Smit Bracket Design Calculator

Based on AISC ASD 9th Edition & API RP 2A WSD 2010 Standards

Developed by Hrithin

Input Parameters

Allowable Stresses

Pinhole Checks

Base Plate Checks

Weld Checks

Material Properties

Material yield stress, sy (MPa)

Weld electrode tensile strength, sU (MPa)

Modulus of elasticity, E (MPa)

Poisson's ratio, v

Smit Bracket Geometry

Radius of main plate, R (mm)

Thickness of main plate, t (mm)

Diameter of eye pin hole, De (mm)

Diameter of cheek plate, DC (mm)

Thickness of cheek plate, tC (mm)

Total height of smit bracket, H (mm)

Length of base plate, L (mm)

Base weld leg size, tW (mm)

Cheek plate weld size, tWC (mm)

Pin length, Lpin (mm)

Pin diameter, DP (mm)

Smit Bracket Load

Load on smit bracket, PS (MT)

Angle of load with vertical, θ (deg)

Out of plane angle, φ (deg)

Dynamic load factor, DLF

Smit Bracket Diagram

Smit Bracket Schematic

Design Summary

Load Distribution

Total load (PS): 80 MT

Load per side (P): 40 MT

Design load (Pd): 100 MT

Vertical load (PZ): 0 MT

Horizontal load (Py): 39.85 MT

Lateral load (Px): 3.49 MT

Critical Stresses

Max bearing stress: 154.7 MPa

Max shear stress: 69.0 MPa

Max tensile stress: 81.2 MPa

Max Von Mises: 199.8 MPa

Base weld stress: 156.8 MPa

Cheek weld stress: 82.3 MPa

Design Review Required

Some stress checks exceed allowable limits

Pinhole OK Base FAIL Weld OK

Allowable Stresses Calculation

Material yield stress, sy = 235 MPa

Base value for all calculations

Weld electrode tensile strength, sU = 480 MPa

For weld stress calculations only

Stress Factors

Stress Type	Factor	Formula
Bearing stress	0.90	0.9 × sy
Bending (In-plane)	0.60	0.6 × sy
Bending (Out of plane)	0.75	0.75 × sy
Tensile stress	0.60	0.6 × sy
Tensile at pinhole	0.45	0.45 × sy
Shear stress	0.40	0.4 × sy
Von Mises stress	0.75	0.75 × sy
Hertz stress	2.50	2.5 × sy
Weld stress	0.30	0.3 × sU

Calculated Allowable Stresses

Parameter	Value	Unit
Allowable bearing stress, sbe(allow)	211.5	MPa
Allowable bending stress (In-plane), sbd(allow)	141.0	MPa
Allowable bending stress (Out of plane), sbdo(allow)	176.3	MPa
Allowable tensile stress, st(allow)	141.0	MPa
Allowable tensile stress at pinhole, stp(allow)	105.8	MPa
Allowable shear stress, tS(allow)	94.0	MPa
Allowable Von Mises stress, sV(allow)	176.3	MPa
Allowable Hertz stress, sH(allow)	587.5	MPa
Allowable weld stress, sW(allow)	144.0	MPa

Allowable Stresses Summary

All allowable stresses are calculated based on material yield strength and applicable safety factors as per AISC ASD standards.

Pinhole Geometry & Loads

Design bearing load, Pd = 100 MT

Total design load on pinhole

Pin diameter, DP = 135 mm

Diameter of the pin

Main plate thickness, t = 36 mm

Thickness of main plate

Cheek plate thickness, tC = 28 mm

Thickness of cheek plate

Pin hole diameter, De = 140 mm

Diameter of pin hole in eye

Radius of main plate, R = 170 mm

Radius from center to edge

Radius of cheek plate, RC = 140 mm

Half of cheek plate diameter

Calculated Areas

Area Type	Value	Unit	Formula
Bearing area, Abe	7068.6	mm²	π/4 × DP × (t + tC)
Shear area, ASD	15480.0	mm²	2 × [(R - De/2)×t + (RC - De/2)×tC]
Tensile area A-A, At1p	15480.0	mm²	2 × [(R - De/2)×t + (RC - De/2)×tC]
Tensile area B-B, At2p	33264.0	mm²	(2R + π×RC/2) × t
Pin section area, Apin	14313.7	mm²	π/4 × DP²

Pinhole Stress Checks

Bearing Stress Check

Parameter	Value	Unit	Status
Bearing stress, sbe	154.7	MPa	OK
Allowable bearing stress	211.5	MPa

Shear Stress Check

Parameter	Value	Unit	Status
Shear stress at pinhole, ssp	63.4	MPa	OK
Allowable shear stress	94.0	MPa

Tensile Stress Check

Parameter	Value	Unit	Status
Tensile stress A-A, stp	81.2	MPa	OK
Tensile stress B-B, stp	37.8	MPa	OK
Allowable tensile stress	105.8	MPa

Hertz Contact Stress Check

Parameter	Value	Unit	Status
Hertz stress at pin hole, sH	314.5	MPa	OK
Allowable Hertz stress	587.5	MPa

Pin Shear Stress Check

Parameter	Value	Unit	Status
Shear stress at pin, tspin	69.0	MPa	OK
Allowable shear stress	94.0	MPa

Pinhole Stress Checks

Checking pinhole stress values...

