Building Design – Column design actions in multi-storey structures In a multi-storeyed building, reinforced concrete or steel columns must be proportioned to withstand which combination of design actions under relevant codes and load combinations?

Introduction / Context:
Columns are primary vertical load-carrying members. Modern design considers a full set of actions under stipulated load combinations. Neglecting any credible action may lead to unsafe designs, especially in tall and slender buildings where lateral effects can govern.

Given Data / Assumptions:

• Multi-storey frame with gravity and lateral loads.
• Applicable design codes require combinations of dead, live, wind, and seismic actions.
• Load factors and combination factors are applied as per code.

Concept / Approach:

Design actions on columns include axial force, biaxial bending, and shear arising from gravity loads (dead and live) and lateral loads (wind and earthquake). Codes combine these using factored envelopes for Ultimate Limit State and service combinations for deflection/drift. Therefore, all listed loads must be considered in design to ensure strength and stability.

Step-by-Step Solution:

Verification / Alternative check:

Design examples show governing combinations often include lateral loads with reduced live load participation; seismic detailing provisions are mandatory in seismic zones.

Why Other Options Are Wrong:

Any single-load assumption is incomplete and unsafe. Both gravity and lateral actions must be checked.

Common Pitfalls:

Ignoring accidental eccentricities; neglecting slenderness and second-order effects; underestimating live load reduction rules.

Final Answer:

All of these.