Observations from EERI/PEER Team

Figure 1.

Facades of unreinforced masonry structures show cracks varying in severity, from loss of plaster to separation of the walls from the structure (Figure 1). In this last case, the structural integrity of the wall, the load-bearing system, is compromised. Some of the structures in downtown L’Aquila that show this type of failure in several of their facades might have to undergo demolition. In isolated cases, the collapse of masonry structures in the old center of L’Aquila was complete. Partial structural collapses of walls or cornices were more frequent.

 

Figure 2.

Masonry structures that displayed cross-ties (catena in Italian), showed a much better resistance provided that the lateral walls were properly constructed (Figure 2).

From EERI/PEER Team: Damage to Concrete Structures

Figure 3.		Figure 4.

In older building code specifications, column-beam connections were allowed to be designed with smooth rebars that provide insufficient bonding with the concrete such as shown in figure 3. Failed connections also displayed widely-spaced, small-diameter stirrups, that cannot prevent the buckling of longitudinal rebar in columns. This has been the cause of most of the collapses that we have seen in the field, such as in figure 4.

Figure 5.

The figure 5 shows a spectacular pancake of the third onto the second story due to the failure of all the beam-column connections (as described above).

Figure 6.

This is a textbook example of pounding effect between two neighboring structures (Figura 6). The roof of the 2-story building hits the column of the adjacent 4-story structure causing the complete failure of all the columns at that level. Note that the third and the fourth story essentially show no damage.