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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Three Equal Spans » Wide Flange Steel I Beam » W18 × 71
Wide Flange Steel I Beam | Single Span | Two Equal Spans | Three Equal Spans | Four Equal Spans

For a simply supported beam in three equal spans, we compute the displacement at the middle of the first and the third spans, and the maximum normal stress stress_max occuring at the second and third supports of the beam.
The tabulated data listed in this page are calculated based on the area moment of inertia (Ixx = 1170 in4) for the W18 × 71 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
L = 80 ft
L = 90 ft
L = 100 ft
L = 125 ft
L = 150 ft
   
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 1.90 × 10-6 6.05
80.0 2.14 × 10-6 6.82
90.0 2.40 × 10-6 7.67
100 2.67 × 10-6 8.52
200 5.34 × 10-6 17.0
300 8.01 × 10-6 25.6
400 1.07 × 10-5 34.1
500 1.34 × 10-5 42.6
600 1.60 × 10-5 51.1
700 1.87 × 10-5 59.7
800 2.14 × 10-5 68.2
900 2.40 × 10-5 76.7
1000 2.67 × 10-5 85.2
2000 5.34 × 10-5 170
3000 8.01 × 10-5 256
4000 1.07 × 10-4 341
5000 1.34 × 10-4 426
6000 1.60 × 10-4 511
7000 1.87 × 10-4 597
8000 2.14 × 10-4 682
9000 2.40 × 10-4 767
1.00 × 104 2.67 × 10-4 852
2.00 × 104 5.34 × 10-4 1700
3.00 × 104 8.01 × 10-4 2560
4.00 × 104 0.00107 3410
5.00 × 104 0.00134 4260
6.00 × 104 0.00160 5110
7.00 × 104 0.00187 5970
8.00 × 104 0.00214 6820
9.00 × 104 0.00240 7670
1.00 × 105 0.00267 8520
2.00 × 105 0.00534 1.70 × 104
3.00 × 105 0.00801 2.56 × 104
4.00 × 105 0.0107 3.41 × 104
5.00 × 105 0.0134 4.26 × 104
6.00 × 105 0.0160 5.11 × 104
7.00 × 105 0.0187 5.97 × 104
8.00 × 105 0.0214 6.82 × 104
9.00 × 105 0.0240 7.67 × 104
1.00 × 106 0.0267 8.52 × 104
2.00 × 106 0.0534 1.70 × 105
3.00 × 106 0.0801 2.56 × 105
3.48 × 106 0.0931 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 1.46 × 10-5 16.8
80.0 1.65 × 10-5 18.9
90.0 1.85 × 10-5 21.3
100 2.06 × 10-5 23.7
200 4.12 × 10-5 47.4
300 6.18 × 10-5 71.0
400 8.24 × 10-5 94.7
500 1.03 × 10-4 118
600 1.24 × 10-4 142
700 1.44 × 10-4 166
800 1.65 × 10-4 189
900 1.85 × 10-4 213
1000 2.06 × 10-4 237
2000 4.12 × 10-4 474
3000 6.18 × 10-4 710
4000 8.24 × 10-4 947
5000 0.00103 1180
6000 0.00124 1420
7000 0.00144 1660
8000 0.00165 1890
9000 0.00185 2130
1.00 × 104 0.00206 2370
2.00 × 104 0.00412 4740
3.00 × 104 0.00618 7100
4.00 × 104 0.00824 9470
5.00 × 104 0.0103 1.18 × 104
6.00 × 104 0.0124 1.42 × 104
7.00 × 104 0.0144 1.66 × 104
8.00 × 104 0.0165 1.89 × 104
9.00 × 104 0.0185 2.13 × 104
1.00 × 105 0.0206 2.37 × 104
2.00 × 105 0.0412 4.74 × 104
3.00 × 105 0.0618 7.10 × 104
4.00 × 105 0.0824 9.47 × 104
5.00 × 105 0.103 1.18 × 105
6.00 × 105 0.124 1.42 × 105
7.00 × 105 0.144 1.66 × 105
8.00 × 105 0.165 1.89 × 105
9.00 × 105 0.185 2.13 × 105
1.00 × 106 0.206 2.37 × 105
1.25 × 106 0.259 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 2.34 × 10-4 67.2
80.0 2.64 × 10-4 75.8
90.0 2.97 × 10-4 85.2
100 3.30 × 10-4 94.7
200 6.59 × 10-4 189
300 9.89 × 10-4 284
400 0.00132 379
500 0.00165 474
600 0.00198 568
700 0.00231 663
800 0.00264 758
900 0.00297 852
1000 0.00330 947
2000 0.00659 1890
3000 0.00989 2840
4000 0.0132 3790
5000 0.0165 4740
6000 0.0198 5680
7000 0.0231 6630
8000 0.0264 7580
9000 0.0297 8520
1.00 × 104 0.0330 9470
2.00 × 104 0.0659 1.89 × 104
3.00 × 104 0.0989 2.84 × 104
4.00 × 104 0.132 3.79 × 104
5.00 × 104 0.165 4.74 × 104
6.00 × 104 0.198 5.68 × 104
7.00 × 104 0.231 6.63 × 104
8.00 × 104 0.264 7.58 × 104
9.00 × 104 0.297 8.52 × 104
1.00 × 105 0.330 9.47 × 104
2.00 × 105 0.659 1.89 × 105
3.00 × 105 0.989 2.84 × 105
3.14 × 105 1.03 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.00119 151
80.0 0.00134 170
90.0 0.00150 192
100 0.00167 213
200 0.00334 426
300 0.00501 639
400 0.00668 852
500 0.00835 1070
600 0.0100 1280
700 0.0117 1490
800 0.0134 1700
900 0.0150 1920
1000 0.0167 2130
2000 0.0334 4260
3000 0.0501 6390
4000 0.0668 8520
5000 0.0835 1.07 × 104
6000 0.100 1.28 × 104
7000 0.117 1.49 × 104
8000 0.134 1.70 × 104
9000 0.150 1.92 × 104
1.00 × 104 0.167 2.13 × 104
2.00 × 104 0.334 4.26 × 104
3.00 × 104 0.501 6.39 × 104
4.00 × 104 0.668 8.52 × 104
5.00 × 104 0.835 1.07 × 105
6.00 × 104 1.00 1.28 × 105
7.00 × 104 1.17 1.49 × 105
8.00 × 104 1.34 1.70 × 105
9.00 × 104 1.50 1.92 × 105
1.00 × 105 1.67 2.13 × 105
1.39 × 105 2.33 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.00375 269
80.0 0.00422 303
90.0 0.00475 341
100 0.00528 379
200 0.0106 758
300 0.0158 1140
400 0.0211 1520
500 0.0264 1890
600 0.0317 2270
700 0.0369 2650
800 0.0422 3030
900 0.0475 3410
1000 0.0528 3790
2000 0.106 7580
3000 0.158 1.14 × 104
4000 0.211 1.52 × 104
5000 0.264 1.89 × 104
6000 0.317 2.27 × 104
7000 0.369 2.65 × 104
8000 0.422 3.03 × 104
9000 0.475 3.41 × 104
1.00 × 104 0.528 3.79 × 104
2.00 × 104 1.06 7.58 × 104
3.00 × 104 1.58 1.14 × 105
4.00 × 104 2.11 1.52 × 105
5.00 × 104 2.64 1.89 × 105
6.00 × 104 3.17 2.27 × 105
7.00 × 104 3.69 2.65 × 105
7.84 × 104 4.14 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.00915 420
80.0 0.0103 474
90.0 0.0116 533
100 0.0129 592
200 0.0258 1180
300 0.0386 1780
400 0.0515 2370
500 0.0644 2960
600 0.0773 3550
700 0.0902 4140
800 0.103 4740
900 0.116 5330
1000 0.129 5920
2000 0.258 1.18 × 104
3000 0.386 1.78 × 104
4000 0.515 2.37 × 104
5000 0.644 2.96 × 104
6000 0.773 3.55 × 104
7000 0.902 4.14 × 104
8000 1.03 4.74 × 104
9000 1.16 5.33 × 104
1.00 × 104 1.29 5.92 × 104
2.00 × 104 2.58 1.18 × 105
3.00 × 104 3.86 1.78 × 105
4.00 × 104 5.15 2.37 × 105
5.00 × 104 6.44 2.96 × 105
5.02 × 104 6.46 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.0190 605
80.0 0.0214 682
90.0 0.0240 767
100 0.0267 852
200 0.0534 1700
300 0.0801 2560
400 0.107 3410
500 0.134 4260
600 0.160 5110
700 0.187 5970
800 0.214 6820
900 0.240 7670
1000 0.267 8520
2000 0.534 1.70 × 104
3000 0.801 2.56 × 104
4000 1.07 3.41 × 104
5000 1.34 4.26 × 104
6000 1.60 5.11 × 104
7000 1.87 5.97 × 104
8000 2.14 6.82 × 104
9000 2.40 7.67 × 104
1.00 × 104 2.67 8.52 × 104
2.00 × 104 5.34 1.70 × 105
3.00 × 104 8.01 2.56 × 105
3.48 × 104 9.31 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.0599 1080
80.0 0.0675 1210
90.0 0.0760 1360
100 0.0844 1520
200 0.169 3030
300 0.253 4550
400 0.338 6060
500 0.422 7580
600 0.506 9090
700 0.591 1.06 × 104
800 0.675 1.21 × 104
