Masonry Magazine April 1986 Page. 35
Structural Walls
Reinforced concrete strucural walls are not common in Mexico City, probably because of the relatively low cost of masonry infilling. Several reinforced concrete parking garages with structural walls were examined, none of which seemed to have suffered significant damage.
Masonry
Mexico City has very few reinforced masonry buildings of the type commonly used in the United States. Low-rise, unreinforced masonry construction is very common for houses, apartments and commercial buildings, and the oldest construction in Mexico City is of this type. Many stone masonry churches have been standing for several hundred years, and many residences and commercial buildings are close to 100 years old. Such buildings generally suffered very little damage. This may have been less a function of their general structural integrity than of the fact that their fundamental periods of vibration were shorter than the characteristic periods of the lake zone ground motion. Nevertheless, such construction generally behaved very well.
As noted above, the other most common use of masonry in Mexico City was for unreinforced infills. While a number of the medium- and high-rise buildings did suffer infill damage, infills generally had a beneficial effect on structural performance [3.2]: by increasing a structure's lateral stiffness, they reduced its fundamental period of vibration, and therefore decreased the response to the earthquake.
It must be emphasized that the generally beneficial effect of this stiffening was due to the unusual filtering characteristics of the clay deposits underlying Mexico City. In other seismic regions, stiffening a structure may increase the inertial forces on a structure. The effects of infilling cannot be completely characterized in terms of modification of structural period. Infills which are distributed asymmetrically over the plan area of the building, or which fail asymmetrically, can induce unanticipated torsion. Similarly, infills which are terminated above the base of a structure can create an undesirable soft story.
Specific Examples of Structural Performance in Mexico City
Reinforced Concrete
1) The Old National Lottery Building, west of the intersection of Reforma and Avenida Juarez. This building exhibited a general lack of structural integrity. Columns were pulled away from slabs.
2) Recently completely cast-in-place reinforced concrete shear wall and frame parking garage directly west of the Pino Suarez complex came through the earthquake with no apparent damage. The building is a ten-story stiff shear wall structure.
3) Hotel El Presidente, at the northeast corner of Amberes and Hamburgo, in the Zona Rosa (Fig. 1). Note the visible facade damage involving lost veneer, and shearing at construction joints at floor levels. The orthogonal effects on corner buildings generally cause significant damage.
4) Collapsed building west of Pino Suarez complex on Fray Servando Street (Fig. 2). The total collapse of the upper portion of the structure made it impossible to determine the cause of the failure. The 13-story building in the background performed well with shear cracking to the brick infill walls the only apparent damage.
5) Corner of Dinamarca and Chapultepec Streets. This seven-story building overturned above the first floor and collapsed onto Chapultepec Street. It was a very narrow building, eccentric in plan, and open on the street side. It probably collapsed due to eccentricity, plus the failure of lower story columns due to the opening of the first floor facade.
6) Secretariate of Communications and Transport Ministry (SCT) Building, which was heavily damaged at the sixth floor. This was the only facility where the IMI team was denied site access. This and other photographs were taken from the outside. Damage to this structure disrupted telecommunications between Mexico and the outside world.
7) Twelve-story apartment building at the corner of Durango Street and Plaza Rio de Janeiro shows a first-floor column with a hinging region formed at the bottom. The building was severely damaged, but did not collapse.
FIG. 1: Building at the corner of Amberes and Hamburgo in the "Zona Rosa" with infill walls was damaged but did not collapse.
columns on the north side of the tower have failed in tension and the upper portion of the structure is displaced about 10 feet from the bottom three floors.
The Latino Americana building, built between 1950-1956 and 47 stories high, has a structural steel frame and is founded on bearing piles. This building performed satisfactorily with only a few broken windows.