The structure is irregular in plan having three re-entrant corners, and is regular in elevation. The short side is 11.45 m in 2 bays and the long side is 28.70 m in 6 bays. Story heights are 2.65 m, the floor system is a waffle flat slab of 33 cm. The ...

Prepared By: Miguel Robles
Occupancy: Residential
Year Built: 1979
Height: 21.37 m
Number of stories: 8
Stories below ground: 1
Size: 2144 sqm
Original Code:
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: Frames with Masonry Infill
Other Load System:
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: Xochicalco 287, Narvarte, Benito Jurez, 03020
Latitude: 19.385171
Longitude: -99.154806


8-story residential building

Earthquake Information



Earthquake Date 31309
Moment Magnitude 8.1
Epicentral Distance 379.9
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 0.17g north-south direction, 0.17g east-west direction.
Ground motion recording stations SCT (Secretara de Comunicaciones y Transportes).
Distance to station 1.25
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

The damage was concentrated in the ground floor and extended up to the fifth level. The most significant damage consisted of shear cracking on the columns. There was no evidence of damage to the flat slab. The partition walls were severely damaged. The masonry walls on the edges facing the property line of the neighboring buildings were in very good condition (Meli and Lopez, 1986).

Damage state description

The most significant damage consisted in shear cracking on columns that also presented vertical cracks due to axial loading. Slab damage was light showing just few cracks on the top. Failures in masonry walls was concentrated in the north-south direction. The walls in the east-west direction did not show any evidence of damage (Meli and Lopez, 1986).

Summary of causes of damage

1. The damage was concentrated in the ground floor which had just a few masonry walls. This indicates that it might have been a soft/weak first story. 2. Concrete strength tests indicate high variability and the lowest values coincide with the stories that sustained most of the damage. 3. There is no evidence of adverse effects due to the plan irregularity. (Meli and Lopez, 1986)

Observed Design and Construction Characteristics


Construction Quality

MaterialsNotesContribution to Damage
Concrete Low concrete strengths at most damaged stories
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 Irregular in plan
Perimeter boundary Re-entrant corners
Diaphragm Openings
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story Fewer masonry walls in the first story
Weak story Most of the damage concentrated at the ground level
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system
Mass distribution
Change in stiffness

OtherNotesContribution to Damage
Other Factors Configuration

Lateral Load Resisting System‐General

StrengthNotesContribution to Damage
Overall lack of strength

StiffnessNotesContribution to Damage
Extreme Flexibility

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

Lateral Load Resisting System‐Frames

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

BeamsNotesContribution to Damage
Strength relative to columns
Shear controlled behavior
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

Lateral Load Resisting System‐Shear Walls

ShearNotesContribution to Damage
Diagonal tension/compression
Sliding Shear

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
Surface Rupture

OtherNotesContribution to Damage
Pile/Pier tension capacity

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 LR08-06).
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, 2012.

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