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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Two 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 two equal spans, we compute the displacement at the middle of each span w_mid and the maximum normal stress stress_max occuring at the center support 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 1.45 × 10-6 7.57
80.0 1.64 × 10-6 8.52
90.0 1.84 × 10-6 9.59
100 2.05 × 10-6 10.7
200 4.09 × 10-6 21.3
300 6.14 × 10-6 32.0
400 8.18 × 10-6 42.6
500 1.02 × 10-5 53.3
600 1.23 × 10-5 63.9
700 1.43 × 10-5 74.6
800 1.64 × 10-5 85.2
900 1.84 × 10-5 95.9
1000 2.05 × 10-5 107
2000 4.09 × 10-5 213
3000 6.14 × 10-5 320
4000 8.18 × 10-5 426
5000 1.02 × 10-4 533
6000 1.23 × 10-4 639
7000 1.43 × 10-4 746
8000 1.64 × 10-4 852
9000 1.84 × 10-4 959
1.00 × 104 2.05 × 10-4 1070
2.00 × 104 4.09 × 10-4 2130
3.00 × 104 6.14 × 10-4 3200
4.00 × 104 8.18 × 10-4 4260
5.00 × 104 0.00102 5330
6.00 × 104 0.00123 6390
7.00 × 104 0.00143 7460
8.00 × 104 0.00164 8520
9.00 × 104 0.00184 9590
1.00 × 105 0.00205 1.07 × 104
2.00 × 105 0.00409 2.13 × 104
3.00 × 105 0.00614 3.20 × 104
4.00 × 105 0.00818 4.26 × 104
5.00 × 105 0.0102 5.33 × 104
6.00 × 105 0.0123 6.39 × 104
7.00 × 105 0.0143 7.46 × 104
8.00 × 105 0.0164 8.52 × 104
9.00 × 105 0.0184 9.59 × 104
1.00 × 106 0.0205 1.07 × 105
2.00 × 106 0.0409 2.13 × 105
2.79 × 106 0.0570 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 1.12 × 10-5 21.0
80.0 1.26 × 10-5 23.7
90.0 1.42 × 10-5 26.6
100 1.58 × 10-5 29.6
200 3.16 × 10-5 59.2
300 4.74 × 10-5 88.8
400 6.31 × 10-5 118
500 7.89 × 10-5 148
600 9.47 × 10-5 178
700 1.10 × 10-4 207
800 1.26 × 10-4 237
900 1.42 × 10-4 266
1000 1.58 × 10-4 296
2000 3.16 × 10-4 592
3000 4.74 × 10-4 888
4000 6.31 × 10-4 1180
5000 7.89 × 10-4 1480
6000 9.47 × 10-4 1780
7000 0.00110 2070
8000 0.00126 2370
9000 0.00142 2660
1.00 × 104 0.00158 2960
2.00 × 104 0.00316 5920
3.00 × 104 0.00474 8880
4.00 × 104 0.00631 1.18 × 104
5.00 × 104 0.00789 1.48 × 104
6.00 × 104 0.00947 1.78 × 104
7.00 × 104 0.0110 2.07 × 104
8.00 × 104 0.0126 2.37 × 104
9.00 × 104 0.0142 2.66 × 104
1.00 × 105 0.0158 2.96 × 104
2.00 × 105 0.0316 5.92 × 104
3.00 × 105 0.0474 8.88 × 104
4.00 × 105 0.0631 1.18 × 105
5.00 × 105 0.0789 1.48 × 105
6.00 × 105 0.0947 1.78 × 105
7.00 × 105 0.110 2.07 × 105
8.00 × 105 0.126 2.37 × 105
9.00 × 105 0.142 2.66 × 105
1.00 × 106 0.158 2.96 × 105
1.00 × 106 0.158 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 1.79 × 10-4 84.1
80.0 2.02 × 10-4 94.7
90.0 2.27 × 10-4 107
100 2.53 × 10-4 118
200 5.05 × 10-4 237
300 7.58 × 10-4 355
400 0.00101 474
500 0.00126 592
600 0.00152 710
700 0.00177 829
800 0.00202 947
900 0.00227 1070
1000 0.00253 1180
2000 0.00505 2370
3000 0.00758 3550
4000 0.0101 4740
5000 0.0126 5920
6000 0.0152 7100
7000 0.0177 8290
8000 0.0202 9470
9000 0.0227 1.07 × 104
1.00 × 104 0.0253 1.18 × 104
2.00 × 104 0.0505 2.37 × 104
3.00 × 104 0.0758 3.55 × 104
4.00 × 104 0.101 4.74 × 104
5.00 × 104 0.126 5.92 × 104
