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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Three Equal Spans » Wide Flange Steel I Beam » W18 × 35
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 = 510 in4) for the W18 × 35 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 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 2.14 × 10-6 6.56
40.0 2.45 × 10-6 7.50
50.0 3.06 × 10-6 9.37
60.0 3.68 × 10-6 11.2
70.0 4.29 × 10-6 13.1
80.0 4.90 × 10-6 15.0
90.0 5.51 × 10-6 16.9
100 6.13 × 10-6 18.7
200 1.23 × 10-5 37.5
300 1.84 × 10-5 56.2
400 2.45 × 10-5 75.0
500 3.06 × 10-5 93.7
600 3.68 × 10-5 112
700 4.29 × 10-5 131
800 4.90 × 10-5 150
900 5.51 × 10-5 169
1000 6.13 × 10-5 187
2000 1.23 × 10-4 375
3000 1.84 × 10-4 562
4000 2.45 × 10-4 750
5000 3.06 × 10-4 937
6000 3.68 × 10-4 1120
7000 4.29 × 10-4 1310
8000 4.90 × 10-4 1500
9000 5.51 × 10-4 1690
1.00 × 104 6.13 × 10-4 1870
2.00 × 104 0.00123 3750
3.00 × 104 0.00184 5620
4.00 × 104 0.00245 7500
5.00 × 104 0.00306 9370
6.00 × 104 0.00368 1.12 × 104
7.00 × 104 0.00429 1.31 × 104
8.00 × 104 0.00490 1.50 × 104
9.00 × 104 0.00551 1.69 × 104
1.00 × 105 0.00613 1.87 × 104
2.00 × 105 0.0123 3.75 × 104
3.00 × 105 0.0184 5.62 × 104
4.00 × 105 0.0245 7.50 × 104
5.00 × 105 0.0306 9.37 × 104
6.00 × 105 0.0368 1.12 × 105
7.00 × 105 0.0429 1.31 × 105
8.00 × 105 0.0490 1.50 × 105
9.00 × 105 0.0551 1.69 × 105
1.00 × 106 0.0613 1.87 × 105
1.58 × 106 0.0971 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 1.65 × 10-5 18.2
40.0 1.89 × 10-5 20.8
50.0 2.36 × 10-5 26.0
60.0 2.84 × 10-5 31.2
70.0 3.31 × 10-5 36.4
80.0 3.78 × 10-5 41.6
90.0 4.26 × 10-5 46.9
100 4.73 × 10-5 52.1
200 9.46 × 10-5 104
300 1.42 × 10-4 156
400 1.89 × 10-4 208
500 2.36 × 10-4 260
600 2.84 × 10-4 312
700 3.31 × 10-4 364
800 3.78 × 10-4 416
900 4.26 × 10-4 469
1000 4.73 × 10-4 521
2000 9.46 × 10-4 1040
3000 0.00142 1560
4000 0.00189 2080
5000 0.00236 2600
6000 0.00284 3120
7000 0.00331 3640
8000 0.00378 4160
9000 0.00426 4690
1.00 × 104 0.00473 5210
2.00 × 104 0.00946 1.04 × 104
3.00 × 104 0.0142 1.56 × 104
4.00 × 104 0.0189 2.08 × 104
5.00 × 104 0.0236 2.60 × 104
6.00 × 104 0.0284 3.12 × 104
7.00 × 104 0.0331 3.64 × 104
8.00 × 104 0.0378 4.16 × 104
9.00 × 104 0.0426 4.69 × 104
1.00 × 105 0.0473 5.21 × 104
2.00 × 105 0.0946 1.04 × 105
3.00 × 105 0.142 1.56 × 105
4.00 × 105 0.189 2.08 × 105
5.00 × 105 0.236 2.60 × 105
5.71 × 105 0.270 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 2.65 × 10-4 72.9
40.0 3.03 × 10-4 83.3
50.0 3.78 × 10-4 104
60.0 4.54 × 10-4 125
70.0 5.30 × 10-4 146
80.0 6.05 × 10-4 167
90.0 6.81 × 10-4 187
100 7.56 × 10-4 208
200 0.00151 416
300 0.00227 625
400 0.00303 833
500 0.00378 1040
600 0.00454 1250
700 0.00530 1460
800 0.00605 1670
900 0.00681 1870
1000 0.00756 2080
2000 0.0151 4160
3000 0.0227 6250
4000 0.0303 8330
5000 0.0378 1.04 × 104
6000 0.0454 1.25 × 104
7000 0.0530 1.46 × 104
