Advantages and Disadvantages of Steel

Steel structures are significantly lighter than other materials.

Steel's properties remain consistent regardless of the steel material used.

Steel follows Hooke's Law, meaning its deformation is precisely predictable.

Steel can bend significantly before failing.

Steel combines strength with the ability to bend significantly before failure.

Steel structures can have additional parts (e.g., wings, bays, bridge widenings).

Steel, despite its advantages, has some drawbacks that make other materials like concrete suitable for certain applications.

Steel's high strength results in a lower weight structure.

Steel can lose its ductility and break unexpectedly under stress (especially at stress concentrations), triggered by fatigue or cold temperatures.

Cast iron, primarily from 1777-1820, was a pioneering structural material, used first in arch spans, and later in bridges.

Wrought iron gradually replaced cast iron in the 1840s as a structural material, offering advantages.

The Bessemer process (1855) enabled large-scale and cheaper steel production.

Steel can be rolled into various shapes (I, T, C) that maximize structural strength for their weight.

Structural steel shapes like I-beams, T-beams, and C-channels are economically produced and retain their structural properties after rolling.

Producing steel shapes from 1989 with yield strengths ranging from 24,000 to 100,000 psi.

A measure of a shape's resistance to bending.

Different shapes of steel used in structures, like angles, tees, zees, plates, I-shapes (S and W beams).

Steel shapes made by rolling the metal, commonly used shapes include I-shapes.

Steel shapes with a flange and web, like wide-flange (W) beams and American standard (S) beams.

A standardized way to name steel shapes, using abbreviations (e.g., W, S, HP, C, MC).

A wide-flange steel section, identified by a "W" in its designation.

An American standard steel section, identified by an "S" in its designation.

A specific W-shaped steel section approximately 27 inches deep and weighing 114 lbs per foot.

A specific S-shaped steel section, 12 inches deep and weighing 35 pounds per foot.

Steel containing significant amounts of elements like silicon, nickel, manganese, and copper, which modifies its properties.

The relationship between the applied stress on a material and its resulting deformation (strain).

The range of stress where a material returns to its original shape after the load is removed.

The stress at which a material begins to deform permanently.

A test that measures a material's strength and ductility by applying a pulling force.

A simplified representation of the relationship between stress and strain, neglecting minor variations.

A structural shape with two legs of equal length, forming a right angle.

An equal leg angle with each leg 6 inches long and ½ inch thick.

Steel structures are lighter than comparable structures built with other materials, leading to cost savings in shipping, erection, and foundation.

The use of shallow beams made possible by steel's strength allows for reduced floor depths in buildings, optimizing space and reducing construction costs.

Steel structures often require less fireproofing material due to its strength, leading to potential cost savings.

Structural engineers ensure buildings stand strong against loads and avoid excessive deflections or vibrations that could cause harm or damage.

Structural engineers optimize designs for cost-effectiveness, considering factors like standard-sized members and simple connections.

Engineers understand fabrication methods and adapt designs to the available facilities, ensuring a smooth construction process.

Engineers need to be familiar with industry practices, tolerances, and clearances to ensure practical and economical designs.

Engineers aim for designs that are feasible to build by considering fabrication methods and limitations.

Computers are vital for efficient structural steel analysis and design, handling complex calculations that would be time-consuming manually.

Commercial software packages can perform both structural analysis (calculating forces) and design (choosing appropriate steel sections) for steel structures.

While computers boost productivity, they may limit a young engineer's intuition and understanding of structural behavior through direct experience.

Effective computer use in steel design still relies on solid understanding of engineering principles. It's like needing to know how a car works to fix it.

Computers are powerful tools, but they can't replace fundamental engineering understanding. They are useless without knowing how structures work.

While design software is helpful, inexperienced engineers need to develop a 'feel' for structural behavior through practical experience to understand how structures work.