6.00 × 104 0.152 7.10 × 104
7.00 × 104 0.177 8.29 × 104
8.00 × 104 0.202 9.47 × 104
9.00 × 104 0.227 1.07 × 105
1.00 × 105 0.253 1.18 × 105
2.00 × 105 0.505 2.37 × 105
2.51 × 105 0.634 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 9.08 × 10-4 189
80.0 0.00102 213
90.0 0.00115 240
100 0.00128 266
200 0.00256 533
300 0.00384 799
400 0.00511 1070
500 0.00639 1330
600 0.00767 1600
700 0.00895 1860
800 0.0102 2130
900 0.0115 2400
1000 0.0128 2660
2000 0.0256 5330
3000 0.0384 7990
4000 0.0511 1.07 × 104
5000 0.0639 1.33 × 104
6000 0.0767 1.60 × 104
7000 0.0895 1.86 × 104
8000 0.102 2.13 × 104
9000 0.115 2.40 × 104
1.00 × 104 0.128 2.66 × 104
2.00 × 104 0.256 5.33 × 104
3.00 × 104 0.384 7.99 × 104
4.00 × 104 0.511 1.07 × 105
5.00 × 104 0.639 1.33 × 105
6.00 × 104 0.767 1.60 × 105
7.00 × 104 0.895 1.86 × 105
8.00 × 104 1.02 2.13 × 105
9.00 × 104 1.15 2.40 × 105
1.00 × 105 1.28 2.66 × 105
1.12 × 105 1.43 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 0.00287 336
80.0 0.00323 379
90.0 0.00364 426
100 0.00404 474
200 0.00808 947
300 0.0121 1420
400 0.0162 1890
500 0.0202 2370
600 0.0242 2840
700 0.0283 3320
800 0.0323 3790
900 0.0364 4260
1000 0.0404 4740
2000 0.0808 9470
3000 0.121 1.42 × 104
4000 0.162 1.89 × 104
5000 0.202 2.37 × 104
6000 0.242 2.84 × 104
7000 0.283 3.32 × 104
8000 0.323 3.79 × 104
9000 0.364 4.26 × 104
1.00 × 104 0.404 4.74 × 104
2.00 × 104 0.808 9.47 × 104
3.00 × 104 1.21 1.42 × 105
4.00 × 104 1.62 1.89 × 105
5.00 × 104 2.02 2.37 × 105
6.00 × 104 2.42 2.84 × 105
6.27 × 104 2.53 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 0.00700 525
80.0 0.00789 592
90.0 0.00888 666
100 0.00987 740
200 0.0197 1480
300 0.0296 2220
400 0.0395 2960
500 0.0493 3700
600 0.0592 4440
700 0.0691 5180
800 0.0789 5920
900 0.0888 6660
1000 0.0987 7400
2000 0.197 1.48 × 104
3000 0.296 2.22 × 104
4000 0.395 2.96 × 104
5000 0.493 3.70 × 104
6000 0.592 4.44 × 104
7000 0.691 5.18 × 104
8000 0.789 5.92 × 104
9000 0.888 6.66 × 104
1.00 × 104 0.987 7.40 × 104
2.00 × 104 1.97 1.48 × 105
3.00 × 104 2.96 2.22 × 105
4.00 × 104 3.95 2.96 × 105
4.01 × 104 3.96 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 0.0145 757
80.0 0.0164 852
90.0 0.0184 959
100 0.0205 1070
200 0.0409 2130
300 0.0614 3200
400 0.0818 4260
500 0.102 5330
600 0.123 6390
700 0.143 7460
800 0.164 8520
900 0.184 9590
1000 0.205 1.07 × 104
2000 0.409 2.13 × 104
3000 0.614 3.20 × 104
4000 0.818 4.26 × 104
5000 1.02 5.33 × 104
6000 1.23 6.39 × 104
7000 1.43 7.46 × 104
8000 1.64 8.52 × 104
9000 1.84 9.59 × 104
1.00 × 104 2.05 1.07 × 105
2.00 × 104 4.09 2.13 × 105
2.79 × 104 5.70 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 0.0459 1340
80.0 0.0517 1520
90.0 0.0582 1700
100 0.0647 1890
200 0.129 3790
300 0.194 5680
400 0.259 7580
500 0.323 9470
600 0.388 1.14 × 104
700 0.453 1.33 × 104
800 0.517 1.52 × 104
900 0.582 1.70 × 104
1000 0.647 1.89 × 104
2000 1.29 3.79 × 104
3000 1.94 5.68 × 104
4000 2.59 7.58 × 104
5000 3.23 9.47 × 104
6000 3.88 1.14 × 105
7000 4.53 1.33 × 105