8000 0.0605 1.67 × 104
9000 0.0681 1.87 × 104
1.00 × 104 0.0756 2.08 × 104
2.00 × 104 0.151 4.16 × 104
3.00 × 104 0.227 6.25 × 104
4.00 × 104 0.303 8.33 × 104
5.00 × 104 0.378 1.04 × 105
6.00 × 104 0.454 1.25 × 105
7.00 × 104 0.530 1.46 × 105
8.00 × 104 0.605 1.67 × 105
9.00 × 104 0.681 1.87 × 105
1.00 × 105 0.756 2.08 × 105
1.43 × 105 1.08 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.00134 164
40.0 0.00153 187
50.0 0.00191 234
60.0 0.00230 281
70.0 0.00268 328
80.0 0.00306 375
90.0 0.00345 422
100 0.00383 469
200 0.00766 937
300 0.0115 1410
400 0.0153 1870
500 0.0191 2340
600 0.0230 2810
700 0.0268 3280
800 0.0306 3750
900 0.0345 4220
1000 0.0383 4690
2000 0.0766 9370
3000 0.115 1.41 × 104
4000 0.153 1.87 × 104
5000 0.191 2.34 × 104
6000 0.230 2.81 × 104
7000 0.268 3.28 × 104
8000 0.306 3.75 × 104
9000 0.345 4.22 × 104
1.00 × 104 0.383 4.69 × 104
2.00 × 104 0.766 9.37 × 104
3.00 × 104 1.15 1.41 × 105
4.00 × 104 1.53 1.87 × 105
5.00 × 104 1.91 2.34 × 105
6.00 × 104 2.30 2.81 × 105
6.34 × 104 2.43 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.00424 292
40.0 0.00484 333
50.0 0.00605 416
60.0 0.00726 500
70.0 0.00847 583
80.0 0.00968 666
90.0 0.0109 750
100 0.0121 833
200 0.0242 1670
300 0.0363 2500
400 0.0484 3330
500 0.0605 4160
600 0.0726 5000
700 0.0847 5830
800 0.0968 6660
900 0.109 7500
1000 0.121 8330
2000 0.242 1.67 × 104
3000 0.363 2.50 × 104
4000 0.484 3.33 × 104
5000 0.605 4.16 × 104
6000 0.726 5.00 × 104
7000 0.847 5.83 × 104
8000 0.968 6.66 × 104
9000 1.09 7.50 × 104
1.00 × 104 1.21 8.33 × 104
2.00 × 104 2.42 1.67 × 105
3.00 × 104 3.63 2.50 × 105
3.57 × 104 4.32 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.0103 456
40.0 0.0118 521
50.0 0.0148 651
60.0 0.0177 781
70.0 0.0207 911
80.0 0.0236 1040
90.0 0.0266 1170
100 0.0295 1300
200 0.0591 2600
300 0.0886 3900
400 0.118 5210
500 0.148 6510
600 0.177 7810
700 0.207 9110
800 0.236 1.04 × 104
900 0.266 1.17 × 104
1000 0.295 1.30 × 104
2000 0.591 2.60 × 104
3000 0.886 3.90 × 104
4000 1.18 5.21 × 104
5000 1.48 6.51 × 104
6000 1.77 7.81 × 104
7000 2.07 9.11 × 104
8000 2.36 1.04 × 105
9000 2.66 1.17 × 105
1.00 × 104 2.95 1.30 × 105
2.00 × 104 5.91 2.60 × 105
2.28 × 104 6.74 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.0214 656
40.0 0.0245 750
50.0 0.0306 937
60.0 0.0368 1120
70.0 0.0429 1310
80.0 0.0490 1500
90.0 0.0551 1690
100 0.0613 1870
200 0.123 3750
300 0.184 5620
400 0.245 7500
500 0.306 9370
600 0.368 1.12 × 104
700 0.429 1.31 × 104
800 0.490 1.50 × 104
900 0.551 1.69 × 104
1000 0.613 1.87 × 104
2000 1.23 3.75 × 104
3000 1.84 5.62 × 104
4000 2.45 7.50 × 104
5000 3.06 9.37 × 104
6000 3.68 1.12 × 105
7000 4.29 1.31 × 105
8000 4.90 1.50 × 105
9000 5.51 1.69 × 105
1.00 × 104 6.13 1.87 × 105
1.58 × 104 9.71 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.0678 1170
40.0 0.0775 1330
50.0 0.0968 1670
60.0 0.116 2000
70.0 0.136 2330
