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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Three Equal Spans » Wide Flange Steel I Beam » W18 × 50
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 = 800 in4) for the W18 × 50 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 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 1.95 × 10-6 6.07
60.0 2.34 × 10-6 7.29
70.0 2.73 × 10-6 8.50
80.0 3.12 × 10-6 9.71
90.0 3.52 × 10-6 10.9
100 3.91 × 10-6 12.1
200 7.81 × 10-6 24.3
300 1.17 × 10-5 36.4
400 1.56 × 10-5 48.6
500 1.95 × 10-5 60.7
600 2.34 × 10-5 72.9
700 2.73 × 10-5 85.0
800 3.12 × 10-5 97.1
900 3.52 × 10-5 109
1000 3.91 × 10-5 121
2000 7.81 × 10-5 243
3000 1.17 × 10-4 364
4000 1.56 × 10-4 486
5000 1.95 × 10-4 607
6000 2.34 × 10-4 729
7000 2.73 × 10-4 850
8000 3.12 × 10-4 971
9000 3.52 × 10-4 1090
1.00 × 104 3.91 × 10-4 1210
2.00 × 104 7.81 × 10-4 2430
3.00 × 104 0.00117 3640
4.00 × 104 0.00156 4860
5.00 × 104 0.00195 6070
6.00 × 104 0.00234 7290
7.00 × 104 0.00273 8500
8.00 × 104 0.00312 9710
9.00 × 104 0.00352 1.09 × 104
1.00 × 105 0.00391 1.21 × 104
2.00 × 105 0.00781 2.43 × 104
3.00 × 105 0.0117 3.64 × 104
4.00 × 105 0.0156 4.86 × 104
5.00 × 105 0.0195 6.07 × 104
6.00 × 105 0.0234 7.29 × 104
7.00 × 105 0.0273 8.50 × 104
8.00 × 105 0.0312 9.71 × 104
9.00 × 105 0.0352 1.09 × 105
1.00 × 106 0.0391 1.21 × 105
2.00 × 106 0.0781 2.43 × 105
2.45 × 106 0.0955 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 1.51 × 10-5 16.9
60.0 1.81 × 10-5 20.2
70.0 2.11 × 10-5 23.6
80.0 2.41 × 10-5 27.0
90.0 2.71 × 10-5 30.4
100 3.01 × 10-5 33.7
200 6.03 × 10-5 67.5
300 9.04 × 10-5 101
400 1.21 × 10-4 135
500 1.51 × 10-4 169
600 1.81 × 10-4 202
700 2.11 × 10-4 236
800 2.41 × 10-4 270
900 2.71 × 10-4 304
1000 3.01 × 10-4 337
2000 6.03 × 10-4 675
3000 9.04 × 10-4 1010
4000 0.00121 1350
5000 0.00151 1690
6000 0.00181 2020
7000 0.00211 2360
8000 0.00241 2700
9000 0.00271 3040
1.00 × 104 0.00301 3370
2.00 × 104 0.00603 6750
3.00 × 104 0.00904 1.01 × 104
4.00 × 104 0.0121 1.35 × 104
5.00 × 104 0.0151 1.69 × 104
6.00 × 104 0.0181 2.02 × 104
7.00 × 104 0.0211 2.36 × 104
8.00 × 104 0.0241 2.70 × 104
9.00 × 104 0.0271 3.04 × 104
1.00 × 105 0.0301 3.37 × 104
2.00 × 105 0.0603 6.75 × 104
3.00 × 105 0.0904 1.01 × 105
4.00 × 105 0.121 1.35 × 105
5.00 × 105 0.151 1.69 × 105
6.00 × 105 0.181 2.02 × 105
7.00 × 105 0.211 2.36 × 105
8.00 × 105 0.241 2.70 × 105
8.81 × 105 0.265 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 2.41 × 10-4 67.5
60.0 2.89 × 10-4 81.0
70.0 3.38 × 10-4 94.4
80.0 3.86 × 10-4 108
90.0 4.34 × 10-4 121
100 4.82 × 10-4 135
200 9.64 × 10-4 270
300 0.00145 405
400 0.00193 540
500 0.00241 675
600 0.00289 810
700 0.00338 944
800 0.00386 1080
900 0.00434 1210
1000 0.00482 1350
2000 0.00964 2700
3000 0.0145 4050
4000 0.0193 5400
5000 0.0241 6750
6000 0.0289 8100
7000 0.0338 9440
8000 0.0386 1.08 × 104
