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Glossary » Beams » Simply Supported » Uniformly Distributed Load » Two 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 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 = 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 1.81 × 10-6 9.18
80.0 2.07 × 10-6 10.5
90.0 2.33 × 10-6 11.8
100 2.58 × 10-6 13.1
200 5.17 × 10-6 26.2
300 7.75 × 10-6 39.4
400 1.03 × 10-5 52.5
500 1.29 × 10-5 65.6
600 1.55 × 10-5 78.7
700 1.81 × 10-5 91.8
800 2.07 × 10-5 105
900 2.33 × 10-5 118
1000 2.58 × 10-5 131
2000 5.17 × 10-5 262
3000 7.75 × 10-5 394
4000 1.03 × 10-4 525
5000 1.29 × 10-4 656
6000 1.55 × 10-4 787
7000 1.81 × 10-4 918
8000 2.07 × 10-4 1050
9000 2.33 × 10-4 1180
1.00 × 104 2.58 × 10-4 1310
2.00 × 104 5.17 × 10-4 2620
3.00 × 104 7.75 × 10-4 3940
4.00 × 104 0.00103 5250
5.00 × 104 0.00129 6560
6.00 × 104 0.00155 7870
7.00 × 104 0.00181 9180
8.00 × 104 0.00207 1.05 × 104
9.00 × 104 0.00233 1.18 × 104
1.00 × 105 0.00258 1.31 × 104
2.00 × 105 0.00517 2.62 × 104
3.00 × 105 0.00775 3.94 × 104
4.00 × 105 0.0103 5.25 × 104
5.00 × 105 0.0129 6.56 × 104
6.00 × 105 0.0155 7.87 × 104
7.00 × 105 0.0181 9.18 × 104
8.00 × 105 0.0207 1.05 × 105
9.00 × 105 0.0233 1.18 × 105
1.00 × 106 0.0258 1.31 × 105
2.00 × 106 0.0517 2.62 × 105
2.26 × 106 0.0585 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 1.40 × 10-5 25.5
80.0 1.60 × 10-5 29.2
90.0 1.79 × 10-5 32.8
100 1.99 × 10-5 36.4
200 3.99 × 10-5 72.9
300 5.98 × 10-5 109
400 7.98 × 10-5 146
500 9.97 × 10-5 182
600 1.20 × 10-4 219
700 1.40 × 10-4 255
800 1.60 × 10-4 292
900 1.79 × 10-4 328
1000 1.99 × 10-4 364
2000 3.99 × 10-4 729
3000 5.98 × 10-4 1090
4000 7.98 × 10-4 1460
5000 9.97 × 10-4 1820
6000 0.00120 2190
7000 0.00140 2550
8000 0.00160 2920
9000 0.00179 3280
1.00 × 104 0.00199 3640
2.00 × 104 0.00399 7290
3.00 × 104 0.00598 1.09 × 104
4.00 × 104 0.00798 1.46 × 104
5.00 × 104 0.00997 1.82 × 104
6.00 × 104 0.0120 2.19 × 104
7.00 × 104 0.0140 2.55 × 104
8.00 × 104 0.0160 2.92 × 104
9.00 × 104 0.0179 3.28 × 104
1.00 × 105 0.0199 3.64 × 104
2.00 × 105 0.0399 7.29 × 104
3.00 × 105 0.0598 1.09 × 105
4.00 × 105 0.0798 1.46 × 105
5.00 × 105 0.0997 1.82 × 105
6.00 × 105 0.120 2.19 × 105
7.00 × 105 0.140 2.55 × 105
8.00 × 105 0.160 2.92 × 105
8.15 × 105 0.163 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 2.23 × 10-4 102
80.0 2.55 × 10-4 117
90.0 2.87 × 10-4 131
100 3.19 × 10-4 146
200 6.38 × 10-4 292
300 9.57 × 10-4 437
400 0.00128 583
500 0.00160 729
600 0.00191 875
700 0.00223 1020
800 0.00255 1170
900 0.00287 1310
1000 0.00319 1460
2000 0.00638 2920
3000 0.00957 4370
4000 0.0128 5830
5000 0.0160 7290
6000 0.0191 8750
7000 0.0223 1.02 × 104
8000 0.0255 1.17 × 104
9000 0.0287 1.31 × 104
1.00 × 104 0.0319 1.46 × 104
2.00 × 104 0.0638 2.92 × 104
3.00 × 104 0.0957 4.37 × 104
4.00 × 104 0.128 5.83 × 104
5.00 × 104 0.160 7.29 × 104
