(PDF) A Simplified Method for Preliminary Seismic Vulnerability Assessment of Existing Building in Kundasang, Sabah, Malaysia

Jurnal Full paper Teknologi A Simplified Method for Preliminary Seismic Vulnerability Assessment of Existing Building in Kundasang, Sabah, Malaysia M.Ghafar, N. Ramly, M. Alel*, Azlan Adnan, Edy Tonnizam Mohamad, M.Z.M.Yunus Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor Malaysia *Corresponding author:

Article history Abstract Received: 17 August 2014 A simplified method for preliminary seismic vulnerability assessment of existing building in particular Received in revised form: area of Kundasang, Sabah Malaysia region is proposed. The surveys are mainly focused on building 17 November 2014 inventory such as identifying the building occupancy, building type and the storey number of buildings Accepted: 24 December 2014 for study area. Rapid Visual Screening (RVS) can be effectively used to evaluate the vulnerability of large number of buildings for study area with less computational effort. The data collection form of the Federal Emergency Management Agency (FEMA 154) for RVS was gathered for this purpose. The Graphical abstract objective of this study is to assess the vulnerable building that tendency to be further detailed analysis by the calculation of score in RVS method. Pre-assessment towards seismic vulnerability of every individual building in particular area has been assessed and the information of buildings in study region consist residential, industrial, government, school building occupancies were recorded and spatially analyzed using Geographical Information System (GIS) framework. Buildings in Kundasang are considered as less further evaluation (34%) which need have detailed analysis by modeling the structure, while another 66% considered as safe building based on rapid visual final score. Keywords: Vulnerability assessment, Rapid Visual Screening, GIS. Abstrak Satu kaedah mudah bagi pra-penilaian seismik bangunan di kawasan tertentu wilayah Kundasang, Sabah, No of Buildings againts Building Type 400 353 Malaysia.. Kaedah tinjauan ini terutamanya tertumpu kepada membina inventori bangunan seperti 350 mengenal pasti penghunian bangunan, jenis bangunan dan bilangan tingkat bangunan bagi kawasan 300 kajian. Pemeriksaan Visual Pesat (RVS) boleh digunakan dengan berkesan bagi menilai kelemahan 250 sebilangan besar bangunan bagi kawasan tertentu dengan kaedah yang kurang pengiraan. Objektif kajian 200 ini adalah untuk menilai bangunan berpontesnsi kecenderungan untuk dianalisis lebih terperinci dengan 150 143 pengiraan skor dalam kaedah RVS . Bangunan di Kundasang dianggap sebagai kurang (34% ) yang 79 memerlukan analisis terperinci oleh pemodelan struktur, manakala selebihnya lagi dianggap bangunan 100 44 54 44 selamat 66 % berdasarkan faktor oleh seni bina. Semua pangkalan data bangunan direkodkan dan 50 dianalisis dengan menggunakan Sistem Maklumat Geografi rangka kerja (GIS). 0 C3 W1 W2 S3 URM RM1 Building Type Kata Kunci: Kelemahan bangunan, Penilaian Visual Rapid (RVS), GIS. © 2015 Penerbit UTM Press. All rights reserved. 1.0 INTRODUCTION longitude 116˚ 45’E, 16 km Northeast of Ranau, Sabah. Tremors felt near Ranau, Sabah. Most people perceive that Malaysia has been categorized under low seismicity area. Malaysia is free from life-threatening seismic crisis. In reality, Consequently, earthquake resistant design has not been given seismic hazard in Malaysia is irrefutable, with seismic hazard as emphasis until a decade ago when the Malaysian originating from seismically active neigbouring countries lawmakers were briefed by Meteorological Department such as Indonesia and Philippines [2]. (MMD), in 2002, on the distant of shock waves of the 2001 In the past, Kundasang region has been jolted by Gujarat earthquake, which travelled 600 km from its epicenter moderate earthquake events as reported in MMD database. to rock and cause devastation to many cities in India [1]. The study area is located at Kundasang, Sabah, Malaysia. It Since 2005, the government of Malaysia has taken various lies from latitude 5˚ 58’ N to 6˚ 00’ and longitude from 116˚ efforts, through the Ministry of Science, Technology and 33’ E to 116˚ 36’E and the covered area about 22.2 km. Innovation (MOSTI), to assess the risk associated with Kundasang owes its moderate seismicity condition to the potential earthquake events. A report from MMD, a weak active Mensaban and Lobou-Loubo faults zones, which have