Structural Analysis & Design Flashcards

According to ASCE 7, which load combination governs for a building subjected to dead load (D) and live load (L) using strength design (LRFD)?

Answer: 1.2D + 1.6L

The ASCE 7 LRFD combination 1.2D + 1.6L is typically the controlling factored load combination for gravity loads.

The degree of static indeterminacy of a structure is defined as:

Answer: The number of unknowns minus the number of independent equilibrium equations

Degree of indeterminacy = (number of unknowns) − (number of available equilibrium equations); it tells how many extra equations are needed.

In reinforced concrete design, the Whitney stress block depth 'a' used in ACI 318 is related to the neutral axis depth 'c' by:

Answer: a = β₁ × c

ACI 318 uses a rectangular stress block of depth a = β₁c, where β₁ depends on concrete compressive strength.

For a steel W-shape beam in AISC LRFD, the design flexural strength is φMn, where φ equals:

Answer: 0.90

For flexure in steel design per AISC 360, the resistance factor φb = 0.90.

An influence line for a structure shows how a response quantity (e.g., reaction, shear, or moment) varies as:

Answer: A unit load moves across the span

An influence line is a diagram showing the variation of a structural response at a specific point as a unit load traverses the structure.

The virtual work method (unit load method) for computing beam deflections uses which energy principle?

Answer: The actual internal work equals the virtual external work when virtual forces are in equilibrium

The unit load method equates the virtual external work (1 × δ) to the virtual internal work (∫mM/EI dx), where virtual forces satisfy equilibrium.

Which type of structural connection is designed to transfer moment, shear, and axial force between connected members?

Answer: Moment (rigid) connection

A moment (rigid) connection is designed to resist and transfer bending moment, shear, and axial force, maintaining the angle between connected members.