Structural Systems Flashcards

In seismic design, what does 'ductility' mean and why is it desirable?

Answer: The ability of a structure to deform significantly without collapse, absorbing seismic energy

Ductile structures deform plastically, absorbing earthquake energy through yielding rather than brittle fracture, protecting occupants even when the structure is damaged.

What is the purpose of 'drag struts' or 'collector elements' in a lateral force resisting system?

Answer: To collect and transfer diaphragm forces into shear walls or braced frames

Collector elements run parallel to the lateral load direction, gathering shear from the diaphragm and delivering it into the concentrated lateral force resisting elements like shear walls.

A geotechnical report's 'allowable bearing capacity' tells the structural engineer what?

Answer: The maximum load per unit area that the soil can safely support under a foundation

Allowable bearing capacity, expressed in pounds per square foot or kPa, sets the upper limit for foundation pressure, directly sizing spread footings or mat foundations.

What is 'load path' in structural design?

Answer: The continuous route through which applied loads travel from their point of origin to the foundation

Load path traces how forces flow from floors and roofs through beams, columns, and shear walls to foundations, with every element along the path needing to be designed for its share.

Which roof framing system uses a series of triangulated members to span long distances efficiently?

Answer: Truss

Trusses use triangulated arrangements of members in tension and compression to span long distances at shallow depths with far less material than a solid beam of equivalent span.

In structural design, what does 'factor of safety' represent?

Answer: The ratio of a structure's actual capacity to the expected load, providing a margin against failure

Factor of safety quantifies how much stronger a structure is than the minimum needed, accounting for load uncertainties, material variability, and modeling simplifications.