ARC5554-FALL2024_LECTURE-12_STEELBEAMDESIGN

Allowable Stress Design

A method of steel design where allowable stresses are limited to the elastic range.

Factor of Safety (F.S.)

A ratio defined as Ultimate strength divided by Maximum anticipated stress.

Bending Stress

Stress that beams are designed based on their maximum allowable stress.

Shear Stress

Force per unit area that needs to be checked in members for shear.

Deflection

The displacement of a beam under load, which must be checked against design limits.

Lateral Buckling

A beam deflection or sideways movement occurring due to insufficient rigidity in the lateral direction.

Compact Section

A beam section that satisfies specific AISC width-to-thickness ratio requirements.

Non-Compact Section

A beam section that does not meet the criteria for compact sections, affecting allowable bending stress.

Actual Bending Stress (𝒇𝒃)

Determined using the formula 𝒇𝒃 = 𝑴/𝑺, where 𝑴 is the maximum moment and S is the section modulus.

Actual Shear Stress (𝒇𝒗)

Calculated using the formula 𝒇𝒗 = 𝑽/(𝒅*𝒕𝒘), with 𝑽 as max shear force, d as beam depth, and 𝑡𝒘 as web thickness.

What is Allowable Stress Design?

A method of steel design limiting allowable stresses to the elastic range.

Define Factor of Safety (F.S.).

A ratio of Ultimate strength to Maximum anticipated stress.

What does bending stress refer to?

Stress that determines maximum allowable stress for beams.

Explain shear stress.

The force per unit area that needs checking in members for shear.

What is deflection in structural terms?

The displacement of a beam under load, checked against design limits.

What constitutes lateral buckling?

A beam's deflection or sideways movement due to insufficient lateral rigidity.

Define Compact Section in beams.

A section satisfying specific AISC width-to-thickness ratio requirements.

What is a Non-Compact Section?

A beam section that does not meet compact criteria, affecting allowable bending stress.

How is Actual Bending Stress (𝒇𝒃) calculated?

Using the formula 𝒇𝒃 = 𝑴/𝑺, where 𝑴 is maximum moment and S is section modulus.

How is Actual Shear Stress (𝒇𝒗) determined?

Calculated via 𝒇𝒗 = 𝑽/(𝒅*𝒕𝒘), with 𝑽 as max shear force, d as depth, and 𝑡𝒘 as web thickness.

What is structural engineering?

A branch of engineering focusing on the design and construction of structures to withstand loads.

Define load-bearing members.

Components of a structure that support and transfer loads to the ground.

What are static loads?

Loads that do not change over time, such as the weight of the structure itself.

Explain dynamic loads.

Loads subjected to a structure that vary with time, such as wind or earthquakes.

What is a moment in structural analysis?

A measure of the tendency of a force to rotate an object about an axis.

Define axial load.

A force applied along the longitudinal axis of a member.

What is bending moment?

The internal moment that induces bending in a beam or structural element.

Explain shear force.

A force that acts parallel to the section of a structural member.

What is a frame structure?

A structure made up of connected elements that support loads and prevent deformation.

Define truss system.

A stable structure made of triangular units, distributing loads through its members.

What is torsion?

The twisting of a structural element due to applied torque.

Explain axial deformation.

Change in length of a structural member due to axial loads.

What is a load path?

The route through which forces travel in a structure.

Define serviceability limit state.

Conditions under which a structure remains functional and meets user expectations.

What is structural stability?

The ability of a structure to maintain equilibrium and resist collapse.

Explain inflection point.

A point on a beam where the bending moment changes sign.

What is a footings role in construction?

Concrete bases that distribute building loads to the ground.

Define cantilever beam.

A beam fixed at one end and free to extend beyond its support.

What is the purpose of a foundation?

To transfer loads from the structure to the ground safely.

Explain the concept of load factor.

A multiplier applied to nominal loads for safety in design.

What is the purpose of an expansion joint?

To allow for movement and expansion of materials in a structure.

Define dead loads.

Permanent loads acting on a structure, including the weight of materials.

What are live loads?

Temporary loads applied to a structure, such as occupants and furniture.

Explain buckling in structural terms.

Failure mode characterized by sudden lateral deflection of a member under compression.

What is reinforcement in concrete?

Adding materials like steel to enhance the tensile strength of concrete.

Define modulus of elasticity.

A material property indicating its ability to deform elastically under stress.

What is a cross-section in structural engineering?

A vertical or horizontal slice through a structure used for analysis.

Explain how composite materials are used in construction.

Combination of materials to achieve improved strength, durability, or weight savings.

What is a structural detail?

Specific design elements and connections in a structure.

Define the term 'load combination.'

Different combinations of loads considered for structural design.

What is dynamic analysis in structural engineering?

The study of structures under time-varying loads such as wind and seismic activity.

Explain redundancy in structural systems.

Incorporating additional structural elements to ensure stability in case of failure.

What is the role of an architect in construction?

To design buildings and ensure they meet aesthetic and functional requirements.