9000 0.0434 1.21 × 104
1.00 × 104 0.0482 1.35 × 104
2.00 × 104 0.0964 2.70 × 104
3.00 × 104 0.145 4.05 × 104
4.00 × 104 0.193 5.40 × 104
5.00 × 104 0.241 6.75 × 104
6.00 × 104 0.289 8.10 × 104
7.00 × 104 0.338 9.44 × 104
8.00 × 104 0.386 1.08 × 105
9.00 × 104 0.434 1.21 × 105
1.00 × 105 0.482 1.35 × 105
2.00 × 105 0.964 2.70 × 105
2.20 × 105 1.06 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.00122 152
60.0 0.00146 182
70.0 0.00171 213
80.0 0.00195 243
90.0 0.00220 273
100 0.00244 304
200 0.00488 607
300 0.00732 911
400 0.00977 1210
500 0.0122 1520
600 0.0146 1820
700 0.0171 2130
800 0.0195 2430
900 0.0220 2730
1000 0.0244 3040
2000 0.0488 6070
3000 0.0732 9110
4000 0.0977 1.21 × 104
5000 0.122 1.52 × 104
6000 0.146 1.82 × 104
7000 0.171 2.13 × 104
8000 0.195 2.43 × 104
9000 0.220 2.73 × 104
1.00 × 104 0.244 3.04 × 104
2.00 × 104 0.488 6.07 × 104
3.00 × 104 0.732 9.11 × 104
4.00 × 104 0.977 1.21 × 105
5.00 × 104 1.22 1.52 × 105
6.00 × 104 1.46 1.82 × 105
7.00 × 104 1.71 2.13 × 105
8.00 × 104 1.95 2.43 × 105
9.00 × 104 2.20 2.73 × 105
9.78 × 104 2.39 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.00386 270
60.0 0.00463 324
70.0 0.00540 378
80.0 0.00617 432
90.0 0.00694 486
100 0.00772 540
200 0.0154 1080
300 0.0231 1620
400 0.0309 2160
500 0.0386 2700
600 0.0463 3240
700 0.0540 3780
800 0.0617 4320
900 0.0694 4860
1000 0.0772 5400
2000 0.154 1.08 × 104
3000 0.231 1.62 × 104
4000 0.309 2.16 × 104
5000 0.386 2.70 × 104
6000 0.463 3.24 × 104
7000 0.540 3.78 × 104
8000 0.617 4.32 × 104
9000 0.694 4.86 × 104
1.00 × 104 0.772 5.40 × 104
2.00 × 104 1.54 1.08 × 105
3.00 × 104 2.31 1.62 × 105
4.00 × 104 3.09 2.16 × 105
5.00 × 104 3.86 2.70 × 105
5.50 × 104 4.25 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.00942 422
60.0 0.0113 506
70.0 0.0132 590
80.0 0.0151 675
90.0 0.0170 759
100 0.0188 843
200 0.0377 1690
300 0.0565 2530
400 0.0753 3370
500 0.0942 4220
600 0.113 5060
700 0.132 5900
800 0.151 6750
900 0.170 7590
1000 0.188 8430
2000 0.377 1.69 × 104
3000 0.565 2.53 × 104
4000 0.753 3.37 × 104
5000 0.942 4.22 × 104
6000 1.13 5.06 × 104
7000 1.32 5.90 × 104
8000 1.51 6.75 × 104
9000 1.70 7.59 × 104
1.00 × 104 1.88 8.43 × 104
2.00 × 104 3.77 1.69 × 105
3.00 × 104 5.65 2.53 × 105
3.52 × 104 6.64 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.0195 607
60.0 0.0234 729
70.0 0.0273 850
80.0 0.0312 971
90.0 0.0352 1090
100 0.0391 1210
200 0.0781 2430
300 0.117 3640
400 0.156 4860
500 0.195 6070
600 0.234 7290
700 0.273 8500
800 0.312 9710
900 0.352 1.09 × 104
1000 0.391 1.21 × 104
2000 0.781 2.43 × 104
3000 1.17 3.64 × 104
4000 1.56 4.86 × 104
5000 1.95 6.07 × 104
6000 2.34 7.29 × 104
7000 2.73 8.50 × 104
8000 3.12 9.71 × 104
9000 3.52 1.09 × 105
1.00 × 104 3.91 1.21 × 105
2.00 × 104 7.81 2.43 × 105
2.45 × 104 9.55 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.0617 1080
60.0 0.0741 1300
70.0 0.0864 1510
80.0 0.0988 1730
