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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Single Span » Wide Flange Steel I Beam » W8 × 21
Wide Flange Steel I Beam | Single Span | Two Equal Spans | Three Equal Spans | Four Equal Spans

For a simply supported beam in a single span, the maximum displacement w_max and the maximum normal stress stress_max occur at the center of the beam.
The tabulated data listed in this page are calculated based on the area moment of inertia (Ixx = 75.3 in4) for the W8 × 21 Wide Flange Steel I Beam and the typical Young's modulus (E = 3.046 × 107 psi) of steels. Note that the typical yielding stress Yield of steels can range from 1.015 × 104 to 2.970 × 105 psi. The purpose of this page is to give a rough estimation of the load-bearing capacity of this particular beam, rather than a guideline for designing actual building structures. Please check your local building codes for regulatory requirements.
Note: The weight of the beam itself is not included in the calculation.
L = 3 ft
L = 5 ft
L = 10 ft
L = 15 ft
L = 20 ft
L = 25 ft
L = 30 ft
L = 40 ft
L = 50 ft
L = 60 ft
L = 70 ft
   
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 1.67 × 10-5 15.6
30.0 2.38 × 10-5 22.3
40.0 3.18 × 10-5 29.7
50.0 3.97 × 10-5 37.1
60.0 4.77 × 10-5 44.5
70.0 5.56 × 10-5 52.0
80.0 6.36 × 10-5 59.4
90.0 7.15 × 10-5 66.8
100 7.95 × 10-5 74.2
200 1.59 × 10-4 148
300 2.38 × 10-4 223
400 3.18 × 10-4 297
500 3.97 × 10-4 371
600 4.77 × 10-4 445
700 5.56 × 10-4 520
800 6.36 × 10-4 594
900 7.15 × 10-4 668
1000 7.95 × 10-4 742
2000 0.00159 1480
3000 0.00238 2230
4000 0.00318 2970
5000 0.00397 3710
6000 0.00477 4450
7000 0.00556 5200
8000 0.00636 5940
9000 0.00715 6680
1.00 × 104 0.00795 7420
2.00 × 104 0.0159 1.48 × 104
3.00 × 104 0.0238 2.23 × 104
4.00 × 104 0.0318 2.97 × 104
5.00 × 104 0.0397 3.71 × 104
6.00 × 104 0.0477 4.45 × 104
7.00 × 104 0.0556 5.20 × 104
8.00 × 104 0.0636 5.94 × 104
9.00 × 104 0.0715 6.68 × 104
1.00 × 105 0.0795 7.42 × 104
2.00 × 105 0.159 1.48 × 105
3.00 × 105 0.238 2.23 × 105
4.00 × 105 0.318 2.97 × 105
4.00 × 105 0.318 2.97 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 1.29 × 10-4 43.3
30.0 1.84 × 10-4 61.9
40.0 2.45 × 10-4 82.5
50.0 3.07 × 10-4 103
60.0 3.68 × 10-4 124
70.0 4.29 × 10-4 144
80.0 4.91 × 10-4 165
90.0 5.52 × 10-4 186
100 6.13 × 10-4 206
200 0.00123 412
300 0.00184 619
400 0.00245 825
500 0.00307 1030
600 0.00368 1240
700 0.00429 1440
800 0.00491 1650
900 0.00552 1860
1000 0.00613 2060
2000 0.0123 4120
3000 0.0184 6190
4000 0.0245 8250
5000 0.0307 1.03 × 104
6000 0.0368 1.24 × 104
7000 0.0429 1.44 × 104
8000 0.0491 1.65 × 104
9000 0.0552 1.86 × 104
1.00 × 104 0.0613 2.06 × 104
2.00 × 104 0.123 4.12 × 104
3.00 × 104 0.184 6.19 × 104
4.00 × 104 0.245 8.25 × 104
5.00 × 104 0.307 1.03 × 105
6.00 × 104 0.368 1.24 × 105
7.00 × 104 0.429 1.44 × 105
8.00 × 104 0.491 1.65 × 105
9.00 × 104 0.552 1.86 × 105
1.00 × 105 0.613 2.06 × 105
1.44 × 105 0.883 2.97 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.00206 173
30.0 0.00294 247
40.0 0.00392 330
50.0 0.00491 412
60.0 0.00589 495
70.0 0.00687 577
80.0 0.00785 660
90.0 0.00883 742
100 0.00981 825
200 0.0196 1650
300 0.0294 2470
400 0.0392 3300
500 0.0491 4120
600 0.0589 4950
700 0.0687 5770
800 0.0785 6600
900 0.0883 7420
1000 0.0981 8250
2000 0.196 1.65 × 104
3000 0.294 2.47 × 104
4000 0.392 3.30 × 104