earthquake has occurred with magnitude 4.8 Richter scale in brought about earthquake that cause light damages to Pekan Ranau, Sabah at 7:35pm on 01 February 2014.The infrastructures such as road and bridge [3]. This region has earthquake epicenter is located at latitude 6˚10’ N and been identified as a potential site for a future catastrophic earthquake and has already witnessed seismic events of lower 72:3 (2015) 1–7 | www.jurnalteknologi.utm.my | eISSN 2180–3722 | 2 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 magnitude in recent past. These earthquakes have demonstrates that the seismic vulnerability of the building stocks in the region was primarily responsible for a large number of human casualties [4]. Most of the buildings in the region are non-engineered and awareness and knowledge among the masses is lacking regarding earthquake-resistant construction technique in areas of high seismic vulnerability. Inadequate building by law and lenient regulatory regimes only contribute to the problems. There is a need to assess the vulnerability of building stocks in such seismically active area. Due to non-availability of enough building inventory data for seismic vulnerability assessment, a procedure based on fieldwork called Rapid Visual Screening (RVS) is found to be suitable and has been illustrates using Geographical Information System (GIS) in term of building occupancy [5]. Vulnerability is often represented by the probability of reaching or exceeding different damage state for a specified hazard scenario. Vulnerability can be briefly defined as ‘being prone to or susceptible to damage or injury’ [6]. To determine vulnerability, a long chain of causes or factors can be analyzed, and among them, natural, technological, social and political are the salient factors. The assessment of vulnerability to estimate the seismic risk requires particular information on each one of the factors and elements at risk. All items, like geologic evolution, urban development, strength of structures and possible collateral effects, have to be considered carefully to assess as accurately as possible the seismic vulnerability of a site. Seismic vulnerability can be measured either qualitatively or quantitatively [7]. The qualitative measure of assessment can be carried out by classification of damages to various types of constructions using different earthquake intensity scales Modified Mercalli Index (MMI). Another way of making qualitative measures of vulnerability is in terms of damage states [8]. A specified ward in Kundasang (Figure 1) was developed as boundary of study. The inventory data needed for vulnerability assessment of houses and buildings in study ward were gathered using simplified form, in order to carry out an extensive survey. Figure 1 Buildings, main roads and side roads in study ward. 2.0 METHODOLOGY 2.1 Building Inventory Building Inventory was conducted during the fieldwork. These include residential, commercial, industrial, religious, government, emergency, history and education as building occupancy data. The limitation on building inventory was carried out only for particular area in Kundasang. Figure 2 shows example of buildings in Kundasang in term of building occupancy. The data collection was prepared taking into consideration of five (4) main types of construction practice within the ward which are Reinforced Concrete (RC), brick, wood (Wood for housing,W1 and Wood For Commercial use, W2) and steel (Steel Frame Building,S3) as shown in Table 1. Figure 3 illustrates the information such are occupancy classes (Residential) and structure type (W1) required in the rapid visual form in order to assess vulnerable buildings in study area. Building databases are stored in Geographical Information System (GIS) framework. GIS integrates extremely diverse data and various tool into common framework for analysis, cooperation and decision making [9]. The development of GIS system involves detailed information that facilitates disaster preparedness, mitigation, rehabilitation and reconstruction or even rescues operations [10]. 