Base Plate Geometry & Loads

Base length, L = 760 mm

Length of base plate

Base thickness, t = 36 mm

Thickness of base plate

Moment lever (horizontal), h = 235 mm

H - R = 405 - 170

Moment lever (vertical), e = 210 mm

L/2 - R = 380 - 170

Design Loads at Base

Load Type	Value	Unit
Design tensile force, Pt	0	MT
Design horizontal load, Pyd	49.81	MT
Design vertical load, Pzd	0	MT
Design lateral load, Pxd	4.37	MT

Calculated Properties

Property	Value	Unit	Formula
Tensile area, Atb	27360	mm²	L × t
Shear area, Asb	27360	mm²	L × t
Section modulus (x-axis), Zbxx	3.46E6	mm³	t × L² / 6
Section modulus (y-axis), Zbyy	164160	mm³	L × t² / 6

Base Plate Stress Checks

Tensile Stress Check

Parameter	Value	Unit	Status
Tensile stress at base, stb	0.0	MPa	OK
Allowable tensile stress	141.0	MPa

Bending Stress Check

Parameter	Value	Unit	Status
Bending stress (x-axis), sbbx	119.3	MPa	OK
Allowable bending (in-plane)	141.0	MPa
Bending stress (y-axis), sbby	80.6	MPa	OK
Allowable bending (out of plane)	176.3	MPa

Shear Stress Check

Parameter	Value	Unit	Status
Shear stress (y direction), tsby	17.0	MPa	OK
Shear stress (x direction), tsbx	1.5	MPa	OK
Allowable shear stress	94.0	MPa

Combined Stress Checks

Parameter	Value	Unit/Limit	Status
Von Mises stress, svb	199.8	MPa	FAIL
Allowable Von Mises	176.3	MPa
Combined stress ratio	1.42	(≤ 1.0)	FAIL
AISC H2-1 check	fa/st(allow) + fbx/sbd(allow) + fby/sbdo(allow)		FAIL

Base Plate Checks

Checking base plate stress values...

Weld Geometry

Base weld leg size, tw = 10 mm

Leg size of base weld

Cheek weld leg size, twc = 10 mm

Leg size of cheek plate weld

Base length, d = 760 mm

Length of base weld

Base width, b = 36 mm

Width of base weld

Cheek plate diameter, Dc = 280 mm

Diameter of cheek plate

Calculated Weld Properties

Property	Value	Unit	Formula
Base weld throat, twt	7.07	mm	tw / √2
Total base weld length, Lw	1592	mm	2 × (d + b)
Base weld area, Asbw	11257.1	mm²	twt × Lw
Base weld modulus (x-axis), Zwbxx	1.94E6	mm³	(b×d + d²/3) × tw
Base weld modulus (y-axis), Zwbyy	2.76E5	mm³	(b×d + b²/3) × tw
Cheek weld throat, twtc	7.07	mm	twc / √2
Cheek weld length, Lwc	439.8	mm	π × Dc / 2
Cheek weld area, Awc	3110.2	mm²	twtc × Lwc

Weld Stress Checks

Base Weld Check

Parameter	Value	Unit	Status
Shear stress (y direction), tsbwy	43.4	MPa
Shear stress (x direction), tsbwx	3.8	MPa
Tensile stress, stbw	0.0	MPa
Bending stress (x-axis), sbbwx	214.6	MPa
Bending stress (y-axis), sbbwy	155.0	MPa
Total stress, scbw	156.8	MPa	FAIL
Allowable weld stress	144.0	MPa

Cheek Plate Weld Check

Parameter	Value	Unit	Status
Design load on cheek plate, Pdc	43.75	MT
Weld stress at cheek weld, swc	82.3	MPa	OK
Allowable weld stress	144.0	MPa

Weld Checks

Checking weld stress values...

Design Recommendations

Increase base weld leg size from 10mm to 12mm or more
Consider increasing base plate thickness to reduce bending stresses
Review load distribution or add additional support
Verify material properties and safety factors