90.0 0.111 1940
100 0.123 2160
200 0.247 4320
300 0.370 6480
400 0.494 8640
500 0.617 1.08 × 104
600 0.741 1.30 × 104
700 0.864 1.51 × 104
800 0.988 1.73 × 104
900 1.11 1.94 × 104
1000 1.23 2.16 × 104
2000 2.47 4.32 × 104
3000 3.70 6.48 × 104
4000 4.94 8.64 × 104
5000 6.17 1.08 × 105
6000 7.41 1.30 × 105
7000 8.64 1.51 × 105
8000 9.88 1.73 × 105
9000 11.1 1.94 × 105
1.00 × 104 12.3 2.16 × 105
1.38 × 104 17.0 2.97 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.151 1690
60.0 0.181 2020
70.0 0.211 2360
80.0 0.241 2700
90.0 0.271 3040
100 0.301 3370
200 0.603 6750
300 0.904 1.01 × 104
400 1.21 1.35 × 104
500 1.51 1.69 × 104
600 1.81 2.02 × 104
700 2.11 2.36 × 104
800 2.41 2.70 × 104
900 2.71 3.04 × 104
1000 3.01 3.37 × 104
2000 6.03 6.75 × 104
3000 9.04 1.01 × 105
4000 12.1 1.35 × 105
5000 15.1 1.69 × 105
5970 18.0 2.01 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.312 2430
60.0 0.375 2910
70.0 0.437 3400
80.0 0.500 3890
90.0 0.562 4370
100 0.625 4860
200 1.25 9710
300 1.87 1.46 × 104
400 2.50 1.94 × 104
500 3.12 2.43 × 104
600 3.75 2.91 × 104
700 4.37 3.40 × 104
800 5.00 3.89 × 104
900 5.62 4.37 × 104
1000 6.25 4.86 × 104
2000 12.5 9.71 × 104
2880 18.0 1.40 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.579 3310
60.0 0.695 3970
70.0 0.810 4630
80.0 0.926 5290
90.0 1.04 5950
100 1.16 6610
200 2.32 1.32 × 104
300 3.47 1.98 × 104
400 4.63 2.64 × 104
500 5.79 3.31 × 104
600 6.95 3.97 × 104
700 8.10 4.63 × 104
800 9.26 5.29 × 104
900 10.4 5.95 × 104
1000 11.6 6.61 × 104
1550 18.0 1.03 × 105
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 0.988 4320
60.0 1.19 5180
70.0 1.38 6040
80.0 1.58 6910
90.0 1.78 7770
100 1.98 8640
200 3.95 1.73 × 104
300 5.93 2.59 × 104
400 7.90 3.45 × 104
500 9.88 4.32 × 104
600 11.9 5.18 × 104
700 13.8 6.04 × 104
800 15.8 6.91 × 104
900 17.8 7.77 × 104
911 18.0 7.86 × 104
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 1.58 5460
60.0 1.90 6560
70.0 2.21 7650
80.0 2.53 8740
90.0 2.85 9840
100 3.16 1.09 × 104
200 6.33 2.19 × 104
300 9.49 3.28 × 104
400 12.7 4.37 × 104
500 15.8 5.46 × 104
569 18.0 6.21 × 104
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 100 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 2.41 6750
60.0 2.89 8100
70.0 3.38 9440
80.0 3.86 1.08 × 104
90.0 4.34 1.21 × 104
100 4.82 1.35 × 104
200 9.64 2.70 × 104
300 14.5 4.05 × 104
373 18.0 5.03 × 104
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 125 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 5.89 1.05 × 104
60.0 7.06 1.26 × 104
70.0 8.24 1.48 × 104
80.0 9.42 1.69 × 104
90.0 10.6 1.90 × 104
100 11.8 2.11 × 104
153 18.0 3.22 × 104
Steel I Beam: W18 × 50 (Wide Flange 18 inch tall × 50 lbf/ft)
L = 150 ft
P (lbf/ft) w_max (in) stress_max (psi)
50.0 12.2 1.52 × 104
60.0 14.6 1.82 × 104
70.0 17.1 2.13 × 104
73.7 18.0 2.24 × 104
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