. And also, it could be reasonably assumed that the entire force of lifting is shared equally without any moments on them.
The tensile stress on the cross section = Force on the end plate / Normal area
= (W/2) / Aef
st(ep) = 138.23MPa
Factor of Safety achieved on yield stress = syield / st(ep)
n8 = 1.79 Nr.
(c) Design of end plates of the adjustable bracket for tensile strength (allowable tensile stress is governing)
OK
Dubai Technical dept. W = 552.9 kN h5 = 67 = = Lb = 200 b = 100
Fixing the height h5 at one-third of length of the bracket, Lb
h5 = 67 mm
Total weld-length provided = Directly for bottom plate X Indirectly for ribs supporitng bottom plate
Total weld-length provided = 2 * (Lb + b) + 4 *4* h5
Lw2 = 1567 mm
Transverse force on the weld joint = W
Pw2 = 552.9 kN
Allowable Shear Stress on effective throat area = (sallow / 2) * hj
tallow-w = 54.25 MPa
Effective throat thickness = Pw1 * 1000 / (sw * Lw1)
tw2 = 6.51 mm
Minimum Fillet Size of the Welds = 2 * tw
sw2 = 9.20 mm
Factor of safety with fillet size provided n9 = 1.1 Nr.
OK OPTIMUM
Dubai Technical dept.
Length of the bracket Lb = mm Radius of the lug end R= mm
Clearance above the beam c= mm Diameter of the hole dh = mm
Total Height of the lug h1 = mm Diameter of the pin dp = mm
Height of the cut in the lug h2 = mm Thickness of the lug t1 = mm
Height of taper in the lug h3 = mm Thk of all other plates t2 = mm
Total Width of the lug w1 = mm Weld joints' efficiency hj = %
Width of the cut in the lug w2 = mm Weld Fillet Size sw = mm
Yield stress (all matl ex. pin) syield = MPa Elastic Modulus of the material MPa
Allowable Stress sallow = MPa Yield stress (pin matl) sy(pin) = MPa
t2 = 8 b = 100 Lb = 150 = = h2 = 50 (h + c) = 111 h1 = 200 h3 = 150 dh = 60 w2 = 116 dp = 48 w1 = 350
(D) DESIGN OF ATTACHMENTS - (a) Design of adjustable (Span variations) suspension bracket for strength
200 48 50 15 150 120 20 60 116 8 248 210000 150 8 350 70 155 300
! Initially "assume" then "Iterate" these values with the help of following Signal Boxes
Design Criterion Signal Box "SAFE DESIGN" Signal Box "OPTIMALITY"
(a-i) Tensile stress in the lug OK NOT OPTIMUM
(a-ii) Bearing / Crushing stress in the lug OK OPTIMUM
(a-iii) Tearing stress in the lug OK OPTIMUM
(a-iv) Out-of plane buckling of the lug OK OPTIMUM
(a-v) Shearing stress in the pin OK OPTIMUM
(b) Weld (set-on double fillet) size for lug with other plates OK OPTIMUM
(c) Tensile stress in the end plate OK OPTIMUM
Dubai Technical dept. w1 = 350 h2 = 50 h1 = 200 h3 = 150 dh = 60 t1 = 15 R = 120 t1 = 15 wcs = 304 W = 276.2 kN h3 - R
tan sin-1 + tan-1
(w1 / 2)
wcs = 304mm
= Width at the critical section - Diameter of the hole = wcs - dh
wef = 244mm
= wef * t1
Aef = 3653mm
2
As these two lugs are placed, with the lifting lug in-between, at a closer clearance always, the bending effects on the lug and the pin are ignored. And also, it could be reasonably assumed that the entire force of lifting is shared equally without any moments on them.
The tensile stress on this critical section = Force on the lug / Effective normal area
= (W/2) / Aef
st = 37.80MPa
Factor of Safety achieved on yield stress = syield / st
n2 = 6.56 Nr.
