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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Four Equal Spans » S Section Steel I Beam » S18 × 70
S Section Steel I Beam | Single Span | Two Equal Spans | Three Equal Spans | Four Equal Spans

For a simply supported beam in four equal spans, we compute the displacement at the middle of the first and fourth spans, and the maximum normal stress stress_max occuring at the second and fourth supports of the beam.
The tabulated data listed in this page are calculated based on the area moment of inertia (Ixx = 926 in4) for the S18 × 70 S Section 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: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 3.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 2.19 × 10-6 7.87
80.0 2.50 × 10-6 8.99
90.0 2.81 × 10-6 10.1
100 3.13 × 10-6 11.2
200 6.25 × 10-6 22.5
300 9.38 × 10-6 33.7
400 1.25 × 10-5 45.0
500 1.56 × 10-5 56.2
600 1.88 × 10-5 67.5
700 2.19 × 10-5 78.7
800 2.50 × 10-5 89.9
900 2.81 × 10-5 101
1000 3.13 × 10-5 112
2000 6.25 × 10-5 225
3000 9.38 × 10-5 337
4000 1.25 × 10-4 450
5000 1.56 × 10-4 562
6000 1.88 × 10-4 675
7000 2.19 × 10-4 787
8000 2.50 × 10-4 899
9000 2.81 × 10-4 1010
1.00 × 104 3.13 × 10-4 1120
2.00 × 104 6.25 × 10-4 2250
3.00 × 104 9.38 × 10-4 3370
4.00 × 104 0.00125 4500
5.00 × 104 0.00156 5620
6.00 × 104 0.00188 6750
7.00 × 104 0.00219 7870
8.00 × 104 0.00250 8990
9.00 × 104 0.00281 1.01 × 104
1.00 × 105 0.00313 1.12 × 104
2.00 × 105 0.00625 2.25 × 104
3.00 × 105 0.00938 3.37 × 104
4.00 × 105 0.0125 4.50 × 104
5.00 × 105 0.0156 5.62 × 104
6.00 × 105 0.0188 6.75 × 104
7.00 × 105 0.0219 7.87 × 104
8.00 × 105 0.0250 8.99 × 104
9.00 × 105 0.0281 1.01 × 105
1.00 × 106 0.0313 1.12 × 105
2.00 × 106 0.0625 2.25 × 105
2.64 × 106 0.0826 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 5.00 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 1.69 × 10-5 21.9
80.0 1.93 × 10-5 25.0
90.0 2.17 × 10-5 28.1
100 2.41 × 10-5 31.2
200 4.82 × 10-5 62.5
300 7.24 × 10-5 93.7
400 9.65 × 10-5 125
500 1.21 × 10-4 156
600 1.45 × 10-4 187
700 1.69 × 10-4 219
800 1.93 × 10-4 250
900 2.17 × 10-4 281
1000 2.41 × 10-4 312
2000 4.82 × 10-4 625
3000 7.24 × 10-4 937
4000 9.65 × 10-4 1250
5000 0.00121 1560
6000 0.00145 1870
7000 0.00169 2190
8000 0.00193 2500
9000 0.00217 2810
1.00 × 104 0.00241 3120
2.00 × 104 0.00482 6250
3.00 × 104 0.00724 9370
4.00 × 104 0.00965 1.25 × 104
5.00 × 104 0.0121 1.56 × 104
6.00 × 104 0.0145 1.87 × 104
7.00 × 104 0.0169 2.19 × 104
8.00 × 104 0.0193 2.50 × 104
9.00 × 104 0.0217 2.81 × 104
1.00 × 105 0.0241 3.12 × 104
2.00 × 105 0.0482 6.25 × 104
3.00 × 105 0.0724 9.37 × 104
4.00 × 105 0.0965 1.25 × 105
5.00 × 105 0.121 1.56 × 105
6.00 × 105 0.145 1.87 × 105
7.00 × 105 0.169 2.19 × 105
8.00 × 105 0.193 2.50 × 105
9.00 × 105 0.217 2.81 × 105
9.51 × 105 0.229 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 10.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 2.70 × 10-4 87.4
80.0 3.09 × 10-4 99.9
90.0 3.47 × 10-4 112
100 3.86 × 10-4 125
200 7.72 × 10-4 250
300 0.00116 375
400 0.00154 500
500 0.00193 625
600 0.00232 749
700 0.00270 874
800 0.00309 999
900 0.00347 1120
1000 0.00386 1250
2000 0.00772 2500
3000 0.0116 3750
4000 0.0154 5000
5000 0.0193 6250
6000 0.0232 7490
7000 0.0270 8740