3 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 Detailed seismic vulnerability evaluation is a technically complex procedure and can only be performed on a limited number of buildings. Thus, it is very important to use simplified procedure that can help to rapidly evaluate the vulnerability profile of different types of buildings, so that the more complex evaluation procedures can be limited to the most critical buildings [12] To assess the buildings within the surveyed area, the RVS method as suggested by Federal Emergency Management Agency is used [13]. Figure 2 Building occupancy in study ward area in Kundasang, Sabah. Residential (top left), Education (top right), Government (down left) and Religious (down right). SCREENER Table 1 Description of building types in Kundasang (a) Category Building Description Type Reinforcement C3 Concrete Frame Concrete (RC) Brick RM1 Reinforcement Masonry URM Unreinforcement Wood W1 Wood for housing W2 Wood for commercial Steel S3 Steel Frame 1.2 (b) Figure 4 Moderate seismicity FEMA 154 form (a) Basic Score Modifier for rapid visual screening (b). [14] Basic Structural hazard scores for various building types are provided in the RVS form. Figure 4(b) demonstrates the screener modifies the basic structural hazard score by identifying and circling score modifiers which are then added (or subtracted) to the basic structural hazard score to arrive at a final structural score, S. The basic structural hazard score, score Figure 3 Buildings identity in Kundasang ward modifiers and the final structural score S, are all related to the probability of building collapse [15]. The result of the screening 2.2 Rapid Visual Screening (RVS) procedure is a final score that may range above the basic score, with a high score indicating good expected seismic performance The Rapid Visual Screening (RVS) method was designed to be and a low score indicating a potentially hazardous structure. applied without performing any structural calculations. The While the score is related to the estimated probability of major procedure utilizes scoring systems that require the trained damage, it is not intended to be a final engineering judgment of evaluator. The inspection, data collection and decision making the building, but merely to identify buildings that may be processes typically occurs at the building site. The total duration hazardous and require detailed seismic evaluation. If the score is for the processes was expected to take approximately 20 minutes 2 or less, a detailed evaluation is recommended. On the basis of for each building based on numerical seismic hazard and detailed evaluation of engineering analysis through detailed vulnerability score [11]. procedures, final determination of seismic adequacy for rehabilitations can be made. 4 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 3.0 RESULTS AND DISCUSSION 571 3.1 Building Occupancy 515 600 The areas covered under the survey are located in Kundasang region. The survey was mainly focused on identifying building classification, building type, plot size and shape, clear distances Fieldwork F I 500 from surrounding structures and basic information of the building. Digital photographs of each building from at least two Fieldwork F II 257 directions were taken. A database was compiled in 400 Geographical Information System (GIS) attribute table. There Fieldwork F III are approximately 717 structures in the surveyed areas of Kundasang which differ in term of the type of buildings, 84 300 occupancy of buildings and number of storey. 84 75 3 24 200 2 24 3 24 19 19 19 Residential 3 Commercial 3 5 100 3 Industrial 5 8 Educational 5 6 Government 0 0 Religious History Fieldwork F III Emergency Fieldwork F II Fieldwork F I Figure 7 The numbers of building against Building Occupancy based on fieldwork. Figure 5 shows the building occupancy in study ward regarding on latest field work (F III). All the information provided are illustrated and managed in Geographical Information System (GIS) attribute table. Figure 6 shows the building occupancy in Figure 5 Building Occupancy based on Field work III. study ward regarding on latest field work (F III). All the information provided are illustrated and managed in GIS attribute table. The bar chart shown in Figure 7 illustrates the total number of buildings in term of building occupancy respectively. Based on bar chart, the highest number of buildings are in term of occupancy are the residential building (571) followed by commercial buildings. This is because Kundasang is categorized as rural area which has tourism and agriculture as main attraction. Figure 8 shows the relation between numbers of buildings with building types (such as C3, W1, W2 S3, URM and RM1) and W1 type is the majority in Kundasang. The figure indicates that most of Kundasang areas are populated with villagers