Seismic Survey and Condition Assessment of School Buildings ...
Seismic Survey and Condition Assessment of School Buildings ...
Seismic Survey and Condition Assessment of School Buildings ...
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<strong>Seismic</strong> <strong>Survey</strong> <strong>and</strong> <strong>Condition</strong> <strong>Assessment</strong> <strong>of</strong> <strong>School</strong><br />
<strong>Buildings</strong><br />
(Case Study Done in the Eastern Province, Sri Lanka)<br />
H.A.D.S.Buddika,<br />
Department <strong>of</strong> Civil Engineering, University <strong>of</strong> Peradeniya, Sri Lanka<br />
samithbuddika@gmail.com<br />
Ranjith Dissanayke<br />
Department <strong>of</strong> Civil Engineering, University <strong>of</strong> Peradeniya, Sri Lanka<br />
ranjith@civil.pdn.ac.lk<br />
Abstract<br />
Major economic consequences <strong>and</strong> losses <strong>of</strong> lives are evident in recent Tsunami tidal waves that<br />
ravaged several countries in the Indian Ocean Rim on December 26, 2004. Although considered a<br />
moderate seismic region, in Sri Lanka, the 2004 Tsunami claimed over 38,000 lives <strong>and</strong> investment<br />
need for post reconstruction strategy amounted to $2,089Mn. <strong>School</strong>s are playing vital role in every<br />
community. Disaster safe schools must be recognized as a basic human right. This statement is easy to<br />
make but difficult to accomplish Therefore, it is the high time to investigate the disaster vulnerability<br />
<strong>of</strong> important structures such as schools to withst<strong>and</strong> the future natural disasters.<br />
This paper summarizes the outcomes <strong>of</strong> seismic vulnerability assessment procedure carried out on<br />
schools in Eastern Province, Sri Lanka. The typical structural deficiencies found during the<br />
investigation are summarized in this paper. The main aim <strong>of</strong> this work is to identify the existing<br />
seismic vulnerable conditions in the school buildings, in order to establish detail investigation<br />
procedure to minimize the damages to withst<strong>and</strong> future disasters.<br />
Keywords: future disasters, rapid Visual Screening, structural deficiencies, vulnerability <strong>Assessment</strong>
1. Introduction<br />
<strong>School</strong>s are playing vital role in every community. The public school network in Sri Lanka is vast,<br />
with about 4.2 million children enrolled in over 9,790 public schools around the country. These<br />
schools contain a teaching force about 2 lacks [1] .<strong>Seismic</strong>ally safe schools must be recognized as a<br />
basic human right. This statement is easy to make but difficult to accomplish. Government <strong>of</strong>ficials<br />
<strong>and</strong> community stakeholders are accountable <strong>and</strong> morally responsible for acknowledging the necessity<br />
to improve seismic safety in schools <strong>and</strong> to act upon that knowledge. Forging alliances between the<br />
many groups involved in school administration <strong>and</strong> government can be an initial step towards<br />
significant safety improvements. These alliances can provide a multi-disciplinary approach to<br />
problem-solving, <strong>and</strong> bring added capacity <strong>and</strong> energy to accomplishing the daunting tasks <strong>of</strong> seismic<br />
assessment <strong>and</strong> reconstruction [1].<br />
Even though considered as a non-seismic region, Sri Lanka would expect maximum ground<br />
acceleration <strong>of</strong> 0.3g [2]. Recent catastrophic natural hazard, 2004 Tsunami claimed over 38,000 lives<br />
<strong>and</strong> investment need for post reconstruction strategy amounted to more than $2 billion in Sri Lanka.<br />
Therefore, it is the high time to prepare against future disasters because repair <strong>and</strong> reconstruction <strong>of</strong><br />
school buildings are difficult <strong>and</strong> expensive after earthquake, when government resources are restrain.<br />
Figure1: Tsunami memorial in school<br />
Figure 2: Memories after period <strong>of</strong> one year<br />
Those responsible for school safety must underst<strong>and</strong> <strong>and</strong> manage these risks, particularly those risks<br />
that threaten the lives <strong>of</strong> students, teachers, <strong>and</strong> staff. Earthquake risk is the product <strong>of</strong> hazard<br />
exposure <strong>and</strong> building vulnerability, as shown in the following equation: [5]<br />
RISK = HAZARD x VULNERABILITY x EXPOSURE
2. <strong>Seismic</strong> risk assessment Method<br />
The various methods for the assessment <strong>of</strong> the vulnerability <strong>of</strong> buildings differ in expenditure <strong>and</strong><br />
precision. The type <strong>of</strong> method chosen depends on the objective <strong>of</strong> the assessment but also on the<br />
