I Wayan Sengara, I Wayan
Center for Disaster Mitigation, Institute of Technology Bandung, Jl. Ganesa 10 Bandung, Indonesia.

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Development of Risk Coefficient for Input to New Indonesian Seismic Building Codes Sengara, I Wayan; Sidhi, Indra Djati; Mulia, Andri; Asrurifak, Muhammad; Hutabarat, Daniel
Journal of Engineering and Technological Sciences Vol 48, No 1 (2016)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (422.08 KB) | DOI: 10.5614/j.eng.technol.sci.2016.48.1.5

Abstract

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.
Hazard Deaggregation for Indonesia Makrup, L.L.; Irsyam, Masyhur; Sengara, I Wayan; Hendriyawan, Hendriyawan
Jurnal Teknik Sipil Vol 17, No 3 (2010)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (472.955 KB)

Abstract

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 tahun
Kajian Pemilihan Koefisien Situs pada Perhitungan Spektra Percepatan Gerakan Tanah di Permukaan Partono, Windu; Irsyam, Masyhur; Sengara, I Wayan; Asrurifak, Muhammad
MEDIA KOMUNIKASI TEKNIK SIPIL Volume 25, Nomor 1, JULI 2019
Publisher : Department of Civil Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (739.358 KB) | DOI: 10.14710/mkts.v25i1.22962

Abstract

SNI 1726:2012 states that surface spectral accelerations SMS (0.2 second) and SM1 (1 second) can be calculated by multiplying site factors Fa (0.2 second) and Fv (1 second) with spectral accelerations SS (0.2 second) dan S1 (1 second). All site factors used by SNI 1726:2012 are adopted from ASCE/SEI 7-10.  In 2013 Stewart and Seyhan proposed new and different site factors compared to ASCE/SEI 7-10. These site factors are then used for developing ASCE/SEI 7-16 with minor improvement for site class SE (soft soil). ASCE/SEI 7-16 states that the site factors for site class SE with SS greater than 1g or S1 greater than 0.2g, shall be calculated using Site Specific Analysis (SSA). The SSA method used for calculating site factor is difficult for ASCE/SEI 7-16 to be implemented in Indonesia. This paper describes the result of SMS and SM1 study at five cities (Jakarta, Bandung, Semarang, Yogyakarta and Surabaya) for site class SC, SD and SE using site factors proposed by Stewart and Seyhan and site factor SNI 1726:2012. The SMS and SM1 at five cities calculated using site factors proposed by Stewart and Seyhan are ±15% differences compared to SMS and SM1 calculated usingSNI 1726:2012 site factors.
Box Station Parametric Study with Time History Dynamic Analysis Sengara, I Wayan; Basarah, Yuamar I.; Sulaiman, Ahmad; Sibagariang, Sarah M.T.
Journal of Engineering and Technological Sciences Vol. 56 No. 3 (2024)
Publisher : Directorate for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2024.56.3.6

Abstract

The performance of an underground station structure subjected to an earthquake can be evaluated by looking at deformation as well as forces and bending moments that occur in the structure. Most design practices adopt simplified approaches, such as the free field deformation method and pseudo-static approaches, which have a high level of uncertainty. Therefore, it is necessary to perform dynamic time-history analysis to verify the results of the simplified approach. Dynamic modeling is considered a more appropriate approach because it better represents seismic shaking in evaluating the seismic response of underground structures. This study performed time-history dynamic analysis by conducting a parametric study. The study was conducted to determine the effect of parameters such as site class, peak base acceleration (PBA) ground-motion intensity, and the type of seismic mechanism on the deformation response. Based on the parametric study, it was found that the stiffer the site class, the smaller the relative deformation of the resulting underground structure. The greater the PBA intensity value, the greater the relative deformation. Relative deformation in the wall structure subjected to a subduction earthquake is more significant compared to that of a shallow crustal earthquake.