Seismic Risk and Site Response Analysis for City of Bandung-Indonesia

Bandung is considered as a relatively earthquake prone region. Seismic risk analysis considering subduction zone and surrounding active strike-slip faults in the area was performed. Crouse and Joyner & Boore attenuation functions were adopted for the subduction and strike-slip faults, respectively. The analysis was performed employing total probability theorem using EQRISK program with modification on the attenuation functions. The analysis indicated that peak base-rock acceleration is 147 gal and 200 gal for 200 and 500 years return period, respectively. Local site effects were considered by performing site response analyses in the form of wave propagation analysis from base-rock to ground surface. The analyses were performed by considering variations in dynamic soil properties. Properties of the local ground are obtained from collected soil investigation report covering Bandung area especially for northward and southward area. The wave propagation analysis was performed by using SHAKE91 computer program. Various input motions consisting of scaled available strong motion records as well as synthetic time history that are considered reasonable for Bandung, it were employed in this analysis. Target spectra for Bandung considering subduction and strike-slip mechanism were developed and then it is used to generate synthetic time histories using SIMQKE program. Result of the analysis is presented in the form of peak ground surface acceleration and amplification factor contours at ground surface. In addition, site classification of southern and northern part of Bandung based on average shear wave velocity criteria was generated. The shear wave velocity for the sites was correlated from N-SPT obtained from soil boring data. Finally, response spectra for each site class covering important sites of Bandung area are presented along with recommendations on amplification factor and design response spectra. Result of the analysis was used as an input for damage estimates of buildings and lifelines for earthquake scenario as part of Risk Assessment Tools for Diagnostic of Urban Areas against Seismic Disaster (RADIUS) Project for earthquake disaster mitigation of the city. The design response spectra from this analysis are recommended for the new building codes of the city

Seismic microzonation of Semarang, Indonesia, based on probabilistic and deterministic combination analysis

One of the most important pieces of information obtained from the new Indonesian seismic hazard maps completed in 2017 was the identification of a fault that crosses the city of Semarang. This fault can be categorized as a new dangerous seismic source and should be taken into account in future seismic mitigation planning of this city. This paper describes the seismic microzonation of Semarang carried out via a combination of probabilistic and deterministic hazard analysis. The purpose of this research was to develop a risk map for Semarang based on one percent building collapse in 50 years. The analysis was performed using the same method employed in developing risk targeted Maximum Considered Earthquake (MCER) maps in 2012, with an improved beta (logarithmic standard deviation) value of 0.65 and adjusted direction factors of 1.1 and 1.3 for short- and long-period spectral acceleration, respectively. Whereas the 2012 maximum MCER spectral acceleration was distributed in the north-east of the study area due to the presence of Lasem fault, the 2018 maximum is located in the north-western part of the city as a result of the newly developed Semarang fault

ANALISIS POTENSI LIKUIFAKSI DENGAN PENDEKATAN PROBABILISTIK (PERFORMANCE-BASED EVALUATION) DI KOTA PADANG, SUMATERA BARAT

Evaluation of liquefaction potential by the conventional way are based on deterministic methods. The methods use only one condition of earthquake load as parameter in liquefaction analysis. Actually, the strength of earthquake loads are varies. In the other words, there is the uncertainty magnitude of earthquake loading. The uncertainty can be taken into analysis only by using a probabilistic approach. This study describes how to analyze liquefaction by probabilistic method. The method used was performance-based evaluation, developed byKramer and Mayfield (2005, 2007). This method include contributions from all levels of magnitude earthquake (hazard levels) in liquefaction analysis. The research location is in Padang, West Sumatra. Soil Investigation data used are N-SPT and shear wave velocity spread in the city of Padang. Earthquake load parameters used were obtained from PSHA and deagregation analysis. The results of this study show the variation of liquefaction potential across the city of Padang based on liquefaction return period. The location with great potentialfor liquefaction (FS <1) by the probability more than 50% were in the coastal region and northern parts of Padang

Development of Risk Coefficient for Input to New Indonesian Seismic Building Codes

In 2010 a national team (Team 9) developed the hazard curve and maximum considered earthquake (MCE) for the whole Indonesian area. The results were further applied in this study. Risk-targeted ground motions (RTGM) with 1% probability of building collapse in 50 years were developed by integrating the hazard curve with the structural capacity distribution. Parametric study on various variables that affect the log-normal standard deviation suggests a value of 0.7. In the effort to obtain the RTGM for the whole Indonesian region, integration was carried out using definite integration in which the curves are split into thin vertical strips and the areas below each curve are multiplied and summed. Detailed procedures and verification are given in this paper. An example of RTGM calculation was carried out for Jakarta City and then applied to the whole Indonesian region. Risk coefficients defining the ratio between RTGM and MCE were eventually developed and mapped. Risk coefficient development was generated for two periods of interest, i.e. a short time period (T = 0.2 seconds) and a 1-second period, respectively. Based on the results, for the period of 1.0 seconds 55% of Indonesian cities/districts have a risk coefficient in the range of 0.9 to 1.1 and about 37% in the range of 0.7 to 0.9, with only 5% in the range of 1.1 to 1.25