availability <strong>of</strong> data <strong>and</strong> technology. The table 01 shows the Methods for the assessment <strong>of</strong> the<br />
vulnerability <strong>of</strong> buildings [7].<br />
Table 01: Methods for the assessment <strong>of</strong> the vulnerability <strong>of</strong> buildings<br />
Total 30 schools (more than 400 buildings) were instigated with rapid visual screening procedure.<br />
Since, Sri Lanka does not have local guidelines to do the visual screening; a novel screening format<br />
was developed in order to cope with local conditions. This paper will highlight the structural<br />
deviancies identified in the survey only. However, important details such as number <strong>of</strong> students, work<br />
force <strong>and</strong> previous disaster were recorded for further research purposes.<br />
3. Results <strong>and</strong> Discussion<br />
The type <strong>of</strong> building identified during the investigation procedure can be categorized as, concrete<br />
frame with unreinforced masonry infill walls, unreinforced masonry structures <strong>and</strong> etc. It is very<br />
interested to notice that, majority <strong>of</strong> the buildings (about 70%) are comprised with unreinforced<br />
masonry buildings with compared to reinforced concrete frame buildings that represent 29% <strong>of</strong> the<br />
total buildings. The figure 3 illustrates the information’s found during the survey in a format <strong>of</strong> pie<br />
chart. Other than that, most <strong>of</strong> the school buildings were constructed at the 10-20 years ago which is<br />
now in bad conditions. Even though some buildings are relatively new it is required to further stress<br />
that, these school buildings are vulnerable due to lack <strong>of</strong> maintenance; therefore some <strong>of</strong> them have<br />
changed its use to administrative <strong>of</strong>fice only. The typical buildings found during the visual<br />
observation procedure are shown in figures 4.
Figure 3: Classification <strong>of</strong> buildings according to type <strong>of</strong> construction<br />
Figure 4: Typical single storey <strong>and</strong> multistory buildings in school<br />
The deficiencies <strong>of</strong> the school buildings can be summarized under several topics. Firstly, some old<br />
school buildings are <strong>of</strong> only load bearing masonry without any seismic safety provisions. Therefore,<br />
the gravity load transfer is only through walls. Hence in the case <strong>of</strong> earthquake, the lateral load will be<br />
transferred through the elements which are masonry (fig.3). As a result <strong>of</strong> that, the wall could be<br />
cracked from the openings <strong>and</strong> may lead to collapse <strong>of</strong> building. In addition to that, in the reinforced<br />
concrete (RC) structures the efficiency <strong>of</strong> the RC system depends on its beam-column foundation<br />
interaction to transfer the lateral loads from earthquake. None <strong>of</strong> the school building has been design<br />
in order to with st<strong>and</strong> lateral loads. It is necessary to further stress that, the joint detailing requires<br />
special confinement to accomplished ductile mode <strong>of</strong> failure. The detailing have to be in such a way<br />
that, failure has to be occurring in the beam not in the column. On the other word, strong column-weal<br />
beam concept. The existing cracks in the main load bearing elements such as columns (fig.4) can be<br />
vulnerable during earthquakes. Since, the structure is already crack its load bearing capacity<br />
drastically goes down <strong>and</strong> building can fail due to its limited lateral load bearing capacity.
Figure 3: Brick columns in the building<br />
Figure 4: Failure <strong>of</strong> corner columns<br />
The irregular building configurations were observed in many <strong>of</strong> buildings. The “L” <strong>of</strong> the building in<br />
plan was the popular configuration in many <strong>of</strong> buildings. Due to its irregularity in plane it can<br />
undergo tensional mode <strong>of</strong> vibration during the earthquakes. Other than that, presences <strong>of</strong> short<br />
columns were observed at the most <strong>of</strong> the school buildings. In case <strong>of</strong> earthquake the short columns<br />
are liable to fail due to high stress concentrations (figure 5).<br />
Figure 5: Short columns in the buildings<br />
Despite <strong>of</strong> that, the foundation condition is one <strong>of</strong> important parameter to govern the seismic safety <strong>of</strong><br />
buildings. As the evidence found during the investigation procedure it can be conclude that the most<br />
<strong>of</strong> the buildings possess bad foundation conditions due to scouring. Since the ground condition is<br />
almost a s<strong>and</strong>y soil, the conditions can be vulnerable during the earthquake action.