6.00 × 104 0.191 8.75 × 104
7.00 × 104 0.223 1.02 × 105
8.00 × 104 0.255 1.17 × 105
9.00 × 104 0.287 1.31 × 105
1.00 × 105 0.319 1.46 × 105
2.00 × 105 0.638 2.92 × 105
2.04 × 105 0.650 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 0.00113 230
80.0 0.00129 262
90.0 0.00145 295
100 0.00162 328
200 0.00323 656
300 0.00485 984
400 0.00646 1310
500 0.00808 1640
600 0.00969 1970
700 0.0113 2300
800 0.0129 2620
900 0.0145 2950
1000 0.0162 3280
2000 0.0323 6560
3000 0.0485 9840
4000 0.0646 1.31 × 104
5000 0.0808 1.64 × 104
6000 0.0969 1.97 × 104
7000 0.113 2.30 × 104
8000 0.129 2.62 × 104
9000 0.145 2.95 × 104
1.00 × 104 0.162 3.28 × 104
2.00 × 104 0.323 6.56 × 104
3.00 × 104 0.485 9.84 × 104
4.00 × 104 0.646 1.31 × 105
5.00 × 104 0.808 1.64 × 105
6.00 × 104 0.969 1.97 × 105
7.00 × 104 1.13 2.30 × 105
8.00 × 104 1.29 2.62 × 105
9.00 × 104 1.45 2.95 × 105
9.06 × 104 1.46 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 0.00357 408
80.0 0.00408 467
90.0 0.00460 525
100 0.00511 583
200 0.0102 1170
300 0.0153 1750
400 0.0204 2330
500 0.0255 2920
600 0.0306 3500
700 0.0357 4080
800 0.0408 4670
900 0.0460 5250
1000 0.0511 5830
2000 0.102 1.17 × 104
3000 0.153 1.75 × 104
4000 0.204 2.33 × 104
5000 0.255 2.92 × 104
6000 0.306 3.50 × 104
7000 0.357 4.08 × 104
8000 0.408 4.67 × 104
9000 0.460 5.25 × 104
1.00 × 104 0.511 5.83 × 104
2.00 × 104 1.02 1.17 × 105
3.00 × 104 1.53 1.75 × 105
4.00 × 104 2.04 2.33 × 105
5.00 × 104 2.55 2.92 × 105
5.09 × 104 2.60 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 0.00873 638
80.0 0.00997 729
90.0 0.0112 820
100 0.0125 911
200 0.0249 1820
300 0.0374 2730
400 0.0499 3640
500 0.0623 4560
600 0.0748 5470
700 0.0873 6380
800 0.0997 7290
900 0.112 8200
1000 0.125 9110
2000 0.249 1.82 × 104
3000 0.374 2.73 × 104
4000 0.499 3.64 × 104
5000 0.623 4.56 × 104
6000 0.748 5.47 × 104
7000 0.873 6.38 × 104
8000 0.997 7.29 × 104
9000 1.12 8.20 × 104
1.00 × 104 1.25 9.11 × 104
2.00 × 104 2.49 1.82 × 105
3.00 × 104 3.74 2.73 × 105
3.26 × 104 4.06 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 0.0181 918
80.0 0.0207 1050
90.0 0.0233 1180
100 0.0258 1310
200 0.0517 2620
300 0.0775 3940
400 0.103 5250
500 0.129 6560
600 0.155 7870
700 0.181 9180
800 0.207 1.05 × 104
900 0.233 1.18 × 104
1000 0.258 1.31 × 104
2000 0.517 2.62 × 104
3000 0.775 3.94 × 104
4000 1.03 5.25 × 104
5000 1.29 6.56 × 104
6000 1.55 7.87 × 104
7000 1.81 9.18 × 104
8000 2.07 1.05 × 105
9000 2.33 1.18 × 105
1.00 × 104 2.58 1.31 × 105
2.00 × 104 5.17 2.62 × 105
2.26 × 104 5.85 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 0.0572 1630
80.0 0.0654 1870
90.0 0.0735 2100
100 0.0817 2330
200 0.163 4670
300 0.245 7000
400 0.327 9330
500 0.408 1.17 × 104
600 0.490 1.40 × 104
700 0.572 1.63 × 104
800 0.654 1.87 × 104
900 0.735 2.10 × 104
1000 0.817 2.33 × 104
2000 1.63 4.67 × 104
3000 2.45 7.00 × 104
4000 3.27 9.33 × 104
5000 4.08 1.17 × 105
