Engineering Know-How: Lessons from Earthquakes and Rules for Seismic Design - Dynamic Behavior of Concrete and Seismic Engineering - page 333

Figure 9.9. Failure of a column due to shear load
Figure 9.10. Failure of a short column
The influence of shear load can be especially prominent in short columns, as
shown in Figure 9.10. In such a situation (for example, in ventilation spaces), an
imposed horizontal strain results in a prominent shear load, because the bending
length is limited and the column is stiff.
A similar phenomenon may also take place in short piers cut into a wall by
openings (Figure 9.11).
Figure 9.12 shows the deficiency of a column section with regard to
compression. The longitudinal reinforcements have suffered instability caused by
compression. They are not held firm by the concrete cover, which is ejected because
the stirrups are too widely spaced. The buckling force within the reinforcements is