900 0.760 1.36 × 104
1000 0.844 1.52 × 104
2000 1.69 3.03 × 104
3000 2.53 4.55 × 104
4000 3.38 6.06 × 104
5000 4.22 7.58 × 104
6000 5.06 9.09 × 104
7000 5.91 1.06 × 105
8000 6.75 1.21 × 105
9000 7.60 1.36 × 105
1.00 × 104 8.44 1.52 × 105
1.96 × 104 16.5 2.97 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.146 1680
80.0 0.165 1890
90.0 0.185 2130
100 0.206 2370
200 0.412 4740
300 0.618 7100
400 0.824 9470
500 1.03 1.18 × 104
600 1.24 1.42 × 104
700 1.44 1.66 × 104
800 1.65 1.89 × 104
900 1.85 2.13 × 104
1000 2.06 2.37 × 104
2000 4.12 4.74 × 104
3000 6.18 7.10 × 104
4000 8.24 9.47 × 104
5000 10.3 1.18 × 105
6000 12.4 1.42 × 105
7000 14.4 1.66 × 105
8000 16.5 1.89 × 105
8960 18.5 2.12 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.303 2420
80.0 0.342 2730
90.0 0.385 3070
100 0.427 3410
200 0.855 6820
300 1.28 1.02 × 104
400 1.71 1.36 × 104
500 2.14 1.70 × 104
600 2.56 2.05 × 104
700 2.99 2.39 × 104
800 3.42 2.73 × 104
900 3.85 3.07 × 104
1000 4.27 3.41 × 104
2000 8.55 6.82 × 104
3000 12.8 1.02 × 105
4000 17.1 1.36 × 105
4320 18.5 1.47 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.562 3300
80.0 0.633 3710
90.0 0.713 4180
100 0.792 4640
200 1.58 9280
300 2.38 1.39 × 104
400 3.17 1.86 × 104
500 3.96 2.32 × 104
600 4.75 2.78 × 104
700 5.54 3.25 × 104
800 6.33 3.71 × 104
900 7.13 4.18 × 104
1000 7.92 4.64 × 104
2000 15.8 9.28 × 104
2330 18.5 1.08 × 105
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 0.959 4300
80.0 1.08 4850
90.0 1.22 5460
100 1.35 6060
200 2.70 1.21 × 104
300 4.05 1.82 × 104
400 5.40 2.42 × 104
500 6.75 3.03 × 104
600 8.10 3.64 × 104
700 9.45 4.24 × 104
800 10.8 4.85 × 104
900 12.2 5.46 × 104
1000 13.5 6.06 × 104
1370 18.5 8.29 × 104
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 1.54 5450
80.0 1.73 6140
90.0 1.95 6900
100 2.16 7670
200 4.33 1.53 × 104
300 6.49 2.30 × 104
400 8.65 3.07 × 104
500 10.8 3.84 × 104
600 13.0 4.60 × 104
700 15.1 5.37 × 104
800 17.3 6.14 × 104
854 18.5 6.55 × 104
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 100 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 2.34 6720
80.0 2.64 7580
90.0 2.97 8520
100 3.30 9470
200 6.59 1.89 × 104
300 9.89 2.84 × 104
400 13.2 3.79 × 104
500 16.5 4.74 × 104
560 18.5 5.31 × 104
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 125 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 5.72 1.05 × 104
80.0 6.44 1.18 × 104
90.0 7.25 1.33 × 104
100 8.05 1.48 × 104
200 16.1 2.96 × 104
229 18.5 3.40 × 104
Steel I Beam: W18 × 71 (Wide Flange 18 inch tall × 71 lbf/ft)
L = 150 ft
P (lbf/ft) w_max (in) stress_max (psi)
71.0 11.9 1.51 × 104
80.0 13.4 1.70 × 104
90.0 15.0 1.92 × 104
100 16.7 2.13 × 104
111 18.5 2.36 × 104
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Negotiate Your Salary

Learn the best principles to negotiate the salary you deserve!

STEM Career Outlook

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

Metal 3D Printing Design Guide

Direct Metal Laser Sintering (DMLS) 3D printing for parts with reduced cost and little waste.

Essentials of Manufacturing

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

more publications