Structural Analysis and Design
Structural Analysis and Design tests your ability to read CTE DB-SE, apply actions and combinations, and check that a member or foundation is safe and serviceable.
Limit states
ELU (ultimate) checks resistance and stability; ELS (serviceability) checks deflection, cracking and vibration. Actions are permanent (G), variable (Q) and accidental (A). For persistent and transient situations, CTE DB-SE uses 1.35G + 1.50Q for the fundamental combination.
Member checks
A simply supported beam carries bending, shear and deflection. Deflection limits depend on the element and finish (commonly L/250, L/300 or L/400). Foundations must check bearing capacity, sliding and overturning.
Worked example
A 6 m simply supported beam has permanent load 10 kN/m and variable load 5 kN/m. Design load qd = 1.35(10) + 1.50(5) = 21 kN/m. Maximum moment M = qL²/8 = 21 × 36 / 8 = 94.5 kN·m. Maximum shear V = qL/2 = 63 kN. Compare these with the member resistance, then check deflection under characteristic loads.
Traps
- Using characteristic loads in an ELU check.
- Mixing ELU and ELS combinations.
- Forgetting self-weight or partition allowances.
- Mixing kN, kN·m and kN/m.