Figure 6: Foundation conditions observed in the survey<br />
In addition to the main structural deficiencies, control <strong>of</strong> fire is very much important after an<br />
earthquake happen. As the evidence from the seismic survey it can be concluded that many <strong>of</strong> the<br />
buildings are with bad electric installation systems. Therefore, fire can be initiate <strong>and</strong> spread after<br />
disasters. The following figures show the typical wiring installation system in a school.<br />
Figure 7: Typical electric installation systems found during the survey<br />
The results obtain during the visual observation procedure show that a large number <strong>of</strong> school<br />
buildings are moderately or highly vulnerable to earthquake loading. The main defective identified<br />
during the study is poor structural conditions such as cracks, reinforced exposures, etc that consist <strong>of</strong><br />
68 % <strong>of</strong> total buildings. Other than that, 44 % <strong>of</strong> the building posses the week foundation conditions<br />
such as scouring <strong>and</strong> permanent damages due to various actives. In addition to that, the other<br />
structural defect is the short column problem which not only appears in old constructions but also in<br />
new buildings constructed with no technical assistance consists <strong>of</strong> 23 % <strong>of</strong> total buildings. S<strong>of</strong>t storey<br />
in buildings, structural irregularities were observed as other leading problems in the structural system<br />
<strong>of</strong> school buildings. The results <strong>of</strong> the structural classification with respect to type <strong>of</strong> defects are<br />
summarized in the figure 8.
Figure 8: Structural deficiencies as a percentage <strong>of</strong> totals<br />
4. Conclusion<br />
In this study total 30 school buildings (more than 400 buildings) were investigated with visual<br />
observation procedure. This methodology shown to be effective capturing the basic features <strong>of</strong> the<br />
school buildings for a rapid <strong>and</strong> economical assessment <strong>of</strong> the seismic vulnerability. From the basic<br />
structural types identified, the unreinforced masonry structures are dominant. Others consist <strong>of</strong><br />
reinforced concrete structures <strong>and</strong> wooden structures. It is very interested to notice that, not only old<br />
buildings but also newly constructed buildings posse’s structural deficiencies. Accordingly, it can be<br />
concluded that, majority <strong>of</strong> school buildings are posse’s structural deficiencies against seismic loading<br />
conditions. Therefore, it is recommended that, the school buildings need more attention prior to its<br />
construction as well as during maintain in order to overcome such vulnerable conditions.<br />
5. Reference<br />
http://studentlanka.com/alevel/government-schools/<br />
Pr<strong>of</strong> Abayakoon S.B.S., Journal <strong>of</strong> the geological society <strong>of</strong> Sri Lanka, vol 6 (1995/96) 65-72, Sri<br />
Lanka.<br />
http://www.preventionweb.net/files/3285_UNISDRAsiaPacificRegional2.pdf<br />
http://eusoils.jrc.ec.europa.eu/esdb_archive/eudasm/asia/lists/clk.htm<br />
Rapid Visual Screening <strong>of</strong> <strong>Buildings</strong> for Potential <strong>Seismic</strong> Hazards, FEMA 154, Edition2, March<br />
2002.
F. GU¨ LTEN GU¨ LAY, _IHSAN E. BAL, <strong>and</strong> TANSU GO¨ KC¸ E, Correlation Between Detailed<br />
<strong>and</strong> Preliminary <strong>Assessment</strong> Techniques in the Light <strong>of</strong> Real Damage States, Journal <strong>of</strong> Earthquake<br />
Engineering, 12(S2):129–139, 2008.<br />
Marie-José NOLLET, Karine LEFEBVRE <strong>and</strong> Omar CHAALLAL, STRUCTURAL<br />
CHARACTERISTICS OF HISTORICAL BUIDLINGS IN OLD MONTREAL, 13th World<br />
Conference on Earthquake Engineering, Vancouver, B.C., Canada ,August 1-6, 2004