Structural Analysis and Design
Structural questions test both conceptual understanding and the ability to select the governing design case. Candidates should be fluent in load paths, statics of determinate and indeterminate systems, influence lines for moving loads, and the behavior of frames, trusses, and continuous beams. Understand limit-state design: ultimate limit states (strength, stability, fatigue) and serviceability limit states (deflection, vibration, cracking). Know how partial safety factors combine permanent, variable, and accidental actions, and how load combinations are formed.
For reinforced concrete, know the assumptions of the design of sections in bending, the role of ductility, and the difference between under-reinforced and over-reinforced behavior. For steel, understand buckling, lateral-torsional buckling, and the importance of effective lengths. For seismic design, grasp capacity design, ductility classes, and the concept of a hierarchy of resistances so that a controlled mechanism forms.
Traps
A common trap is asking for the governing combination when several are plausible; always check both maximum load and minimum load cases (uplift, stability against overturning). Another is confusing characteristic and design values, or mixing units (kN versus kN/m versus kN/m²). Diagrams showing a fixed-end frame often hide a hinge or a support settlement that changes the analysis entirely.
Worked example
For a simply supported beam with span L under uniform load w, the maximum bending moment is wL²/8 at midspan and shear is wL/2 at supports. If the beam becomes continuous over two equal spans, the support moment is approximately wL²/8 (hogging) and the midspan sagging moment is about wL²/16-demonstrating how continuity redistributes moment and reduces midspan demand.