PEMILIHAN BENTUK MODEL PENILAIAN RISIKO BENCANA GEMPA BUMI UNTUK RUAS JALAN NASIONAL DI INDONESIA

Indonesia merupakan negara yang sangat rawan terhadap bencana alam. Bencana alam banjir, gempa bumi, longsor, gempa bumi, dan tsunami merupakan bencana alam yang banyak berpengaruh terhadap jalan dan jembatan di Indonesia. Gempa bumi merupakan bencana yang kejadiannya sulit diprediksi, tetapi dampak merusak gempa bumi sangat besar dibanding dengan bencana banjir yang selalu terjadi secara periodik. Pemerintah Indonesia belum memiliki manajemen risiko bencana alam yang menyeluruh untuk ruas jalan, terutama tahap mitigasi. Pada saat ini baru tersedia dan diterapkan pedoman untuk tahap tanggap darurat (setelah terjadi bencana). Pada saat ini telah berkembang model penilaian kuantitatif, kualitatif dan semi kuantitatif sebagai alat untuk menilai risiko bencana. Pemilihan bentuk model penilaian yang tepat sangat penting berkaitan dengan keluaran yang diharapkan. Masing-masing bentuk model penilaian memiliki kebutuhan masukan jumlah dan ketelitian/akurasi data. Penelitian ini bertujuan untuk memilih model penilaian risiko bencana gempa bumi untuk ruas jalan nasional. Metodologi yang digunakan adalah dengan studi literatur dan pengambilan data primer dengan wawancara. Hasil studi literatur dan pengamatan lapangan memperlihatkan bahwa model penilaian semi kuantitatif merupakan model yang paling cocok digunakan untuk Indonesi

Nonlinear Dynamic Analysis Adopting Effective Stress Approach of an Embankment Involving Liquefaction Potential

Stability of an embankment under earthquake loads is challenging in the process of analysis and design. Some embankment design consist of saturated granular material that is potential to liquefaction. Earthquake loads to the embankment under this conditions is one of major cause of embankment failure. Seismic performance involving stress-deformations and excess-pore-water pressure was evaluated in this paper. The evaluation adopts effective stress approach with non-linear elasto-plastic constitutive model. Numerical simulations through parametric studies were performed to estimate minimum density and embankment height efficiently to tolerate lateral displacements due to liquefaction. A number of parametric analyses were performed to investigate the relationships among relative densities of sand, ground accelerations, embankment height to excess-pore-pressure and lateral displacement of the embankment. The liquefaction analysis is conducted numerically using a finite difference method FLAC Dynamic 2D software adopting Finn-Byrne constitutive model

Assessment on earthquake resistance spectral design load criteria for buildings and infrastructures in Indonesia

General assessment on earthquake resistance spectral design load criteria for buildings and infrastructures associated with the recent development of Indonesian seismic hazard maps is presented in this paper. The assessment is directed toward general identification of their associated risks for input to policy formulation of disaster risk reduction management plans or strategies. Indonesian seismic hazard maps haveevolved for the last three decades. This is originated from an early development map before 2002, where a seismic hazard map particularly for buildings (1983) was developed adopting the early process of probabilisticseismic hazard analysis (PSHA) for 200 years return period (RP). Further, a 2002 version seismic hazard maphas been developed in the form of peak ground acceleration (PGA) for 500 years RP. Spectral design criteriafor buildings and bridges have been later developed by updating PSHA involving new seismic source zones, ground-motion predictive equations, and various earthquake RP, accommodating seismic codes for buildings(2500 years RP), for bridges (1000 years RP) and dams involving various RP up to 10,000 years RP correspond to its design level. The spectral accelerations also have included PGA, short (0.2s) period, and 1-s period. The latest update hazard maps (2017) have been developed and adopted for seismic codes for buildings, bridges, dams, and other related infrastructures. The increase in spectral design load criteria is identified to assess the general risk of existing constructions, considering the results of several recent building damage surveys. Adoption of new seismic codes based on the most recent hazard maps along with its enforcement is expected to contribute to seismic disaster risk reduction in Indonesia

Nonlinear Dynamic Analysis Adopting Effective Stress Approach of an Embankment Involving Liquefaction Potential