OK
NOT OPTIMUM
The effective width at the critical section
The effective normal area at the critical section
resisting the force per lug = Effective width X Thickness
(a-i) Design of lugs on the bracket for tensile strength - FAILURE MODE - 1 (allowable tensile stress is governing)
The width of the critical section i.e., across the
diameter of the hole = w1 - 2 *
h3 - R R (h3 - R) 2 + (w1 / 2) 2
Dubai Technical dept.
dp = 48
t1 = 15
t1 = 15
wb = 48 W = 276.2 kN
The effective area bearing the crushing force per lug = Bearing width X Thickness
= wb * t1 ( Note: Bearing width equals the projected diameter
Ab = 720mm
2
The bearing / crushing stress = Crushing force / Bearing area
= (W/2) / Ab
sb = 191.81MPa
Factor of Safety achieved on yield stress = syield / sb
n3 = 1.29 Nr.
(R - dh/2) = 90
t1 = 15
(a-ii) Design of lugs on the bracket for bearing/crushing strength - FAILURE MODE -2 (80% of the yield stress is governing)
OK
OPTIMUM
Dubai Technical dept.
Tearing stress = Tearing force / Area resisting lateral tension (tearing)
= (W/2) / At ( Note: Tearing force conservatively equals lifiting force stear = 102.30MPa
Factor of Safety achieved on yield stress = syield / sbtear
n4 = 2.42 Nr.
Requirement is the minimum thickness of the lug on the bracket shall be ensured for 13 mm and 0.25 times the hole diameter d.
Required thickness = 0.25 * dh
treq = 15.0 mm
Factor of safety with thickness provided n5 = 1.0 Nr.
[1]
dp = 48
t1 = 15
W = 276.2 kN The pin under double shear along two parallel planes of the inner faces of the lugs, i.e., resisting it with the cross section area
The cross section area of the pin = 2 * [p/4 * dp
2
]
Shearing area As = 3619 mm
2
Shearing Force P = 276.2 kN
Shearing Stress = Shearing Force / Shearing Area
sshearing = 76.3 MPa
Factor of safety with yield stress n6 = 3.9 Nr.
This section is computed in accordance to David T. Ricker, " Design and Construction of Lifting Beams ", Engineering Journal, 4th Quarter, 1991
(a-v) Design of pin for shearing strength - FAILURE MODE - 5 (50% of the yield stress of the pin is governing)
OK OPTIMUM
OK
OPTIMUM
(a-iv) Design of lug on the bracket for out-of plane buckling - FAILURE MODE - 4 (as per David T. Ricker [1])
OK OPTIMUM
Dubai Technical dept. t2 = 8 b = 100 h2 = 50 h4 = 38 h1 = 200 h3 = 150 w2 = 116 w1 = 350 t1 = 15 W = 276.2 kN Fixing the height h4 at 75% of the straight height (h1 - h3)
h4 = 38 mm
Total weld-length provided per lug = 2 * [2 * (h2 + h4 + t2 + h4) + b]
Lw1 = 732 mm
Transverse force on the weld joint per lug = W/2
Pw1 = 138.1 kN
Allowable Shear Stress on effective throat area = (sallow / 2) * hj
Dubai Technical dept.
t2 = 8
Lb = 150
= =
W = 276.2 kN The load on the end plates of the bracket is the straight forward lifting force acting vertically against the load. The normal area per end plate resisting tensile force = Length of the bracket X Thickness
= Lb * t2
Aep = 1200 mm
2
As these two end plates are fabricated as box and the thickness is sufficiently large, the membrane effects and bending effects are ignored. And also, it could be reasonably assumed that the entire force of lifting is shared equally without any moments on them.
The tensile stress on the cross section = Force on the end plate / Normal area
= (W/2) / Aef
st(ep) = 115.08MPa
Factor of Safety achieved on yield stress = syield / st(ep)
n8 = 2.15 Nr.
(c) Design of end plates of the adjustable bracket for tensile strength (allowable tensile stress is governing)
OK
Dubai Technical dept. b = 100 Lb = 150 = = h5 = 50 W = 276.2 kN Fixing the height h5 at one-third of length of the bracket, Lb
h5 = 50 mm
Total weld-length provided = Directly for bottom plate X Indirectly for ribs supporitng bottom plate
Total weld-length provided = 2 * (Lb + b) + 2*4 * h5]
Lw2 = 800 mm
Transverse force on the weld joint = W
Pw2 = 276.2 kN
Allowable Shear Stress on effective throat area = (sallow / 2) * hj
tallow-w = 54.25 MPa
Effective throat thickness = Pw1 * 1000 / (sw * Lw1)
tw2 = 6.36 mm