The building has a two story height and is supported by 39 reinforced concrete columns and the column dimension is 200 x 200 mm. The school is comprised of 8 different rooms. A sketch of the school building layout is provided on next page. Note that this ...

Prepared By: Edwin Lim
Occupancy: Education
Year Built:
Height:
Number of stories: 2
Stories below ground: unknown
Size: 408 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 : Spread Footings
Other Foundation :
Country: Indonesia
State: West Sumatra
City: Padang
Street: Sutan Syahrir street
Latitude: -0.963718
Longitude: 100.379282


 

Elementary School Building

Earthquake Information

 

 

Earthquake Date 40086
Moment Magnitude 7.6
Epicentral Distance 63.95
Local Intensity VII MMI
Site Description "According to Kastowo et al, 1973, the coastal plains of Padang and Pariaman are underlain by quaternary alluvium deposits, consisting of silt, sand, gravel and remnants of pumice tuff. Based on preliminary information of soil boring in Padang, the soil consists of medium dense to dense silty sand and stiff to very stiff silt with a relatively low ground water level. In addition, in the area around Batang Arau river, the site conditions include undocumented fills consisting of loose, saturated fine sand, which were placed as part of the site development" (EERI newletter, 2009).
PGA Lateral 0.4 (g)
PGA Vertical None (g)
SaT
Ground motion recording stations Padang (BMKG)
Distance to station 10.83
Station Latitude -0.9118
Station Longitude 100.4617
Ground Motion Summary "The southern Sumatra earthquake of September 30, 2009 occurred as a result of oblique-thrust faulting near the subduction interface plate boundary between the Australian and Sunda plates. At the location of this earthquake, the Australian Plate moves north-northeast with respect to the Sunda plate at a velocity of approximately 60 mm/yr" (USGS, 2012). "According to slip model developed by USGS, the maximum slip within the rupture zone is about 9 m. This, together with the seismic moment (about 2.6 x 10^20 N-m), suggests a high maximum slip rate, as well as strong radiated energy" (EERI newsletter, 2009). There is one strong motion recording station around this region. It is located on the mountain base with stiff soil and it is located 12 km away from the coast. The PGA of this ground motion is 0.3g and has shown 20 second strong shaking. This ground motion record will be higher in intensity in Padang city, since it has softer and deeper soil (EERI Newsletter, 2009).

 

Damage Information

 

 

Performance summary

During the 2009 Padang earthquake, this school building did not collapse. However, some damage could be observed in both the structural and non-structural components.

Damage state description

The structural damage in the building primarily occurred in the column and beam-column connection. In the column, the damage could be observed in the top and bottom part close to the joint. This damage ranged from light to heavy spalling of the concrete cover. In addition, some cracks were observed in the beam and column connection. Hairline cracks were also observed in the infilled masonry and the connection between the infill wall and RC-frame.

Summary of causes of damage

The main causes of the damage in this building were: 1. Lack of transverse reinforcement in columns 2. Poor details in the beam-column joint 3. Captive column effect

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete
Reinforcing steel

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Rebar Lack of transverse reinforcement bar in columns and poor development length/lap splices
Field variance with design documents
OtherNotesContribution to Damage
Other Factors Construction Quality

Configuration

Plan IrregularitiesNotesContribution to Damage
Torsion
Perimeter boundary
Diaphragm
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
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
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
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

Improved Performance

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

The main retrofit option applied to this building was to increase the development length in the beam-column joint. Furthermore, additional stirrups were placed in the structural elements near the beam-column joint. This retrofitting method was selected because most of the damage during the Padang Earthquake occurred in the beam-column joints. Furthermore, this retrofit method is also efficient as it can be performed with a small number of workers and requires only simple tools. The infill masonry wall was repaired using cement grouting as most of the cracks were only hair-line cracks.

References

 

Fauzan, 2012. Analisis Metode Pelaksanaan Retrofitting pada Bangunan Sederhanad (Studi Kasus: SD Negeri 43 Rawang Timur, Padang),Jurnal Rekayasa Sipil,8, No.1.


Earthquake Engineering Research Institute (EERI), 2009. The Mw 7.6 Western Sumatra Earthquake of September 30, 2009. Learning from Earthquakes, EERI Special Earthquake Report.


http://earthquake.usgs.gov/earthquakes/eqinthenews/2009/us2009mebz/
United States Geological Survey (USGS), 2009.Magnitude 7.6 - Southern Sumatra, Indonesia (31 July 2012)


http://www.bmkg.go.id/depan.bmkg
BMKG/USGS (2009), September 30, 2009 strong ground motion record from Padang, recorded by BMKG and processed by USGS


http://www.gi-j.com/Serial%201/71-77-1p-rusnardi.pdf
Rusnardi, R., Kiyono, J., and Ono, Y., 2011. Estimation of Earthquake Ground Motion in Padang, Indonesia,International Journal of Geomat,1, No.1, 7177