The building is the tower C (torre C) of a three office buildings complex. It has a basement and 15 stories above ground level. There is a smaller 2-story, approximately 20x20 m structure on the roof top for heavy machinery. The basement is 9 bays in t...

Prepared By: Miguel Robles
Occupancy: Commercial
Year Built: 1981
Height: 49.25 m
Number of stories: 15
Stories below ground: 1
Size: 31536 sqm
Original Code:
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: Moment Frame and Shear Wall Combination
Other Load System: Waffle flat slab Two shear walls in one direction
Vertical Load System: Waffle or pan-joist with columns
Other Vertical Load System:
Foundation : Piles or Piers
Other Foundation :
Country: Mexico
State: Distrito Federal
City: Mexico City
Street: Calle Eje 5 and Avenida La Viga
Latitude: 19.379596
Longitude: -99.121072


15-story office building

Earthquake Information



Earthquake Date 31309
Moment Magnitude 8.1
Epicentral Distance 383
Local Intensity VIII MMI
Site Description "Mexico City lies in the southwestern quadrant of a broad basin which was originally formed by block faulting of an uplifted plateau. It was subsequently blocked by successive lava flows that formed a dam across the valley just south of Mexico City. This dam resulted in the formation of Lake Texcoco, which slowly began to fill with silt, clay, and ash from nearby volcanoes. This lake bed has been used for the expansion of Mexico City. Today much of the city rests on lake deposits, which overlay older sedimentary sequences" (NBS, 1987).
PGA Lateral 0.17 (g)
PGA Vertical None (g)
SaT 0.72g longitudinal direction, 0.55g transverse direction.
Ground motion recording stations SCT (Secretara de Comunicaciones y Transportes).
Distance to station 3.22
Station Latitude 19.394
Station Longitude -99.148
Ground Motion Summary "The September 1985 Michoacn, Mexico earthquake occurred as a result of the subduction of the Cocos Plate along the Middle American Trench beneath the North American and Caribbean plates. The earthquake initiated at 18.2N, 102.6W, with a focal depth of approximately 18 km, and propagated approximately 170 km to the southeast. Because of the unrelieved accumulated strains caused by the slip movement (about 57 mm/year), the area was believed to have the potential for a major earthquake. A preliminary estimate of the seismic moment for the main shock is 0.9-1.5X10^28 dyne-cm (0.9-1.5X10^21 N-m), yielding a moment magnitude of 7.97 to 8.12 for the main shock" (NBS, 1987).


Damage Information



Performance summary

There was moderate damage in the first four levels. Almost all the damage was concentrated at levels 4 to 12, especially between axes D and H close to the shear walls. There was light damage to the columns and only a few large cracks were observed. Differential settlement in the slabs was very noticeable, especially in the central area around the stairs and elevators core (Meli and Lopez, 1986).

Damage state description

The observed damage in slabs consisted in punching shear failures, spalling concrete and rebar buckling in some cases, shear failures in joists near the capitals especially in column E3 at several stories. Damage to columns consisted in minor shear cracking and only a few large cracks were found in the building. There was heavy damage in one corner at the top story probably due to pounding with adjacent tower B (Meli and Lopez, 1986).

Summary of causes of damage

1. The building was extremely flexible due to low stiffness of the waffle slab and greater ground floor story height. 2. The shear walls concrete core settled due to inadequate proportioning of the foundation. 3. Insufficient strength of the waffle flat slab resulted in punching shear failure at several locations in the building. 4. Shear cracking in columns might be the result of poor rebar detailing, especially with the transverse reinforcement. (Meli and Lopez, 1986)

Observed Design and Construction Characteristics


Construction Quality

MaterialsNotesContribution to Damage
Reinforcing steel

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Field variance with design documents
OtherNotesContribution to Damage
Other Factors Construction Quality


Plan IrregularitiesNotesContribution to Damage
Torsion Change in the center of mass because of the setbacks
Perimeter boundary
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story Story height of the ground floor was greater
Weak story
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system
Mass distribution Change of the center of mass because of the setbacks
Setback At levels 1 and 3
Change in stiffness

OtherNotesContribution to Damage
Other Factors Configuration

Lateral Load Resisting System‐General

StrengthNotesContribution to Damage
Overall lack of strength Several shear failures in the waffle flat slab

StiffnessNotesContribution to Damage
Extreme Flexibility Large periods

Load PathNotesContribution to Damage
Anchorage of nonstructural elements
Out-of-plane capacity of walls
Diaphragm chords
Diaphragm openings

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-General Poor ductile detailing, especially with transverse reinforcement.

Lateral Load Resisting System‐Frames

ColumnsNotesContribution to Damage
Shear strength Small shear cracks
Flexural strength Small flexure/shear cracks
Axial load ratio
Vertical load columns drift capacity
Interference of frame action by infill

BeamsNotesContribution to Damage
Strength relative to columns
Shear controlled behavior Shear failures in waffle flat slab stems
Continuity of longitudinal reinforcing
Loss of vertical capacity
Interference of frame action by infill beams

JointsNotesContribution to Damage

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Frames Punching shear failures

Lateral Load Resisting System‐Shear Walls

ShearNotesContribution to Damage
Diagonal tension/compression Diagonal crack in the middle of the walls
Sliding Shear
Flexure/shear Cracks at the edge of the walls

FlexureNotesContribution to Damage
Compression zone buckling capacity
Discontinuity of wall
Boundary reinforcing fracture/buckling
Boundary Reinforcing at openings

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Shear Walls

Lateral Load Resisting System‐Infills

InfillsNotesContribution to Damage
Interference with frame action
Out of plane
Attachment to framing

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting Systems-Infills

Lateral Load Resisting System‐Other

FoundationsNotesContribution to Damage
Pounding At one of the top story corners with adjacent tower B
Surface Rupture

OtherNotesContribution to Damage
Pile/Pier tension capacity Shear walls concrete core settlement

MiscellaneousNotesContribution to Damage
Spread footing capacity
Other Factors Lateral Load Resisting Systems-Other-Foundations

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting Systems-Other-Misc

Repair and Retrofit Information


Type of Retrofit or Repair


Other Retrofit or Repair

Performance Level


Hazard Level


Retrofit or Repair Code


Other Retrofit or Repair Code

Lateral Analysis


Other Lateral Analysis

Design Strategy

Retrofit Summary



Meli, R., Lopez, C., 1986. "Evaluacion de los Efectos de los Sismos de Septiembre en la Ciudad de Mexico, Parte II, Anexo". Instituto de Ingenieria, UNAM. (Building LR15-08).
National Bureau of Standards (NBS), 1987. "Engineering Aspects of the September 19, 1985 Mexico Earthquake". NBS Building Science Series 165.

United States Geological Survey (USGS), 2008. "USGS ShakeMap: Michoacan, Mexico". ShakeMap Atlas. (Accessed 2012)

"Mexico". 18.41 N and 102.37 W. Google Earth/USGS, 2012.