Stability of an embankment under earthquake loads is challenging in the process of analysis and design. Some embankment design consist of saturated granular material that is potential to liquefaction. Earthquake loads to the embankment under this conditions is one of major cause of embankment failure. Seismic performance involving stress-deformations and excess-pore-water pressure was evaluated in this paper. The evaluation adopts effective stress approach with non-linear elasto-plastic constitutive model. Numerical simulations through parametric studies were performed to estimate minimum density and embankment height efficiently to tolerate lateral displacements due to liquefaction. A number of parametric analyses were performed to investigate the relationships among relative densities of sand, ground accelerations, embankment height to excess-pore-pressure and lateral displacement of the embankment. The liquefaction analysis is conducted numerically using a finite difference method FLAC Dynamic 2D software adopting Finn-Byrne constitutive model

Site-Specific Response Analysis (SSRA) and pairs of ground- motions time-history generation of a site in Jakarta

The purpose of earthquake resistance design of building is to produce a structures that can withstand a certain level of a ground shaking without excessive damage. Careful consideration in the design of structures and facilities to the seismic are implemented by design of ground-motions. Jakarta as the capital city of Indonesia has potential of seismic hazard. Thus, design of high rise buildings in Jakarta requires reliable seismic design criteria for the safety and cost-effectiveness of the construction. Site-specific response analysis with reference to SNI-1726-2012 and generation of pairs of ground-motions with reference to FEMA-1050- 2015 of a proposed high-rise building site in Jakarta has been conducted. Through PSHA, two hazard levels of earthquake have been developed, that is representing 50% probability of exceedence (PE) in 30 years (43 years earthquake return period) and 2% PE in 50 years (2,475 years earthquake return period) ground-motions at reference base-rock (Sb). In addition, risk-targeted ground-motions (RTGM) defined as 1% probability of the building collapse in 50 years has been also developed adopting P-value = 0.65. Seven pairs of ground- motions time-history have been generated with spectral periods scaling from 0.2-10.0 sec considering seismic sources from Megathrsut, Beniof and Shallow Crustals have been applied to consider the short and long period motions have potential to hit the proposed building with structure period of 7.0 second

Hazard Deaggregation for Indonesia

Abstract. Hazard deaggregation is required in seismic hazard analysis in order to determine the controlling magnitudes and distances for particular return periods of earthquakes. These magnitude and distance are required for physical interpretation of the results from probabilistic seismic hazard analysis and to take certain engineering decisions. This paper presents a development of hazard deaggregation for Indonesia. The deaggregation process is started by calculating the ground shaking with hazard level 10% probability of exceedance in 50 years. In this study, the deaggregation hazard map was analyzed using total probability method and by applying three dimensional (3-D) source models and recent seismotectonic parameters. Three source models were used in this analysis, namely: subduction zones, transform fault zones and background source zone. Indonesian earthquake source models were constructed and published attenuation relations to calculate the peak ground acceleration for rock site conditions were used in the analysis. The recurrence rates and sizes of historical earthquakes on known and inferred faults and across zones were determined from modified earthquake catalog. The results of this study are deaggregation hazard maps of Indonesia for 10% probability of exceedance in 50 years.Abstract. Deagragasi hazard diperlukan dalam analisis seismic hazard untuk menentukan jarak dan magnitude kendali untuk perioda ulang gempa tertentu. Jarak dan magnitude ini digunakan untuk interpretasi fisik terhadap hasil dari analisis seismic hazard probabilistik dan untuk mengambil keputusan tentang hal yang bersifat keteknikan. Paper ini memberikan hal berupa pengembangan deagregasi hazard untuk Indonesia. Proses deagregasi dimulai dengan menghitung goncangan tanah dengan level hazard 10% probabilitas terlampaui dalam jangka waktu 50 tahun. Dalam studi ini, deagregasi hazard diananlisis menggunakan metoda probabilitas total dengan mengaplikasikan model sumber gempa tiga dimensi dan parameter seimotektonik terbaru. Tiga model sumber gempa digunakan dalam analisis ini yaitu sumber gempa zona subduksi, transform fault dan sumber background. Model sumber gempa Indonesia telah dikembangkan dan fungsi atenuasi yang terpublikasi digunakan untuk menghitung percepatan tanah puncak untuk kondisi site batuan. Ukuran dan laju keberulangan gempa-gempa histori pada fault yang sudah dikenal maupun fault yang keberadaanya masih dalam dugaan dan juga pada zona yang lain ditentukan dari katalog gempa yang telah dimodifikasi. Hasil dari studi ini adalah berupa peta deagregasi hazard untuk Indonesia dengan 10% probabilitas terlampaui dalam jangka waktu 50 tahu