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PENGURANGAN RISIKO BENCANA ALAM GEMPA BUMI SEBAGAI UPAYA UNTUK MELAKSANAKAN RISK-BASED EARLY WARNING Widodo Pawirodikromo
TEKNISIA Vol. XX, No. 1, Mei 2015
Publisher : Jurusan Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indonesia

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The occurrence of natural hazards and disasters in general can not be avoided, and accordingly, the best way to overcome is to carry out an effective disaster management. The disaster management cycle has been defined and understood clearly.One of the main problem especially in the earthquake occurrence is the method of early warning. Semi quantitative investigation on the earthquake occurrences particularly at Yogyakarta province has been conducted. The relationship between earthquake occurrence and an effective early warning became the main discussion. The data of earthquake occurrence at Yogyakarta provinve in general is still relatively limited. The only available data was started at 1960’s and therefore for the purpose of earthquake forecasting and prediction, the numbers/completeness of the data should be improved. Result of the investigation showed that the concept of early warning system will be more comprehensive if it be conducted by using the principle of Risk-Based Early Warning. Reducing the disaster fatalities can be done not only by carrying out an early warning immediately before hazard but also can be extended inclusively in the disaster risk reduction program. Based on preliminary investigation and experiences, the structural damage at Yogukarata province would be occur if the shallow earthquake magnitude M is greater than 5.3 with the epicenter distance approximately less than 40 km. There are several earthquake prediction methods that have been developed by researchers, and one of them is strange animal behavior before earthquake. The strange animal behaviors were occurred before the Yogyakarta 27 May 2006 earthquake. This method can be used for the earthquake early warning in the future when it has been verified successfully.

ANALISIS HAZARD GEMPA DKI JAKARTA METODE PROBABILISTIK DENGAN PEMODELAN SUMBER GEMPA 3 DIMENSI Yunalia Muntafi; Widodo Pawirodikromo; Lalu Makrup
TEKNISIA Vol. XX, No. 2, November 2015
Publisher : Jurusan Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indonesia

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History records that Jakarta as the capital of Indonesia ever rocked by a devastating earthquake in 1699, 1780, 1883 and 1903, resulting in loss of physical, mental and material. The existence of several active faults around Jakarta potentially be the source of the earthquake that shook Jakarta. Therefore, the analysis of seismic hazard for Jakarta area is needed. The study was conducted by the method of Probabilistic Seismic Hazard Analysis (PSHA) with 3D modeling of seismic source and latest attenuation equations (Next Generation Attenuation) in accordance with the method used in the manufacture of the latest earthquake map (Earthquake Hazard Map of Indonesia 2010). The aims of this research are to (1) conduct hazard analysis seismic probabilistic as a reference value of the intensity of the hazard seismicity, (2) analyze deagragasi as early determinant of modification recording time history seismic acceleration corresponding to Jakarta bedrock and (3) analyze the spectral matching which then carried the ground motion design for Jakarta. The results of seismic hazard analysis shows that maximum acceleration at bedrock (PGA) for the Jakarta area with 500-year return period amounted to 0.236 g still in the range of PGA Jakarta by Indonesian Earthquake Hazard Map of latest ISO 1726-2012 (0.20g-0.25g). This value is close to the value of the Hutapea’s research results (2009), amounting to 0.239g. However, it is higher than the proposed PGA of Irsyam et al (2008) which amounted to 0.20g, and lower than the value of PGA on Indonesian earthquake map published by the USGS in which Jakarta was in the range of 0.245g - 0.326g. Based on the deagregation analysis, obtained two sets of real-time earthquake data, namely time history of Kocaeli earthquake in 1999 and Landers earthquake in 1992 to present megathrust and shallow crustal earthquake source, then by spectral matching analysis, obtained two synthetic ground motions for each seismic source mechanisms in the period of 0.2 sec and 1.0 sec for Jakarta.

ANALISIS POTENSI LIKUIFAKSI PADA PASIR VULKANIK DI PANTAI GLAGAH KULONPROGO BERDASARKAN DATA N-SPT Hanindya Kusuma Artati; Widodo Pawirodikromo; Edy Purwanto
TEKNISIA Vol. XXV, No. 2, November 2020
Publisher : Jurusan Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/teknisia.vol25.iss2.art6

