MArch Master of Architecture Structural Systems in Architecture 2 — Questions and Answers
Question 1: A catenary curve, the natural form assumed by a hanging chain under its own weight, is used in arch design because:
- It produces the most aesthetic visual proportion
- An inverted catenary arch carries its load in pure compression with no bending (Correct answer)
- It maximizes the enclosed floor area beneath the arch
- It is the easiest curve to construct with masonry
Correct answer: An inverted catenary arch carries its load in pure compression with no bending
An inverted catenary perfectly distributes load through pure compressive axial force, eliminating bending moments that would require tensile resistance in masonry.
Question 2: What is the purpose of a moment-resisting frame (rigid frame) in structural design?
- To allow joints to rotate freely under load
- To transfer bending moments across beam-column connections for lateral stability (Correct answer)
- To prevent all vertical deflection in floor slabs
- To transfer loads only through diagonal bracing members
Correct answer: To transfer bending moments across beam-column connections for lateral stability
A moment-resisting frame has rigid beam-column connections that can transfer bending moments, allowing the frame to resist lateral loads without diagonal bracing.
Question 3: In shell structural design, a doubly curved surface such as a hyperbolic paraboloid (hypar) is structurally efficient because:
- Its curves can be formed only from straight lines of timber
- It carries loads primarily through membrane stresses (tension and compression) rather than bending (Correct answer)
- It eliminates the need for any foundation
- Its geometry guarantees equal spans in all directions
Correct answer: It carries loads primarily through membrane stresses (tension and compression) rather than bending
A doubly curved shell transfers loads through in-plane membrane action—axial tension and compression—rather than out-of-plane bending, using material far more efficiently.
Question 4: The slenderness ratio of a column (KL/r) is used in structural design to predict the column's susceptibility to which failure mode?
- Crushing failure from direct compression
- Euler buckling (lateral instability) under compressive load (Correct answer)
- Shear failure at the column base
- Tensile splitting along the column axis
Correct answer: Euler buckling (lateral instability) under compressive load
Higher slenderness ratios indicate columns that will buckle laterally before reaching material crushing strength, governed by Euler's buckling formula.
Question 5: In seismic design, the concept of 'ductility' in structural systems refers to:
- The ability of a material to conduct heat without fracturing
- The capacity of a structure to deform inelastically while maintaining load-carrying capability (Correct answer)
- The stiffness of a building that prevents any lateral movement
- The ability of a foundation to redistribute soil pressure
Correct answer: The capacity of a structure to deform inelastically while maintaining load-carrying capability
Ductile structural systems absorb seismic energy through controlled inelastic deformation without sudden brittle fracture, preventing catastrophic collapse.
Question 6: A prestressed concrete beam differs from ordinary reinforced concrete because:
- It uses no steel reinforcement
- Internal steel tendons are tensioned before service loads are applied to precompress the concrete (Correct answer)
- It relies on post-tensioned external cables only
- It uses a higher water-cement ratio for workability
Correct answer: Internal steel tendons are tensioned before service loads are applied to precompress the concrete
Prestressing introduces compressive stress into the concrete prior to loading, counteracting tensile stresses that would otherwise crack the concrete under load.
MArch Master of Architecture Structural Systems in Architecture 2
A catenary curve, the natural form assumed by a hanging chain under its own weight, is used in arch design because: