The structure is a two-story building primarily used for class rooms and a chemistry lab. The building has 12 spans in the east-west direction and 3 spans in the north-south direction. It consisted of two stories and was separated into two modules at the ...

Prepared By: Miguel Robles
Occupancy: Education
Year Built:
Height: 8.26 m
Number of stories: 2
Stories below ground: 0
Size: 1430 sqm
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 : Unknown
Other Foundation :
Country: Peru
State: Ica
City: Ica
Street: Los Maestros, Ica
Latitude: -14.084711
Longitude: -75.733462


 

University San Luis Gonzaga

Earthquake Information

 

 

Earthquake Date 39309
Moment Magnitude 8
Epicentral Distance 121.8
Local Intensity VII MMI
Site Description Stratigraphic units can be seen in this zone that belong to the Cenozoic age of the Recent Quaternary, formed by sea deposits, alluvial, eluvial and eolic (Elnashai et al, 2008).
PGA Lateral 0.34 (g)
PGA Vertical 0.2 (g)
SaT
Ground motion recording stations ICA2 - Universidad Nacional San Luis Gonzaga (UNSLG)
Distance to station 0.52
Station Latitude -14.089
Station Longitude -75.732
Ground Motion Summary The earthquake occurred near the coast of central Peru. The epicenter (13.36S, 76.52W) was located about 45 km (25 miles) west-northwest of Chincha Alta or about 145 km (90 miles) south-southeast of Lima at 5:40 PM MDT, August 15, 2007 (6:40 PM local time in Peru) with a focal depth of 30.2 km. This earthquake occurred at the boundary between the Nazca and South American tectonic plates. The two plates are converging at a rate of 77 mm per year. The earthquake occurred as thrust-faulting on the interface between the two plates, with the South American plate moving up and seaward over the Nazca plate (USGS, 2012). The strong motion instrument located in Ica recorded peak ground accelerations of 0.34g north-south, 0.28g east-west and 0.20g vertical (Elnashai et al, 2008).

 

Damage Information

 

 

Performance summary

The first story columns of the structure were heavily damaged during the earthquake showing failure from interaction of shear, moment, and axial load. The columns in the west module were much more severely damaged than those in the right module, even though the layout of columns and beams were almost identical. Some of the infill walls experienced minor cracks and crushing (Kwon, 2008).

Damage state description

The first story columns of the west side of the structure were heavily damaged. Columns with less restraint from infill walls, CW15 and CW17, suffered less damage than columns with more infill wall restraint. Many columns completely lost their capacities to resist gravity loads. In particular, columns CW04, CW05, CW06, and CW07 were severely damaged and shortened due to loss of core concrete. The longitudinal bars buckled as the weak stirrups could not provide enough confinement to core concrete. Some of the infill walls experienced minor cracks and crushing at the corners (Kwon, 2008).

Summary of causes of damage

1. It is anticipated that infill walls in the first floor, overload in the second floor, and inadequate stirrups of the columns resulted in the failure of columns. 2. Masonry infill walls shortened the effective length of columns, which resulted in brittle shear failures. 3. Part of the structure was overloaded with partition walls on the second floor, which may have led to the crushing of columns below. 4. The longitudinal bars buckled as the weak stirrups could not provide enough confinement to core concrete. (Kwon, 2008)

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete
Reinforcing steel Smooth wires

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Rebar Only one #3 stirrup at the ends of the columns and widely spaced wires
Field variance with design documents
OtherNotesContribution to Damage
Other Factors Construction Quality

Configuration

Plan IrregularitiesNotesContribution to Damage
Torsion
Perimeter boundary Re-entrant corners
Diaphragm
Out-of-plane offsets in lateral resisting system
Non-orthogonal systems

Vertical IrregularitiesNotesContribution to Damage
Soft story
Weak story The damage was concentrated on the first story
Geometric variablility of lateral resisting system
In-plane discontinuity of lateral resisting system
Mass distribution
Setback
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
Collectors/Struts
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 Partition walls on the second floor overloaded part of the structure
Vertical load columns drift capacity
Interference of frame action by infill Masonry infill walls created captive columns

BeamsNotesContribution to Damage
Strength relative to columns There was no evidence of damage to beams; Cross section dimension was larger than columns
Shear controlled behavior
Continuity of longitudinal reinforcing
Loss of vertical capacity
Interference of frame action by infill beams

JointsNotesContribution to Damage
Interior
Exterior
Corner

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting System-Frames

Lateral Load Resisting System‐Shear Walls

ShearNotesContribution to Damage
Diagonal tension/compression
Sliding Shear
Flexure/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
Unreinforced
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
Liquefaction
Pounding
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

Unknown

Other Retrofit or Repair

Performance Level

Unknown

Hazard Level

Unknown

Retrofit or Repair Code

Unknown

Other Retrofit or Repair Code

Lateral Analysis

Unknown

Other Lateral Analysis

Design Strategy

Retrofit Summary

References

 

http://db.concretecoalition.org/static/data/6-references/PERU002_Reference_01.pdf
Kwon, O., 2008. "Damaging Effects of the Pisco-Chincha (Peru) Earthquake on an Irregular RC Building". The 14th World Conference on Earthquake Engineering, October 2008, Beijing, China.


https://www.ideals.uiuc.edu/handle/2142/9460
Elnashai, A., Alva-Hurtado, J., Pineda, O., Kwon, O., Moran-Yanez, L., Huaco, G., Pluta, G., 2008. "The Pisco-Chincha Earthquake of August 15, 2007; Seismological, Geotechnical and Structural Assessments". Mid-America Earthquake Center, Report No. 08-01.


United States Geological Survey (USGS). "Magnitude 8.0 - NEAR THE COAST OF CENTRAL PERU". Significant EQ Archive, 2012. http://earthquake.usgs.gov/earthquakes/eqinthenews/2007/us2007gbcv/


United States Geological Survey (USGS), 2008. "USGS ShakeMap: Pisco, Peru". ShakeMap Atlas, 2012. http://earthquake.usgs.gov/earthquakes/shakemap/atlas/shake/200708152340/