This building, typically, consists of concrete frames in 3 meter modules. This typical building may have three spans in wide (9 meters) and ten spans in long (30 meters). Some cast-in-place beams approximately 75 cm on-center connect the frame beams. Thes...

Prepared By: Edwin Lim
Occupancy: Residential
Year Built:
Number of stories: 4
Stories below ground: 0
Original Code:
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: Frames with Masonry Infill
Other Load System:
Vertical Load System: Slabl_Beams_Columns
Other Vertical Load System:
Foundation : Spread Footings
Other Foundation :
Country: Algeria
City: El-Asnam/Chlef
Latitude: 36.17308
Longitude: 1.334099


3 - 4 Story Typical Apartment Building

Earthquake Information



Earthquake Date 29504
Moment Magnitude 7.3
Epicentral Distance 4.035
Local Intensity IX MMI
Site Description El-Asnam is located in a broad alluvial valley flanked to the north and south by ranges of hills that rise to a height of approximately 1000 m. No major slope failures were observed in the city of El-Asnam. (Source: Bertero & Shat, et al, 1983)
PGA Lateral 0.4 (g)
PGA Vertical 0.5 (g)
Ground motion recording stations An earthquake ground motion was recorded by IZIIS Center at Skopye (Macedonia) for this earthquake. After this earthquake event, some ground motion recorders were installed at the field to measure the aftershocks. From this record, it is interesting to note that the vertical acceleration was larger than the horizontal acceleration. (Source: Bertero & Shah, et al, 1983)
Distance to station None
Station Latitude None
Station Longitude None
Ground Motion Summary The main shock was produced by displacement on a northeast trending thrust fault that dips to the northwest; this fault has subsequently been named the Oued Fodda fault after the closest principal city aligning its surface trace. Numerous secondary fissures and normal faults occur on the upthrown block of the main thrust within a zone that extends to 2 km from the main trace. Surface faulting also occurred along Beni Rached fault, a normal fault that may also be a secondary fault. Surface faulting occurred along the Oued Fodda fault, which is located south and east of El-Asnam; the closest distance of surface trace to El-Asnam is about 7 km. The surface faulting occurred along a zone that extends at least 30 km. Secondary normal faulting and ground cracking suggests that the primary thrust fault rupture may extend an additional 2 km to the southwest and 4 km further eastward to El-Abadia, suggesting an overall rupture length of 35 km. In most places, the primary fault is a low angle thrust that dips 10 to 20 degree northwest. Locally, the dip of the primary fault steepens to form a reverse fault that dips as steeply as 55 degree. Because there is no record for this main event, there was much debate regarding the earthquake's duration. According to some, the strong motion of the main shock lasted over 15 seconds, while the total duration lasted about 35 to 40 seconds. (Source: Bertero & Shah,et al, 1983)


Damage Information



Performance summary

This type of building performed very poorly in the El-Asnam earthquake. In general, most of these buildings were subjected to collapse in the "vide sanitaire" area (crawl space area). Several remaining standing buildings were inclined as much as 20 degree and dropped up to 1 meter, producing damage in the first story. (Source: Bertero & Shah, et al, 1983)

Damage state description

The main typical damage in this building was indicated by the shear-off of the stubby column in the vide sanitaire area. Also, the upper story was subjected to light damage at the concrete frame and infills. (Source: Bertero & Shah, et al, 1983)

Summary of causes of damage

The major cause of this damage was not only caused by the soft story, but also the inadequate shear capacity of the stubby column to resist the forces induced by the earthquake. (Source: Bertero & Shah, et al, 1983)

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
Perimeter boundary
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story
Weak story
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system Discontinuity of perimeter wall in crawl space area.
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
Flexural strength
Axial load ratio
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

None (demolished/abandoned)

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

Bertero, V.,Shah, H.,et al. 1980. El - Asnam, Algeria Earthquake of October 10, 1980 - A Reconnaissance and Engineering Report. NRC & EERI.
United States Geological Survey (USGS), 2012.Significant Earthquakes of the world 1980 (Accessed: 10 August 2012).
Colored images are courtesy of the National Information Service for Earthquake Engineering, EERC, University of California, Berkeley