Steel design

Key takeaways

Steel design belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Steel design to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Steel design from memory before moving on to harder problems.

Reference excerpt

Steel Design, or more specifically, Structural Steel Design, is an area of structural engineering used to design steel structures. These structures include schools, houses, bridges, commercial centers, tall buildings, warehouses, aircraft, ships and stadiums. The design and use of steel frames are commonly employed in the design of steel structures. More advanced structures include steel plates and shells. In structural engineering, a structure is a body or combination of pieces of the rigid bodies in space that form a fitness system for supporting loads and resisting moments. The effects of loads and moments on structures are determined through structural analysis. A steel structure is composed of structural members that are made of steel, usually with standard cross-sectional profiles and standards of chemical composition and mechanical properties. The depth of steel beams used in the construction of bridges is usually governed by the maximum moment, and the cross-section is then verified for shear strength near supports and lateral torsional buckling (by determining the distance between transverse members connecting adjacent beams). Steel column members must be verified as adequate to prevent buckling after axial and moment requirements are met. There are currently two common methods of steel design: The first method is the Allowable Strength Design (ASD) method. The second is the Load and Resistance Factor Design (LRFD) method. Both use a strength, or ultimate level design approach.

Load combination equations

Allowable Strength Design For ASD, the required strength, Ra, is determined from the following load combinations (according to the AISC SCM, 13 ed.) and: D + F D + H + F + L + T D + H + F + (Lr or S or R) D + H + F + 0.75(L + T) + 0.75(Lr or S or R) D + H + F ± (0.6W or 0.7E) D + H + F + (0.75W or 0.7E) + 0.75L + 0.75(Lr or S or R) 0.6D + 0.6W 0.6D ± 0.7E where:

D = dead load, Di = weight of Ice, E = earthquake load, F = load due to fluids with well-defined pressures and maximum heights, Fa = flood load, H = load due to lateral earth pressure, ground water pressure, or pressure of bulk materials, L = live load due to occupancy, Lr = roof live load, S = snow load, R = nominal load due to initial rainwater or ice, exclusive of the ponding contribution, T = self straining load, W = wind load, Wi = wind on ice.. Special Provisions exist for accounting flood loads and atmospheric loads i.e. Di and Wi Note that Allowable Strength Design is NOT equivalent to Allowable Stress Design, as governed by AISC 9th Edition. Allowable Strength Design still uses a strength, or ultimate level, design approach.

Load and Resistance Factor Design For LRFD, the required strength, Ru, is determined from the following factored load combinations: 1.4(D + F) 1.2(D + F + T) + 1.6(L + H) + 0.5(Lr or S or R) 1.2D + 1.6(Lr or S or R) + (L or 0.8W) 1.2D + 1.0W + L + 0.5(Lr or S or R) 1.2D ± 1.0E + L + 0.2S + 0.9D + 1.6W + 1.6H 0.9D + 1.6 H ± (1.6W or 1.0E) where the letters for the loads are the same as for ASD.

AISC Steel Construction Manual The American Institute of Steel Construction (AISC), Inc. publishes the Steel Construction Manual (Steel construction manual, or SCM), which is currently in its 16th edition. Structural engineers use this manual in analyzing, and designing various steel structures. Some of the chapters of the book are as follows.

Dimensions and properties of various types of steel sections available on the market (W, S, C, WT, HSS, etc.) General Design Considerations Design of Flexural Members Design of Compression Members Design of Tension members Design of Members Subject to Combined Loading Design Consideration for Bolts Design Considerations for Welds Design of Connecting Elements Design of Simple Shear Connections Design of Flexure Moment Connections Design of Fully Restrained (FR) Moment Connections Design of Bracing Connections and Truss Connections Design of Beam Bearing Plates, Column Base Plates, Anchor Rods, and Column Splices Design of Hanger Connections, Bracket Plates, and Crane-Rail Connections General Nomenclature Specification and Commentary for Structural Steel Buildings RCSC Specification and Commentary for Structural Joints Using High-Strength Bolts Code of Standard Practice and Commentary for Structural Steel Buildings and Bridges Miscellaneous Data and Mathematical Information

CISC Handbook of Steel Construction Canadian Institute of Steel Construction publishes the "CISC Handbook of steel Construction". CISC is a national industry organization representing the structural steel, open-web steel joist and steel plate fabrication industries in Canada. It serves the same purpose as the AISC manual, but conforms with Canadian standards.

Worked examples

Example 1 — a first encounter with Steel design

Start with the simplest possible case. Write down what Steel design claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Steel design before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Steel design ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Steel design

In research: Steel design appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Steel design in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Steel design is common in secondary-school and first-year university syllabi. It links to neighbouring topics Structural engineering, Structural steel, so understanding it makes those chapters shorter.
In everyday life: Look for Steel design outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Steel design in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Steel design means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Steel design out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Steel design in simple terms?

Steel Design, or more specifically, Structural Steel Design, is an area of structural engineering used to design steel structures. These structures include schools, houses, bridges, commercial centers, tall buildings, warehouses, aircraft, ships and stadiums.

Why does Steel design matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Steel design?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Steel design.