Engineering Know-How: Lessons from Earthquakes and Rules for Seismic Design - Dynamic Behavior of Concrete and Seismic Engineering - page 330

inside the hinges counterbalances resistant moments, and whether sufficient ductile
rotation can take place. Figure 9.3 shows a case in which the piles were able to
absorb the imposed displacements without rupture.
Figure 9.4. Rupture of a column due to the shock between two neighboring structures
Two dynamically independent blocks can shock each other if the hinge
separating them is not open enough. Figure 9.4 shows local bending due to a shock
inside a column. The phenomenon can lead to total building collapse.
9.2.2. Problems linked to local under-design
Figure 9.5 shows a section at the head of a column that has been broken because
of the horizontal load transmitted to it. The section has several features that
contribute to this poor performance: smooth construction joints with little strength in
the concrete to withstand the shear load, no concrete confining reinforcements and
insufficient longitudinal reinforcements. No rotation ductility could be induced
because of these deficiencies, and the reinforcements broke in traction in the joints,
which opened because the rotation imposed was localized.
Figure 9.5. Rupture of a section due to insufficient longitudinal reinforcements