One of the most causes of damage to structures during earthquake is a liquefaction. Liquefaction happened in a loose sand which saturated under earthquake shaking. Earthquake shaking will cause cyclic loading to the surface of the ground which potential for occurrence of liquefaction. The liquefaction phenomenon is a soil behavior under cyclic loads that occurs in just a few moments. Due to the short cyclic load, the soil mass suddenly changes from a solid limit to a liquid limit or has a main consistency such as liquid. Liquefaction events during an earthquake can be characterized by the presence of ground movement in the horizontal direction, seepage water out from fracture of the ground, movement of sloping or descending buildings, displacement of ground advance, and landslides. This study took a case study in Glagah Beach at Kulonprogo Regency. That is beach areas which is a landform alongside a body water which consist of loose particles such as sand where Yogyakarta International Airport (YIA) is located. Analysis was carried out to determine the potential of liquefaction based N-SPT data using the Seed, Martin & Lysmer (1975). Based on these data, The Cyclic Stress Ratio (CSR) value is calculated, which is the ratio between the average shear stress caused by the earthquake with the effective vertical stress in each layer and the value of the Cyclic Resistance Ratio (CRR), which is the amount of soil resistance to liquefaction. The analysis in the Kulonprogo Regency area is an area that is considered to require liquefaction. Analysis of liquefaction potential based on on N-SPT data with the Seed, Martin & Lysmer (1975) method on a 6,3 magnitude earthquake. The Result indicate the potential for liquefaction occurs up to a depth of 8,5 meters.

RASIO KEKAKUAN LENTUR (FLEXURAL STIFFNESS RATIO) ELEMEN BETON AKIBAT GEMPA BERDASARKAN ANALISIS DINAMIK STRUKTUR SINGLE DEGREE OF FREEDOM (SDOF) Widodo Pawirodikromo; Anggit Mas Arifudin; Dewi Ayu Harjani
TEKNISIA Vol. XXVI, No. 2, November 2021
Publisher : Jurusan Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/teknisia.vol26.iss2.art6

Modeling the effective stiffness of reinforced concrete elements for structural analysis is an important problem and needs to be solved. The effective stiffness is then expressed in terms of the average flexural stiffness ratio Ck. whose value has been determined by Codes. Previous studies have shown that the stiffness ratio is assumed/stated to be strength-dependent. Based on this statement, research on the flexural stiffness ratio Ck of reinforced concrete elements through dynamic analysis of the SDOF structure was carried out. The SDOF structural model used has a vibration period T = 0.48 sec. The dynamic load used is 50 earthquake records consisting of 3-groups of frequency content (low, moderate, high). The dynamic analysis that was carried out has accommodated the inelastic responses whose behavior follows Modified Takeda hysteretic loops. The study results showed that the maximum response of the structure generally occurred in the strong middle part of the earthquake recording or the period of the effective duration of D595. The main finding in this study is that the strength dependent of flexural stiffness is proven. The relationship between the average flexural stiffness ratio Ck and peak ground acceleration of PGA can be mathematically expressed in the equation Ck = -0.981.PGA + 0.822. The relationship is negative, meaning that the higher the PGA value, the smaller the Ck value with a correlation coefficient of R = 0.635 (moderate correlation). The Ck value negatively correlates with the drift ratio and damage index, DI.

Eksplorasi Rekaman Gempa-gempa di Indonesia dan Karakteristik Diri yang Dinyatakan dalam Acceleration Based Seismic Intensity Measures (SIMs) Widodo Pawirodikromo; Astriana Hardawati
TEKNISIA Vol 27 No 1 (2022): Teknisia
Publisher : Jurusan Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20885/teknisia.vol27.iss1.art5

Indonesia is a prone country to earthquake hazards. This situation is indicated by the number of earthquakes ranging from small to significant events. However, digital earthquake ground motion data are not available, making it difficult for further research. This paper aims to explore recordings of earthquakes that occurred in Indonesia, which are then presented in digital data and used to identify their damage potential in the form of Seismic Intensity Measures (SIMs). After being traced, it turned out that there were only six earthquakes whose ground acceleration time history was found through the paPers published by researchers. The earthquakes were the Mw 6.2 Yogyakarta (2006), the Mw7.6 Padang (2009), the Mw6.1 Bener Meriah Central Aceh (2013), and the Mw6.5 Pidie Jaya Aceh (2016), the Mw7.5 Palu (2018) and the Mw6.1 Malang (2021) earthquakes. The manual digitization and processing to obtain ground acceleration data every 0.01s time step are required. Eight aspects based on acceleration and two aspects based on response spectrum have been used as parameters for Seismic Intensity Measures SIMs. The exploration results show that the source of the earthquake in Sumatra is still relatively shallow, getting more profound in the Java and Nusa Tenggara subduction. The P.G.A. of the Yogyakarta earthquake is 0.272g with a total duration of more than 50 seconds. In general, according to SNI 1726, 2019, the spectrum has been able to cover all ground acceleration time histories. The Yogyakarta earthquake has the highest Earthquake Power, Arias Intensity, and Potential Destructiveness values, namely PE = 0.255 and IA = 2.201, and P.D. = 0.166.