8000 0.0309 9990
9000 0.0347 1.12 × 104
1.00 × 104 0.0386 1.25 × 104
2.00 × 104 0.0772 2.50 × 104
3.00 × 104 0.116 3.75 × 104
4.00 × 104 0.154 5.00 × 104
5.00 × 104 0.193 6.25 × 104
6.00 × 104 0.232 7.49 × 104
7.00 × 104 0.270 8.74 × 104
8.00 × 104 0.309 9.99 × 104
9.00 × 104 0.347 1.12 × 105
1.00 × 105 0.386 1.25 × 105
2.00 × 105 0.772 2.50 × 105
2.38 × 105 0.918 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 15.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.00137 197
80.0 0.00156 225
90.0 0.00176 253
100 0.00195 281
200 0.00391 562
300 0.00586 843
400 0.00782 1120
500 0.00977 1410
600 0.0117 1690
700 0.0137 1970
800 0.0156 2250
900 0.0176 2530
1000 0.0195 2810
2000 0.0391 5620
3000 0.0586 8430
4000 0.0782 1.12 × 104
5000 0.0977 1.41 × 104
6000 0.117 1.69 × 104
7000 0.137 1.97 × 104
8000 0.156 2.25 × 104
9000 0.176 2.53 × 104
1.00 × 104 0.195 2.81 × 104
2.00 × 104 0.391 5.62 × 104
3.00 × 104 0.586 8.43 × 104
4.00 × 104 0.782 1.12 × 105
5.00 × 104 0.977 1.41 × 105
6.00 × 104 1.17 1.69 × 105
7.00 × 104 1.37 1.97 × 105
8.00 × 104 1.56 2.25 × 105
9.00 × 104 1.76 2.53 × 105
1.00 × 105 1.95 2.81 × 105
1.06 × 105 2.07 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 20.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.00432 350
80.0 0.00494 400
90.0 0.00556 450
100 0.00618 500
200 0.0124 999
300 0.0185 1500
400 0.0247 2000
500 0.0309 2500
600 0.0371 3000
700 0.0432 3500
800 0.0494 4000
900 0.0556 4500
1000 0.0618 5000
2000 0.124 9990
3000 0.185 1.50 × 104
4000 0.247 2.00 × 104
5000 0.309 2.50 × 104
6000 0.371 3.00 × 104
7000 0.432 3.50 × 104
8000 0.494 4.00 × 104
9000 0.556 4.50 × 104
1.00 × 104 0.618 5.00 × 104
2.00 × 104 1.24 9.99 × 104
3.00 × 104 1.85 1.50 × 105
4.00 × 104 2.47 2.00 × 105
5.00 × 104 3.09 2.50 × 105
5.94 × 104 3.67 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 25.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.0106 546
80.0 0.0121 625
90.0 0.0136 703
100 0.0151 781
200 0.0302 1560
300 0.0452 2340
400 0.0603 3120
500 0.0754 3900
600 0.0905 4680
700 0.106 5460
800 0.121 6250
900 0.136 7030
1000 0.151 7810
2000 0.302 1.56 × 104
3000 0.452 2.34 × 104
4000 0.603 3.12 × 104
5000 0.754 3.90 × 104
6000 0.905 4.68 × 104
7000 1.06 5.46 × 104
8000 1.21 6.25 × 104
9000 1.36 7.03 × 104
1.00 × 104 1.51 7.81 × 104
2.00 × 104 3.02 1.56 × 105
3.00 × 104 4.52 2.34 × 105
3.80 × 104 5.74 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 30.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.0219 787
80.0 0.0250 899
90.0 0.0281 1010
100 0.0313 1120
200 0.0625 2250
300 0.0938 3370
400 0.125 4500
500 0.156 5620
600 0.188 6750
700 0.219 7870
800 0.250 8990
900 0.281 1.01 × 104
1000 0.313 1.12 × 104
2000 0.625 2.25 × 104
3000 0.938 3.37 × 104
4000 1.25 4.50 × 104
5000 1.56 5.62 × 104
6000 1.88 6.75 × 104
7000 2.19 7.87 × 104
8000 2.50 8.99 × 104
9000 2.81 1.01 × 105
1.00 × 104 3.13 1.12 × 105
2.00 × 104 6.25 2.25 × 105
2.64 × 104 8.26 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 40.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.0692 1400
80.0 0.0791 1600
90.0 0.0889 1800
100 0.0988 2000
200 0.198 4000
300 0.296 6000
400 0.395 7990
500 0.494 9990
600 0.593 1.20 × 104
700 0.692 1.40 × 104
800 0.791 1.60 × 104
900 0.889 1.80 × 104
1000 0.988 2.00 × 104
2000 1.98 4.00 × 104
