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MDOF Modal Analysis + SRSS/CQC

n-story shear frame · Modal participation factors Γr · Peak modal responses · SRSS and CQC combination rules · Chopra §12–13

n-Story Shear Frame

Number of stories n (max 5)

Story mass m (kg) — uniform

Story stiffness k (N/m) — uniform

Damping ζ (all modes)

SDS (g) — TBDY 2018

SD1 (g)

Combination rule

Base shear Vb (SRSS/CQC)—

Combined floor displacements—

Chopra §12.4Γr=φᵣᵀMι/(φᵣᵀMφᵣ) — modal participation

Eq.(13.7)SRSS: u≈√(Σuᵣ²) — for well-separated modes

Eq.(13.8)CQC: u≈√(ΣΣρrs·ur·us) — for closely-spaced modes

TBDY 2018 Md.4.8Modal combination per Turkish seismic code

Preliminary educational tool. Verify results against textbook solutions.