This building is an 8-story building, including one basement floor located at a depth of 3.72 m underneath the ground. By just looking at the facade, this building seems to have well separated columns (4 meters apart). However, there is an 8 meter spacing...

Prepared By: Edwin Lim
Occupancy: Hotel
Year Built: 1994
Height: 31 m
Number of stories: 9
Stories below ground: 1
Size:
Original Code: Indonesian Seismic Code 1983 and Indonesian Concrete Code 1991
Modification: Unknown
Year Modified:
Code of Modification:
Lateral Load System: MomentFrame
Other Load System:
Vertical Load System: Slabl_Beams_Columns
Other Vertical Load System:
Foundation : Piles or Piers
Other Foundation :
Country: Indonesia
State: West Sumatra
City: Padang
Street: Bundo Kanduang Street
Latitude: -0.955211
Longitude: 100.358498


 

8-Story Building

Earthquake Information

 

 

Earthquake Date 40086
Moment Magnitude 7.6
Epicentral Distance 61.45
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 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 12.45
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

This building suffered some damages during the 2005 and 2007 earthquakes. After the 2005 earthquake, only non-structural damage was observed in this building. Previous to this event, there was already some pre-existing damage to the architectural/artificial brick masonry columns. After the 2007 earthquake, besides the damage to the non-structural elements and the artificial columns, structural damage could be observed at the base of the structural columns. After the 2009 earthquake, the major structural damage could be found at the first level near the elevator (Source: Gunara, 2011). According a different reference, during the 2009 event, this building was subjected to an excess of 80% non-structural damage (infill masonry, ceilings, door and window) from its undamaged condition. The structural damage could be observed at the middle part of the plan near the lift area. It was predicted that this damage reached 90% of the undamaged condition (Source: Ismail et al, 2011).

Damage state description

The major structural damage could be found on the columns, beams and slab in first and second floors. This damage induced deflection on the floor slab in the middle of the building for more than 25 cm (Source: Ismail et al, 2011). The other reference also states that the same damage condition existed around the elevator area in the first level. In addition, there was only one foundation column that suffered damage in its connection between the column and pile cap (H-9) when the building was subjected to the 2009 earthquake (Source: Gunara, 2011).

Summary of causes of damage

Based on a Static Equivalent and Response Spectra Analysis performed in accordance to the Indonesian 2002 building code conducted by Ismail et al, the column in this building did not have sufficient capacity to resist the combination of axial-moment and shear load that occurred in the structure. According to Gunara, the damage near the elevator area on level one was caused by the changing of load path from the shear wall in the basement to the column elements. This caused beams and columns in floors 2 through 4 to deflect toward the elevator (Source: Gunara, 2011). PT. Bina Raka Metindo also added that the high torsional response of the building caused by plan irregularity was highly possible to govern in the first mode of the building. This might cause concentrated stresses/loads in some elements (Source: PT Bina Raka Metindo).

Observed Design and Construction Characteristics

 

Construction Quality

MaterialsNotesContribution to Damage
Concrete
Reinforcing steel

ExecutionNotesContribution to Damage
Conveyance/placement of concrete
Rebar
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 In the plan view, the location of columns in the web of the mirrored Z-shape part is not orthogonal with the columns in the flange part.

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 Strong beam, weak column
Shear controlled behavior
Continuity of longitudinal reinforcing
Loss of vertical capacity
Interference of frame action by infill beams Inadequate flexural capacity

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 Unreinforced artificial column, infilled
Interference with frame action
Out of plane
Attachment to framing Lack of confinement from the framing either from the large area of infilled wall or connection between framing and wall

OtherNotesContribution to Damage
Other Factors Lateral Load Resisting Systems-Infills Large opening in masonry infilled wall (windows)

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

Based on the brief report provided PT Bina Raka metindo, the repairing/retrofitting strategy was mainly focused in the damage area around the elevator and the facade of the building.

References

 

http://www.ftsl.itb.ac.id/wp-content/uploads/2011/04/2.-Febrin-dkk-Vol.18-No.2.pdf
Ismail, F.A., Hakam, A., and Fauzan, 2011. Kerusakan Bangunan Hotel Bumi Minang Akibat Gempa Padang 30 September 2009,Jurnal Teknik Sipil,18, No.2, 119126


http://e-teknika.ft.unand.ac.id/index.php/jts/article/view/105/18
Fauzan, Zaidir, Nengsi, D.P, and Miswar, I., 2010. Analisa Pengaruh Dinding Geser Pada Struktur Bangunan Hotel Bumi Minang Akibat Beban Gempa,Jurnal Rekayasa Sipil,6, No.1


http://ft.uki.ac.id/images/sipil/MakalahSuparmanGunara.pdf
Gunara, S. and Huda N., "Kajian Hotel Bumi Minang di Padang terhadap Gempa Tahun 2005, 2007 dan 2009." Sistem Struktur Penahan Gempa dan Persyaratan Khusus untuk Bangunan Tidak Beraturan Universitas Kristen Indonesia. September, 2011.


PT. Bina Raka Metindo.Penyusunan Pedoman Teknis Retrofitting Bangunan Gedung, Indonesia.


http://nurilhuda87.wordpress.com/gempa-padang-studi-kasus-hotel-bumi-minang/hotel-bumi-minang-di-padang-kokoh-diterpa-gempa-th-2005-2007-dan-2009/
Nuril Huda Slawi. "Hotel Bumi Minang di Padang Kokoh Diterpa Gempa." Nuril Huda Slawi. (Accessed: 31 July 2012)


https://www.eeri.org/site/images/eeri_newsletter/2009_pdf/Padang-eq-report-NL-insert.pdf
Earthquake Engineering Research Institute (EERI), 2009. The Mw 7.6 Western Sumatra Earthquake of September 30, 2009. Learning from Earthquakes, EERI Special Earthquake Report.


EERI, 2011. Select photos from 30 September 2009 Padang, Indonesia Earthquake. Earthquake Engineering Research Institute Photo Library, Oakland, CA.


United States Geological Survey (USGS), 2009.Magnitude 7.6 - Southern Sumatra, Indonesia (Accessed: 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