Steel Beam Design As Per AISC ASD [PDF]

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AISC Section Properties

Steel Beam Design as per AISC ASD - 89 Beam d bf tf tw

W8x24 7.930 6.500 0.400 0.245

Sx

20.900

Inch Inch Inch Inch Inch3

Sy

5.630

Inch3

Ix

82.700

Inch4

Iy rt

18.300 1.760

Ax rx ry

7.080 3.420 1.610

Inch4 Inch Inch2 Inch Inch

Material Properties Modulus of Elasticity of steel Yeild Stress Ultimate tensile strength Span Data

E Fy Fu

29000.000 36.000 58.000

Ksi Ksi Ksi

Unsupported Span

Lb

10.000

Ft

Length for slenderness

10.000

Ft

Length for slenderness

Lx Lz

10.000

Ft

Loading Data from Staad Applied Moment about X - Axis Applied Moment about Y - Axis Axial Load

Mx (Mz in staad) My fx

46.210 0.030 28.700

Kip-Ft Kip-Ft Kips

K Lx/rx Ly/ry

1.000 35.088

Check for Slenderness

74.534

Pass in Slenderness Computed Stresses Bending Stress @ X- Axis

fbx = Mx / Sx

26.532

Ksi

Bending Stress @ Y- Axis

fby = My / Sy fa= Fx/Ax

0.064

Ksi

4.054

Ksi

Limiting Width Thickness Ratio

bf/tf

8.125 < 10.83333 Section is Compact

Critical Unbraced Length

Lc1= 76bf / fy0.5

82.333

Lc2 = 20000 / (( d / Af ) fy ))

182.149

Inch

Lc

82.333 Lb > Lc 68.182

Inch

Axial Stress Calculation Of Allowable Bending Stresses (Fb)

Lc = min( Lc1:Lc2)

Lb/rt

319.374( Cb / fy)0.5 < lb/rt < 714.143( Cb / fy)0.5 319.374( Cb / fy)0.5 < lb/rt > 714.143( Cb / fy)0.5

Eq- 1 Eq-2 Cb

1.000

319.374( Cb / Fy)0.5

53.229

714.143( Cb / Fy)0.5 Lb/rt

119.024 68.182

lb/rt Satifying Eq-1 Fbx =(2/3 - Fy ( lb/rt )2 / 1530000Cb ) )Fy; Allowable Bending Stress @ X- Axis

170x103Cb/(lb/rt)2

20.062

Ksi

For any value of l/rt

Fbx =12000Cb Af / (lb*d)

21.600

Ksi

Selected Allowable Bending Stress @ X-Axis

Fbx =

21.600

Ksi

Max allowable Bending Stress @ Y-Axis

Fby = 0.75 Fy

27.000

Ksi

Min allowable Bending Stress @ Y-Axis

Fby = 0.6 Fy

21.600

Ksi

Calculated allowable Bending Stress @ Y-Axis

Fby = Fy (1.075 - 0.005bf Fy0.5 / 2tf )

29.925

Ksi

Selected allowable Bending Stress @ Y-Axis

Fby =

27.000

Ksi

Calculation Of Allowable Axial Stresses (Fa) Critical Klb/r

74.534 Cc = (2 p E / Fy) 2

0.5

126.150 KL/r is Less than Cc

Fa = Fy ( 1 - 0.5 * ( Lb / r * Cc)2 /(1.667 + 0.375 * Lb / r * Cc - 0.125 * ( Lb / r * Cc Allowable Stress Allowable Axial Stress

)3); (12 p2 E/Fy)0.5 15.956

Fa=

< 0.7Fy

Interaction Checking fa/Fa

0.254

Interaction Checking 1.485 fa/Fa + Cmxfbx/(1-fa/Fex)Fbx + Cmyfby/(1-fa/fey)Fby < 1.0 (Eq H1-1)

(Eq H1-3)

fa/0.6Fy + fbx/Fbx + fby/Fby < 1.0 (Eq H1-2) fa/Fa + fbx/Fbx + fby/Fby < 1.0 (Eq H1-3) For Restrained against rotation

Cmx,y =

0.850 2

2

fex = 12*p *E / ( 23*Lex / rx )

121.392

fey=12*p 2*E / ( 23*Ley / ry2 )

26.902

Interaction Checking

1.337

(Eq H1-1)

Interaction Checking

1.418

(Eq H1-2)

Govering Stress Ratio 1.48

(Eq H1-3)