Question

Which of the following would be most effective in buildings to withstand seismic loads?

• A. A framed building structure, with plan having interlocking octagons
• B. A rectangular framed structure, with shear walls
• C. Heavyweight construction with higher mass
• D. Avoiding base isolation of the building from foundation

Hint:

Seismic safety prefers structural simplicity and stiffness: - Keep the building layout simple and symmetric (like a clean rectangle). - Use structural shear walls to act as an unyielding backbone against horizontal shaking. - Keep the structure light, because more weight means a larger destructive force is generated during shaking!

Answer 1

The Correct Option is B

Concept: Seismic engineering relies on three core principles to ensure a building survives earthquake lateral forces: simple structural symmetry, adequate structural stiffness to limit lateral drift, and energy dissipation capacity (ductility). Earthquake shaking induces inertial lateral shear forces inside a building. According to Newton's second law of motion: \[ F = m \cdot a \] Where \(F\) represents the induced seismic inertial force, \(m\) is the mass of the building, and \(a\) is the ground acceleration.

Step 1: Evaluating the structural performance of option (B).
A rectangular framed structure provides a highly regular, predictable load path. When combined with shear walls (stiff vertical reinforced concrete walls designed to handle lateral forces), the building's lateral stiffness increases drastically. These shear walls act as sturdy vertical cantilevers that absorb the massive ground-shaking horizontal shears, keeping lateral displacements minimal and preventing structural collapse.

Step 2: Disproving the alternative configurations.

• Interlocking Octagons: Complex, irregular geometries with sharp re-entrant corners create massive structural stress concentrations and torsional forces during an earthquake, making them unfavorable.
• Heavyweight Construction: Increasing the mass (\(m\)) directly increases the seismic inertial forces (\(F\)) acting on the building, making it more vulnerable to heavy damage during ground acceleration.
• Avoiding Base Isolation: Base isolation is one of the most effective modern structural techniques available to protect a building. It detaches the superstructure from the ground movements via flexible bearings. Avoiding it removes an excellent layer of seismic defense. Therefore, a symmetrical rectangular framed structure incorporating structural shear walls is the most effective approach to withstand seismic loads safely.