Young's Modulus of Structural Steel
| Value | 2e11 Pa |
| Status | Measured: ± 3,000,000,000 Pa (0.015 relative) |
| Source | AISC Steel Construction Manual, 15th ed. |
| Categories | Material PropertiesEngineering & Trade |
| microbar | 2,000,000,000,000 μbar |
| barye | 2,000,000,000,000 Ba |
| millitorr | 1,500,123,400,000 mTorr |
| pascal | 200,000,000,000 Pa |
| millimeter of water column | 20,394,324,000 mmH₂O |
| pound per square foot | 4,177,086,800 lb/ft² |
| centimeter of water column | 2,039,432,400 cmH₂O |
| hectopascal | 2,000,000,000 hPa |
| millibar | 2,000,000,000 mbar |
| torr | 1,500,123,400 Torr |
| millimeter of mercury | 1,500,123,200 mmHg |
| inch of water column | 802,926,160 in w.g. |
| kilopascal | 200,000,000 kPa |
| foot of water column | 66,910,513 ft H₂O |
| inch of mercury | 59,059,967 inHg |
| pound per square inch | 29,007,548 psi |
| meter of water column | 20,394,324 m H₂O |
| decibar | 20,000,000 dbar |
| kilogram-force per square centimeter | 2,039,432.4 kgf/cm² |
| bar | 2,000,000 bar |
| atmosphere | 1,973,846.5 atm |
| megapascal | 200,000 MPa |
| kip per square inch | 29,007.548 ksi |
| gigapascal | 200 GPa |
| million pounds per square inch | 29.007548 Mpsi |
Learning zone
Stiffness and strength come from different physics, and steel is the cleanest demonstration. Young's modulus measures the stiffness of the iron-iron atomic bond, so it is the same 200 GPa for A36, A992, A572 Grade 65 and a quenched-and-tempered alloy — heat treatment and alloying rearrange dislocations and grain structure, which governs where the material yields, but they barely touch interatomic spacing. Yield strength varies by a factor of five across those grades; E varies by about 2 %. AISC prints one number, 29 000 ksi, and uses it for every steel in the manual.
The practical consequence is that a stronger steel does not give a stiffer beam. Deflection under service load depends on E and I only, so switching a floor beam from A36 to A992 buys strength and buys nothing at all in deflection — if the beam is deflection-governed, and long-span floor beams usually are, the only fix is more depth or more moment of inertia. The value falls with temperature (about 10 % by 300 °C, and roughly half by 600 °C), which is why fire design uses reduced-modulus curves rather than this figure.