8000 5.17 1.52 × 105
9000 5.82 1.70 × 105
1.00 × 104 6.47 1.89 × 105
1.57 × 104 10.1 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 0.112 2100
80.0 0.126 2370
90.0 0.142 2660
100 0.158 2960
200 0.316 5920
300 0.474 8880
400 0.631 1.18 × 104
500 0.789 1.48 × 104
600 0.947 1.78 × 104
700 1.10 2.07 × 104
800 1.26 2.37 × 104
900 1.42 2.66 × 104
1000 1.58 2.96 × 104
2000 3.16 5.92 × 104
3000 4.74 8.88 × 104
4000 6.31 1.18 × 105
5000 7.89 1.48 × 105
6000 9.47 1.78 × 105
7000 11.0 2.07 × 105
8000 12.6 2.37 × 105
9000 14.2 2.66 × 105
1.00 × 104 15.8 2.96 × 105
1.00 × 104 15.8 2.97 × 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 0.232 3030
80.0 0.262 3410
90.0 0.295 3840
100 0.327 4260
200 0.655 8520
300 0.982 1.28 × 104
400 1.31 1.70 × 104
500 1.64 2.13 × 104
600 1.96 2.56 × 104
700 2.29 2.98 × 104
800 2.62 3.41 × 104
900 2.95 3.84 × 104
1000 3.27 4.26 × 104
2000 6.55 8.52 × 104
3000 9.82 1.28 × 105
4000 13.1 1.70 × 105
5000 16.4 2.13 × 105
5640 18.5 2.41 × 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 0.431 4120
80.0 0.485 4640
90.0 0.546 5220
100 0.606 5800
200 1.21 1.16 × 104
300 1.82 1.74 × 104
400 2.43 2.32 × 104
500 3.03 2.90 × 104
600 3.64 3.48 × 104
700 4.24 4.06 × 104
800 4.85 4.64 × 104
900 5.46 5.22 × 104
1000 6.06 5.80 × 104
2000 12.1 1.16 × 105
3000 18.2 1.74 × 105
3050 18.5 1.77 × 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 0.734 5380
80.0 0.828 6060
90.0 0.931 6820
100 1.03 7580
200 2.07 1.52 × 104
300 3.10 2.27 × 104
400 4.14 3.03 × 104
500 5.17 3.79 × 104
600 6.21 4.55 × 104
700 7.24 5.30 × 104
800 8.28 6.06 × 104
900 9.31 6.82 × 104
1000 10.3 7.58 × 104
1790 18.5 1.35 × 105
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 1.18 6810
80.0 1.33 7670
90.0 1.49 8630
100 1.66 9590
200 3.31 1.92 × 104
300 4.97 2.88 × 104
400 6.63 3.84 × 104
500 8.29 4.80 × 104
600 9.94 5.75 × 104
700 11.6 6.71 × 104
800 13.3 7.67 × 104
900 14.9 8.63 × 104
1000 16.6 9.59 × 104
1110 18.5 1.07 × 105
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 1.79 8410
80.0 2.02 9470
90.0 2.27 1.07 × 104
100 2.53 1.18 × 104
200 5.05 2.37 × 104
300 7.58 3.55 × 104
400 10.1 4.74 × 104
500 12.6 5.92 × 104
600 15.2 7.10 × 104
700 17.7 8.29 × 104
731 18.5 8.66 × 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 4.38 1.31 × 104
80.0 4.93 1.48 × 104
90.0 5.55 1.66 × 104
100 6.17 1.85 × 104
200 12.3 3.70 × 104
300 18.5 5.54 × 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 9.08 1.89 × 104
80.0 10.2 2.13 × 104
90.0 11.5 2.40 × 104
100 12.8 2.66 × 104
144 18.5 3.85 × 104
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STEM Career Outlook

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

Negotiate Your Salary

Learn the best principles to negotiate the salary you deserve!

Mechanical Engineers Outlook

Guide for those interested in becoming a mechanical engineer. Includes qualifications, pay, and job duties.

CNC Machining Design Guide

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

more publications