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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Two Equal Spans » Wide Flange Steel I Beam » W8 × 18
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 = 61.9 in4) for the W8 × 18 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
   
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 6.96 × 10-6 16.0
20.0 7.73 × 10-6 17.8
30.0 1.16 × 10-5 26.6
40.0 1.55 × 10-5 35.5
50.0 1.93 × 10-5 44.4
60.0 2.32 × 10-5 53.3
70.0 2.71 × 10-5 62.1
80.0 3.09 × 10-5 71.0
90.0 3.48 × 10-5 79.9
100 3.87 × 10-5 88.8
200 7.73 × 10-5 178
300 1.16 × 10-4 266
400 1.55 × 10-4 355
500 1.93 × 10-4 444
600 2.32 × 10-4 533
700 2.71 × 10-4 621
800 3.09 × 10-4 710
900 3.48 × 10-4 799
1000 3.87 × 10-4 888
2000 7.73 × 10-4 1780
3000 0.00116 2660
4000 0.00155 3550
5000 0.00193 4440
6000 0.00232 5330
7000 0.00271 6210
8000 0.00309 7100
9000 0.00348 7990
1.00 × 104 0.00387 8880
2.00 × 104 0.00773 1.78 × 104
3.00 × 104 0.0116 2.66 × 104
4.00 × 104 0.0155 3.55 × 104
5.00 × 104 0.0193 4.44 × 104
6.00 × 104 0.0232 5.33 × 104
7.00 × 104 0.0271 6.21 × 104
8.00 × 104 0.0309 7.10 × 104
9.00 × 104 0.0348 7.99 × 104
1.00 × 105 0.0387 8.88 × 104
2.00 × 105 0.0773 1.78 × 105
3.00 × 105 0.116 2.66 × 105
3.35 × 105 0.129 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 5.37 × 10-5 44.4
20.0 5.97 × 10-5 49.3
30.0 8.95 × 10-5 74.0
40.0 1.19 × 10-4 98.6
50.0 1.49 × 10-4 123
60.0 1.79 × 10-4 148
70.0 2.09 × 10-4 173
80.0 2.39 × 10-4 197
90.0 2.69 × 10-4 222
100 2.98 × 10-4 247
200 5.97 × 10-4 493
300 8.95 × 10-4 740
400 0.00119 986
500 0.00149 1230
600 0.00179 1480
700 0.00209 1730
800 0.00239 1970
900 0.00269 2220
1000 0.00298 2470
2000 0.00597 4930
3000 0.00895 7400
4000 0.0119 9860
5000 0.0149 1.23 × 104
6000 0.0179 1.48 × 104
7000 0.0209 1.73 × 104
8000 0.0239 1.97 × 104
9000 0.0269 2.22 × 104
1.00 × 104 0.0298 2.47 × 104
2.00 × 104 0.0597 4.93 × 104
3.00 × 104 0.0895 7.40 × 104
4.00 × 104 0.119 9.86 × 104
5.00 × 104 0.149 1.23 × 105
6.00 × 104 0.179 1.48 × 105
7.00 × 104 0.209 1.73 × 105
8.00 × 104 0.239 1.97 × 105
9.00 × 104 0.269 2.22 × 105
1.00 × 105 0.298 2.47 × 105
1.20 × 105 0.359 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 8.59 × 10-4 178
20.0 9.55 × 10-4 197
30.0 0.00143 296
40.0 0.00191 395
50.0 0.00239 493
60.0 0.00286 592
70.0 0.00334 690
80.0 0.00382 789
90.0 0.00430 888
100 0.00477 986
200 0.00955 1970
300 0.0143 2960
400 0.0191 3950
500 0.0239 4930
600 0.0286 5920
700 0.0334 6900
800 0.0382 7890
900 0.0430 8880
1000 0.0477 9860
2000 0.0955 1.97 × 104
3000 0.143 2.96 × 104
4000 0.191 3.95 × 104
5000 0.239 4.93 × 104
6000 0.286 5.92 × 104
7000 0.334 6.90 × 104
8000 0.382 7.89 × 104
9000 0.430 8.88 × 104
1.00 × 104 0.477 9.86 × 104
2.00 × 104 0.955 1.97 × 105
3.00 × 104 1.43 2.96 × 105
3.01 × 104 1.44 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.00435 399
20.0 0.00483 444
30.0 0.00725 666
40.0 0.00967 888
50.0 0.0121 1110
60.0 0.0145 1330
70.0 0.0169 1550
80.0 0.0193 1780
90.0 0.0217 2000
100 0.0242 2220
200 0.0483 4440
300 0.0725 6660
400 0.0967 8880
500 0.121 1.11 × 104
600 0.145 1.33 × 104
700 0.169 1.55 × 104
800 0.193 1.78 × 104
900 0.217 2.00 × 104
