Foundations for a line of multiple columns constructed in a straight row: which type is most appropriate when loads are distributed along a line rather than concentrated at a single point?

Introduction / Context:
When columns are arranged in a straight line and carry similar loads, it is often economical and practical to use a continuous foundation that supports the entire line. This spreads the load uniformly and simplifies construction, especially on soils of moderate bearing capacity.

Given Data / Assumptions:

• Multiple columns aligned in a single row.
• Loads are relatively uniform along the line.
• Soil bearing conditions allow a shallow continuous footing.

Concept / Approach:
A strip footing (continuous footing) is a long footing that runs beneath a line of columns or a load-bearing wall. It distributes loads along length and is ideal where the structural layout presents a linear load path. Alternatives such as isolated pads or rafts are selected for different layouts (point loads scattered or whole-plan coverage).

Step-by-Step Solution:
Identify the load path: a linear sequence of column reactions.Select a footing that integrates these reactions along one axis: a strip footing.Size width based on allowable soil bearing pressure and service load combinations; check bearing, sliding, settlement, and shear/bending within the footing strip.

Verification / Alternative check:
Compare with a raft when coverage over a large area or poor soils is needed; isolated pads if columns are far apart; strap footings for eccentric cases combining adjacent pads. The linear column layout favors a strip footing in common practice.

Why Other Options Are Wrong:

• Isolated pads: suited to discrete column loads with separation.
• Raft: used when the entire building footprint needs support or soil is very soft; not just a single row.
• Strap: connects two pads to control eccentricity, not for a continuous row.
• “Combination of the above for a single column” does not fit the scenario.

Common Pitfalls:
Ignoring differential settlement along the strip, omitting temperature/shrinkage steel, or failing to check punching or two-way shear under columns on the strip.

Final Answer:
Strip footing (continuous footing under the row).