6000 4.90 1.40 × 105
7000 5.72 1.63 × 105
8000 6.54 1.87 × 105
9000 7.35 2.10 × 105
1.00 × 104 8.17 2.33 × 105
1.27 × 104 10.4 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 0.140 2550
80.0 0.160 2920
90.0 0.179 3280
100 0.199 3640
200 0.399 7290
300 0.598 1.09 × 104
400 0.798 1.46 × 104
500 0.997 1.82 × 104
600 1.20 2.19 × 104
700 1.40 2.55 × 104
800 1.60 2.92 × 104
900 1.79 3.28 × 104
1000 1.99 3.64 × 104
2000 3.99 7.29 × 104
3000 5.98 1.09 × 105
4000 7.98 1.46 × 105
5000 9.97 1.82 × 105
6000 12.0 2.19 × 105
7000 14.0 2.55 × 105
8000 16.0 2.92 × 105
8150 16.3 2.97 × 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 0.289 3670
80.0 0.331 4200
90.0 0.372 4720
100 0.414 5250
200 0.827 1.05 × 104
300 1.24 1.57 × 104
400 1.65 2.10 × 104
500 2.07 2.62 × 104
600 2.48 3.15 × 104
700 2.89 3.67 × 104
800 3.31 4.20 × 104
900 3.72 4.72 × 104
1000 4.14 5.25 × 104
2000 8.27 1.05 × 105
3000 12.4 1.57 × 105
4000 16.5 2.10 × 105
4350 18.0 2.28 × 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 0.536 5000
80.0 0.613 5710
90.0 0.690 6430
100 0.766 7140
200 1.53 1.43 × 104
300 2.30 2.14 × 104
400 3.06 2.86 × 104
500 3.83 3.57 × 104
600 4.60 4.29 × 104
700 5.36 5.00 × 104
800 6.13 5.71 × 104
900 6.90 6.43 × 104
1000 7.66 7.14 × 104
2000 15.3 1.43 × 105
2350 18.0 1.68 × 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 0.915 6530
80.0 1.05 7460
90.0 1.18 8400
100 1.31 9330
200 2.61 1.87 × 104
300 3.92 2.80 × 104
400 5.23 3.73 × 104
500 6.54 4.67 × 104
600 7.84 5.60 × 104
700 9.15 6.53 × 104
800 10.5 7.46 × 104
900 11.8 8.40 × 104
1000 13.1 9.33 × 104
1380 18.0 1.28 × 105
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 1.47 8270
80.0 1.67 9450
90.0 1.88 1.06 × 104
100 2.09 1.18 × 104
200 4.19 2.36 × 104
300 6.28 3.54 × 104
400 8.37 4.72 × 104
500 10.5 5.90 × 104
600 12.6 7.09 × 104
700 14.7 8.27 × 104
800 16.7 9.45 × 104
860 18.0 1.02 × 105
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 2.23 1.02 × 104
80.0 2.55 1.17 × 104
90.0 2.87 1.31 × 104
100 3.19 1.46 × 104
200 6.38 2.92 × 104
300 9.57 4.37 × 104
400 12.8 5.83 × 104
500 16.0 7.29 × 104
564 18.0 8.22 × 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 5.45 1.59 × 104
80.0 6.23 1.82 × 104
90.0 7.01 2.05 × 104
100 7.79 2.28 × 104
200 15.6 4.56 × 104
231 18.0 5.26 × 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 11.3 2.30 × 104
80.0 12.9 2.62 × 104
90.0 14.5 2.95 × 104
100 16.2 3.28 × 104
111 18.0 3.65 × 104
Additional Information
Related Pages
FREE Publications
Metal 3D Printing Design Guide

Direct Metal Laser Sintering (DMLS) 3D printing for parts with reduced cost and little waste.

3D Scanners

A white paper to assist in the evaluation of 3D scanning hardware solutions.

Injection Molding Design Guide

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

Negotiate Your Salary

Learn the best principles to negotiate the salary you deserve!

more publications