Structural Design of G+3 RCC Building as per IS Standards Using ETABS

A: Governing principle: Design inputs must be consistent across controlling documents. Applied here: Slab thickness drives dead load, stiffness, and seismic mass, so reconciliation is mandatory before acceptance. Distractor B catches engineers who treat software output as authoritative without configuration control.

A: Governing principle: Seismic analysis is sensitive to mass and stiffness distribution per IS 1893. Applied here: A shifted mass centroid induces torsion even in symmetric frames, inflating column moments. Distractor C appeals to those mixing gravity load logic into dynamic analysis where it doesn’t apply.

A: Governing principle: Dead load equals material density times thickness. Applied here: 0.15 m × 25 kN/m³ gives 3.75 kN/m² before finishes. Distractor C traps those who silently add finishes without checking the loading definition.

A: Governing principle: Standard material notation follows IS 456 and IS 1786 conventions. Applied here: M25 refers to concrete characteristic strength, Fe500 to rebar yield strength. Distractor D catches those relying on legacy mix-ratio habits rather than grade-based design.

A: Governing principle: Base shear Vb = Ah × W where Ah = (Z/2)(I/R)(Sa/g). Applied here: Ah = (0.16/2)(1/3)(2.5) ≈ 0.213, giving Vb ≈ 2,133 kN. Distractor C tempts engineers who forget R in the denominator during quick checks.

A: Governing principle: Shear capacity depends on both concrete and stirrup detailing. Applied here: Even with enough flexural steel, excessive stirrup spacing leads to shear failure flags. Distractor D attracts those mixing serviceability proportions with strength checks.

A: Governing principle: Geotechnical parameters control foundation capacity. Applied here: Using the lower SBC avoids overstress until the soil report is officially updated. Distractor B catches engineers who over-trust downstream drawings without tracing source data.

A: Governing principle: Steel quantity scales with bending demand and span. Applied here: Residential slabs usually fall in the 3–4 kg/m² range for preliminary checks. Distractor D appeals to those extrapolating from beams or industrial floors without adjusting context.

A: Governing principle: IS 1893 limits storey drift to 0.004h under design seismic load. Applied here: 0.004 × 3,000 mm gives 12 mm allowable drift. Distractor B catches engineers mixing crack-width intuition with seismic deformation checks.