1000 0.242 2.22 × 104
2000 0.483 4.44 × 104
3000 0.725 6.66 × 104
4000 0.967 8.88 × 104
5000 1.21 1.11 × 105
6000 1.45 1.33 × 105
7000 1.69 1.55 × 105
8000 1.93 1.78 × 105
9000 2.17 2.00 × 105
1.00 × 104 2.42 2.22 × 105
1.34 × 104 3.23 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.0137 710
20.0 0.0153 789
30.0 0.0229 1180
40.0 0.0306 1580
50.0 0.0382 1970
60.0 0.0458 2370
70.0 0.0535 2760
80.0 0.0611 3160
90.0 0.0687 3550
100 0.0764 3950
200 0.153 7890
300 0.229 1.18 × 104
400 0.306 1.58 × 104
500 0.382 1.97 × 104
600 0.458 2.37 × 104
700 0.535 2.76 × 104
800 0.611 3.16 × 104
900 0.687 3.55 × 104
1000 0.764 3.95 × 104
2000 1.53 7.89 × 104
3000 2.29 1.18 × 105
4000 3.06 1.58 × 105
5000 3.82 1.97 × 105
6000 4.58 2.37 × 105
7000 5.35 2.76 × 105
7530 5.75 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.0336 1110
20.0 0.0373 1230
30.0 0.0559 1850
40.0 0.0746 2470
50.0 0.0932 3080
60.0 0.112 3700
70.0 0.131 4310
80.0 0.149 4930
90.0 0.168 5550
100 0.186 6160
200 0.373 1.23 × 104
300 0.559 1.85 × 104
400 0.746 2.47 × 104
500 0.932 3.08 × 104
600 1.12 3.70 × 104
700 1.31 4.31 × 104
800 1.49 4.93 × 104
900 1.68 5.55 × 104
1000 1.86 6.16 × 104
2000 3.73 1.23 × 105
3000 5.59 1.85 × 105
4000 7.46 2.47 × 105
4820 8.99 2.97 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.0696 1600
20.0 0.0773 1780
30.0 0.116 2660
40.0 0.155 3550
50.0 0.193 4440
60.0 0.232 5330
70.0 0.271 6210
80.0 0.309 7100
90.0 0.348 7990
100 0.387 8880
200 0.773 1.78 × 104
300 1.16 2.66 × 104
400 1.55 3.55 × 104
500 1.93 4.44 × 104
600 2.32 5.33 × 104
700 2.71 6.21 × 104
800 3.09 7.10 × 104
900 3.48 7.99 × 104
1000 3.87 8.88 × 104
2000 7.73 1.78 × 105
2110 8.14 1.87 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.220 2840
20.0 0.244 3160
30.0 0.367 4730
40.0 0.489 6310
50.0 0.611 7890
60.0 0.733 9470
70.0 0.855 1.10 × 104
80.0 0.978 1.26 × 104
90.0 1.10 1.42 × 104
100 1.22 1.58 × 104
200 2.44 3.16 × 104
300 3.67 4.73 × 104
400 4.89 6.31 × 104
500 6.11 7.89 × 104
600 7.33 9.47 × 104
666 8.14 1.05 × 105
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 0.537 4440
20.0 0.597 4930
30.0 0.895 7400
40.0 1.19 9860
50.0 1.49 1.23 × 104
60.0 1.79 1.48 × 104
70.0 2.09 1.73 × 104
80.0 2.39 1.97 × 104
90.0 2.69 2.22 × 104
100 2.98 2.47 × 104
200 5.97 4.93 × 104
273 8.14 6.73 × 104
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 1.11 6390
20.0 1.24 7100
30.0 1.86 1.07 × 104
40.0 2.47 1.42 × 104
50.0 3.09 1.78 × 104
60.0 3.71 2.13 × 104
70.0 4.33 2.49 × 104
80.0 4.95 2.84 × 104
90.0 5.57 3.20 × 104
100 6.19 3.55 × 104
132 8.14 4.67 × 104
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 2.06 8700
20.0 2.29 9670
30.0 3.44 1.45 × 104
40.0 4.58 1.93 × 104
50.0 5.73 2.42 × 104
60.0 6.88 2.90 × 104
70.0 8.02 3.38 × 104
71.0 8.14 3.43 × 104
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 3.52 1.14 × 104
20.0 3.91 1.26 × 104
30.0 5.87 1.89 × 104
40.0 7.82 2.52 × 104
41.6 8.14 2.63 × 104
Steel I Beam: W8 × 18 (Wide Flange 8 inch tall × 18 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
18.0 5.64 1.44 × 104
20.0 6.26 1.60 × 104
26.0 8.14 2.08 × 104
Additional Information
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