while other types of buildings such as C3 are comprised mainly of school buildings, hotels and government buildings. No of Buildings againts Building 400 353 Type 350 300 Figure 6 Building Type based on Field Work III. 250 200 143 150 100 79 44 54 44 50 0 C3 W1 W2 S3 URM RM1 Building Type Figure 8 The numbers of building against building type. 5 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 Figure 9 illustrates the number of buildings according to the that need further investigation, for which based on Table 10, the number of storey. About 711 (99.2%) of buildings in total structural score less than 2 (S< 2) in Kundasang area is Kundasang are categorized as low rise, 5 (0.7%) are mid-rise lower (34%) than no need further investigation which is 66% buildings of 4-6 storey while only 1 (0.1%) equal or exceed 7 that score exceeding 2.5 (S>2.5). Figure 11(a) provides the storeys. number and percentage of hazardous and non-hazardous in study area respectively while figure 11(b) shows the composition of the hazardous buildings. About 183 (75.6%) Distribution according to Number considered hazardous buildings which is influenced by close of Storey proximity to the hill sides followed by commercial buildings 800 (33, 13.6%), education buildings (10, 4.13%), government 700 711 buildings (5, 2.1%), emergency buildings (6, 2.5%), History buildings (4, 1.7%), Industrial buildings (1, 0.4%), Religious 600 buildings (0, 0%) 500 400 300 200 100 5 1 0 1-3 4-6 ≥7 . Figure 9 Relation Between number of buildings and number of storey. 3.2 Rapid Visual Screening Score Sheet, Analysis and Uses The damage potential can be estimated based on Rapid Visual Screening (RVS) score as given in Table 2. However, it should be realized that the actual damage will depend on a number factors that are not include in RVS procedure. As a result, this table should only be used as indicative to determine the necessity of carrying out simplified vulnerability assessment of buildings. Table 2 Structural Scores with Damage Potential RVS Score Damage Potential High probability of Grade 5 damage; Very high probability S < 0.3 of Grade 4 damage High probability of Grade 4 damage; Very high probability 0.3 < S < 0.7 of Grade 3 damage High probability of Grade 3 damage; Very high probability 0.7 < S < 2.0 of Grade 2 damage High probability of Grade 2 damage; Very high probability 2.0 < S < 2.5 of Grade 1 damage S > 2.5 Probability of Grade 1 damage Table 3 shows the result of RVS based on type of building in Kundasang. Most of the buildings in Kundasang are of the residential type (571, 79.6%), out of which 183 (32%) are hazardous while 388 (68%) are non-hazardous. This is followed by commercial type (84, 11.7%), out of which 33 (39.3%) are hazardous while 51 (60.7%) are considered non- hazardous. Both the residential type and commercial type which are considered hazardous have a similar characteristic both in that have vertical irregularities in term of shape. History type of buildings (6, 75%) shown highest percentage out of which 4 (80%) are hazardous while 1 (20%) considered non-hazardous. This is because most of the buildings are built with weathered unreinforced masonry. Figure 10 demonstrates the RVS result using GIS based tool to locate the building which require further investigation. The result obtained from RVS shows the location of buildings 6 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 Table 3 Cumulative results of buildings from rapid visual screening Building Occupancy Number of Buildings Percentage Buildings per Area Number of Detailed Evaluation Buildings (%) YES NO (Hazardous) (Non- Hazardous) Residential 571 79.6 183 388 Commercial 84 11.7 33 51 Educational 24 3.3 10 14 Government 19 2.6 5 14 Emergency 8 1.1 6 2 History 5 0.7 4 1 Industrial 3 0.4 1 2 Religious 3 0.4 0 3 TOTAL 717 100 242 475 Figure 10 Map of buildings detailed evaluation based on RVS. 1 YES (Hazardous) 4 Number of 5 10 Detailed 6 Evaluation Residential Buildings YES Commercial (Hazardous) 33 242, 34% Educational 475, 66% Government Number of 183 Emergency Detailed Evaluation History Buildings NO (Non-Hazardous) Industrial (a) (b) Figure 11 Number and percentage of hazardous and non-hazardous building respectively (a) Composition of the hazardous building in Kundasang (b) 7 M.Ghafar et al. / Jurnal Teknologi (Sciences & Engineering) 72:3 (2015) 1–7 4.0 CONCLUSION AND RECOMMENDATION [2] Adnan, A.,Hendriyawan, A. 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