5000 0.491 4.12 × 104
6000 0.589 4.95 × 104
7000 0.687 5.77 × 104
8000 0.785 6.60 × 104
9000 0.883 7.42 × 104
1.00 × 104 0.981 8.25 × 104
2.00 × 104 1.96 1.65 × 105
3.00 × 104 2.94 2.47 × 105
3.60 × 104 3.53 2.97 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.0104 390
30.0 0.0149 557
40.0 0.0199 742
50.0 0.0248 928
60.0 0.0298 1110
70.0 0.0348 1300
80.0 0.0397 1480
90.0 0.0447 1670
100 0.0497 1860
200 0.0993 3710
300 0.149 5570
400 0.199 7420
500 0.248 9280
600 0.298 1.11 × 104
700 0.348 1.30 × 104
800 0.397 1.48 × 104
900 0.447 1.67 × 104
1000 0.497 1.86 × 104
2000 0.993 3.71 × 104
3000 1.49 5.57 × 104
4000 1.99 7.42 × 104
5000 2.48 9.28 × 104
6000 2.98 1.11 × 105
7000 3.48 1.30 × 105
8000 3.97 1.48 × 105
9000 4.47 1.67 × 105
1.00 × 104 4.97 1.86 × 105
1.60 × 104 7.95 2.97 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.0330 693
30.0 0.0471 990
40.0 0.0628 1320
50.0 0.0785 1650
60.0 0.0942 1980
70.0 0.110 2310
80.0 0.126 2640
90.0 0.141 2970
100 0.157 3300
200 0.314 6600
300 0.471 9900
400 0.628 1.32 × 104
500 0.785 1.65 × 104
600 0.942 1.98 × 104
700 1.10 2.31 × 104
800 1.26 2.64 × 104
900 1.41 2.97 × 104
1000 1.57 3.30 × 104
2000 3.14 6.60 × 104
3000 4.71 9.90 × 104
4000 6.28 1.32 × 105
5000 7.85 1.65 × 105
5280 8.28 1.74 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.0805 1080
30.0 0.115 1550
40.0 0.153 2060
50.0 0.192 2580
60.0 0.230 3090
70.0 0.268 3610
80.0 0.307 4120
90.0 0.345 4640
100 0.383 5150
200 0.766 1.03 × 104
300 1.15 1.55 × 104
400 1.53 2.06 × 104
500 1.92 2.58 × 104
600 2.30 3.09 × 104
700 2.68 3.61 × 104
800 3.07 4.12 × 104
900 3.45 4.64 × 104
1000 3.83 5.15 × 104
2000 7.66 1.03 × 105
2160 8.28 1.11 × 105
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.167 1560
30.0 0.238 2230
40.0 0.318 2970
50.0 0.397 3710
60.0 0.477 4450
70.0 0.556 5200
80.0 0.636 5940
90.0 0.715 6680
100 0.795 7420
200 1.59 1.48 × 104
300 2.38 2.23 × 104
400 3.18 2.97 × 104
500 3.97 3.71 × 104
600 4.77 4.45 × 104
700 5.56 5.20 × 104
800 6.36 5.94 × 104
900 7.15 6.68 × 104
1000 7.95 7.42 × 104
1040 8.28 7.73 × 104
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 0.527 2770
30.0 0.753 3960
40.0 1.00 5280
50.0 1.26 6600
60.0 1.51 7920
70.0 1.76 9240
80.0 2.01 1.06 × 104
90.0 2.26 1.19 × 104
100 2.51 1.32 × 104
200 5.02 2.64 × 104
300 7.53 3.96 × 104
330 8.28 4.35 × 104
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 1.29 4330
30.0 1.84 6190
40.0 2.45 8250
50.0 3.07 1.03 × 104
60.0 3.68 1.24 × 104
70.0 4.29 1.44 × 104
80.0 4.91 1.65 × 104
90.0 5.52 1.86 × 104
100 6.13 2.06 × 104
135 8.28 2.78 × 104
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 2.67 6230
30.0 3.81 8910
40.0 5.09 1.19 × 104
50.0 6.36 1.48 × 104
60.0 7.63 1.78 × 104
65.1 8.28 1.93 × 104
Steel I Beam: W8 × 21 (Wide Flange 8 inch tall × 21 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
21.0 4.95 8490
30.0 7.07 1.21 × 104
35.2 8.28 1.42 × 104
Additional Information
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STEM Career Outlook

Wages, employment opportunities, and growth projections for STEM jobs.

CNC Machining Design Guide

Optimize your designs, reduce machining time, and lower your costs.

Essentials of Manufacturing

Information, coverage of important developments and expert commentary in manufacturing.

Injection Molding Design Guide

Guide for high quality and cost-effective plastic injection molding.

more publications