3000 2.96 6.00 × 104
4000 3.95 7.99 × 104
5000 4.94 9.99 × 104
6000 5.93 1.20 × 105
7000 6.92 1.40 × 105
8000 7.91 1.60 × 105
9000 8.89 1.80 × 105
1.00 × 104 9.88 2.00 × 105
1.49 × 104 14.7 2.97 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 50.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.169 2190
80.0 0.193 2500
90.0 0.217 2810
100 0.241 3120
200 0.482 6250
300 0.724 9370
400 0.965 1.25 × 104
500 1.21 1.56 × 104
600 1.45 1.87 × 104
700 1.69 2.19 × 104
800 1.93 2.50 × 104
900 2.17 2.81 × 104
1000 2.41 3.12 × 104
2000 4.82 6.25 × 104
3000 7.24 9.37 × 104
4000 9.65 1.25 × 105
5000 12.1 1.56 × 105
6000 14.5 1.87 × 105
7000 16.9 2.19 × 105
7460 18.0 2.33 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 60.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.350 3150
80.0 0.400 3600
90.0 0.450 4050
100 0.500 4500
200 1.00 8990
300 1.50 1.35 × 104
400 2.00 1.80 × 104
500 2.50 2.25 × 104
600 3.00 2.70 × 104
700 3.50 3.15 × 104
800 4.00 3.60 × 104
900 4.50 4.05 × 104
1000 5.00 4.50 × 104
2000 10.0 8.99 × 104
3000 15.0 1.35 × 105
3600 18.0 1.62 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 70.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 0.649 4280
80.0 0.741 4900
90.0 0.834 5510
100 0.927 6120
200 1.85 1.22 × 104
300 2.78 1.84 × 104
400 3.71 2.45 × 104
500 4.63 3.06 × 104
600 5.56 3.67 × 104
700 6.49 4.28 × 104
800 7.41 4.90 × 104
900 8.34 5.51 × 104
1000 9.27 6.12 × 104
1940 18.0 1.19 × 105
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 80.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 1.11 5600
80.0 1.26 6400
90.0 1.42 7190
100 1.58 7990
200 3.16 1.60 × 104
300 4.74 2.40 × 104
400 6.32 3.20 × 104
500 7.91 4.00 × 104
600 9.49 4.80 × 104
700 11.1 5.60 × 104
800 12.6 6.40 × 104
900 14.2 7.19 × 104
1000 15.8 7.99 × 104
1140 18.0 9.10 × 104
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 90.0 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 1.77 7080
80.0 2.03 8090
90.0 2.28 9110
100 2.53 1.01 × 104
200 5.06 2.02 × 104
300 7.60 3.04 × 104
400 10.1 4.05 × 104
500 12.7 5.06 × 104
600 15.2 6.07 × 104
700 17.7 7.08 × 104
711 18.0 7.19 × 104
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 100 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 2.70 8740
80.0 3.09 9990
90.0 3.47 1.12 × 104
100 3.86 1.25 × 104
200 7.72 2.50 × 104
300 11.6 3.75 × 104
400 15.4 5.00 × 104
466 18.0 5.83 × 104
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 125 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 6.60 1.37 × 104
80.0 7.54 1.56 × 104
90.0 8.48 1.76 × 104
100 9.42 1.95 × 104
191 18.0 3.73 × 104
Steel I Beam: S18 × 70 (S18 inch tall × 70 lbf/ft)
L = 150 ft
P (lbf/ft) w_max (in) stress_max (psi)
70.0 13.7 1.97 × 104
80.0 15.6 2.25 × 104
90.0 17.6 2.53 × 104
92.1 18.0 2.59 × 104
Additional Information
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FREE Publications
Essentials of Manufacturing

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

STEM Career Outlook

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

Selecting the Right 3D Printer

Discover how to choose the right 3D printer for your needs and the key performance attributes to consider.

Injection Molding Design Guide

Guide for high quality and cost-effective plastic injection molding.

more publications