80.0 0.155 2670
90.0 0.174 3000
100 0.194 3330
200 0.387 6660
300 0.581 10000
400 0.775 1.33 × 104
500 0.968 1.67 × 104
600 1.16 2.00 × 104
700 1.36 2.33 × 104
800 1.55 2.67 × 104
900 1.74 3.00 × 104
1000 1.94 3.33 × 104
2000 3.87 6.66 × 104
3000 5.81 1.00 × 105
4000 7.75 1.33 × 105
5000 9.68 1.67 × 105
6000 11.6 2.00 × 105
7000 13.6 2.33 × 105
8000 15.5 2.67 × 105
8920 17.3 2.97 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.165 1820
40.0 0.189 2080
50.0 0.236 2600
60.0 0.284 3120
70.0 0.331 3640
80.0 0.378 4160
90.0 0.426 4690
100 0.473 5210
200 0.946 1.04 × 104
300 1.42 1.56 × 104
400 1.89 2.08 × 104
500 2.36 2.60 × 104
600 2.84 3.12 × 104
700 3.31 3.64 × 104
800 3.78 4.16 × 104
900 4.26 4.69 × 104
1000 4.73 5.21 × 104
2000 9.46 1.04 × 105
3000 14.2 1.56 × 105
3740 17.7 1.95 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.343 2620
40.0 0.392 3000
50.0 0.490 3750
60.0 0.588 4500
70.0 0.686 5250
80.0 0.784 6000
90.0 0.882 6750
100 0.980 7500
200 1.96 1.50 × 104
300 2.94 2.25 × 104
400 3.92 3.00 × 104
500 4.90 3.75 × 104
600 5.88 4.50 × 104
700 6.86 5.25 × 104
800 7.84 6.00 × 104
900 8.82 6.75 × 104
1000 9.80 7.50 × 104
1810 17.7 1.35 × 105
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 0.636 3570
40.0 0.726 4080
50.0 0.908 5100
60.0 1.09 6120
70.0 1.27 7140
80.0 1.45 8160
90.0 1.63 9180
100 1.82 1.02 × 104
200 3.63 2.04 × 104
300 5.45 3.06 × 104
400 7.26 4.08 × 104
500 9.08 5.10 × 104
600 10.9 6.12 × 104
700 12.7 7.14 × 104
800 14.5 8.16 × 104
900 16.3 9.18 × 104
975 17.7 9.94 × 104
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 1.08 4660
40.0 1.24 5330
50.0 1.55 6660
60.0 1.86 8000
70.0 2.17 9330
80.0 2.48 1.07 × 104
90.0 2.79 1.20 × 104
100 3.10 1.33 × 104
200 6.20 2.67 × 104
300 9.30 4.00 × 104
400 12.4 5.33 × 104
500 15.5 6.66 × 104
571 17.7 7.61 × 104
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 1.74 5900
40.0 1.99 6750
50.0 2.48 8430
60.0 2.98 1.01 × 104
70.0 3.47 1.18 × 104
80.0 3.97 1.35 × 104
90.0 4.47 1.52 × 104
100 4.96 1.69 × 104
200 9.93 3.37 × 104
300 14.9 5.06 × 104
357 17.7 6.02 × 104
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 100 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 2.65 7290
40.0 3.03 8330
50.0 3.78 1.04 × 104
60.0 4.54 1.25 × 104
70.0 5.30 1.46 × 104
80.0 6.05 1.67 × 104
90.0 6.81 1.87 × 104
100 7.56 2.08 × 104
200 15.1 4.16 × 104
234 17.7 4.87 × 104
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 125 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 6.46 1.14 × 104
40.0 7.39 1.30 × 104
50.0 9.23 1.63 × 104
60.0 11.1 1.95 × 104
70.0 12.9 2.28 × 104
80.0 14.8 2.60 × 104
90.0 16.6 2.93 × 104
95.8 17.7 3.12 × 104
Steel I Beam: W18 × 35 (Wide Flange 18 inch tall × 35 lbf/ft)
L = 150 ft
P (lbf/ft) w_max (in) stress_max (psi)
35.0 13.4 1.64 × 104
40.0 15.3 1.87 × 104
46.2 17.7 2.17 × 104
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