Perbandingan Peta Percepatan Tanah di Permukaan sebagai Dasar Perencanaan Tata Ruang Berbasis Mitigasi Bencana di Provinsi Riau Elvis Saputra; Fitri Nugraheni; Widodo Pawirodikromo; Lalu Makrup
MEDIA KOMUNIKASI TEKNIK SIPIL Volume 27, Nomor 2, DESEMBER 2021
Publisher : Department of Civil Engineering, Diponegoro University

Spatial planning has an important role in disaster mitigation efforts. The availability of earthquake maps is very useful in spatial planning. The need for spatial planning today is micro spatial planning. Therefore, the 2017 national earthquake map needs to be detailed into a micro zonation map at the district or city scale. The ground acceleration presented in the national earthquake map was the acceleration at bedrock, while in spatial planning it is the necessary acceleration at the surface. Therefore, the purpose of this research was to obtain a map of the earthquake at the surface with a micro-scale. Determination of the acceleration value at the surface was carried out by two models. Model-1, the surface acceleration was obtained by multiplying the results of the PSHA analysis at bedrock by the amplification factor based on SNI-1726. While Model-2, the acceleration value at the surface was directly obtained from the results of PSHA analysis using the average surface shear wave velocity (Vs30) based on data from the USGS. The result of this study showed that from the 2 analytical models used, Model-2 has a higher surface acceleration value than Model-1. Riau Province has 12 districts. in general, the 12 districts were included in the low to moderate risk index class, but there was one district that was close to the high index class, namely Rokan Hulu district.

Studi Variasi Perletakan Pada Respon Seismik Bangunan 17 Lantai Pranowo Rahayu; Widodo Pawirodikromo
Konstruksia Vol 14, No 2 (2023): Jurnal Konstruksia Vol 14 No. 2 Tahun 2023
Publisher : Universitas Muhammadiyah Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24853/jk.14.2.119-127

Desain dan analisis bangunan tinggi yang dikenakan beban lateral gempa sangat penting pada daerah yang rawan potensi terjadinya gempa bumi. Pada desain struktur tahan gempa, respons struktur tidak dapat dihitung secara pasti, kecuali metode penyaluran beban dari tanah ke struktur telah ditentukan. Pada saat ini, asumsi yang sering digunakan, ialah kuat getaran bebas dapat diaplikasikan langsung pada dasar bangunan. Struktur diasumsikan terjepit kaku sempurna atau tak terhingga pada dasar pondasi. Asumsi ini diambil pada analisis MDOF. Kondisi tanah pada jenis tanah bisa lunak atau kaku, tetapi tidak kaku tak terhingga. Struktur gedung yang berada diatas tanah yang dikenakan gaya gravitasi tidak diperuntukan menahan dari terjadinya rotasi pada pondasi. Analisis respon yang lebih akurat dapat dicapai ketika tanah dimodelkan sebagai material yang fleksibel dan tidak diasumsikan sebagai material yang kaku tak terhingga.

Time History Sintetik di Wilayah Bogor Ditinjau dari Deagregasi Hazard Pranowo Rahayu; Widodo Pawirodikromo
Konstruksia Vol 14, No 2 (2023): Jurnal Konstruksia Vol 14 No. 2 Tahun 2023
Publisher : Universitas Muhammadiyah Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24853/jk.14.2.93-108

Indonesia dikenal selain sebagai negeri yang dikeliling cincin gunung api, juga wilayah yang paling kerap diguncang gempa. Salah satu, yang terdahsyat di zaman modern ini, adalah gempa yang menyebabkan tsunami Aceh 2004 yang memiliki kekuatan 9,1 â€“ 9,3Â Mw juga termasuk gempa besar di dunia. Salah satu gempa besar lain adalah gempa Cianjur 2022 yang berkekuatan 5,6 Mw. Salah satu cara yang dilakukan untuk mengurangi risiko gempa adalah mendesain bangunan dengan konsep tahan gempa. Dalam perencanaan bangunan dengan konsep tahan gempa terutama gedung tinggi dibutuhkan data time history dalam merencanakan beban gempa. ketersediaan data time history di Indonesia saat ini masih menjadi kendala. Tujuan dilakukannya penelitian ini adalah untuk menganalisis Bangunan Tinggi di Wilayah Bogor yang dapat jadikan referensi dalam mendesain beban gempa untuk perencanaan gedung. Penentuan Uniform Hazard Spectrum (UHS) dilakukan dengan metode probabilistik, kemudian dilanjutkan dengan melakukan spectral matching untuk mendapatkan ground motion sintetik, lalu tahap berikutnya menggunakan Deepsoil untuk mengetahui Shear Stress Ratio dan Tripartite Graph. Hasil dari penelitian ini diperoleh risiko gempa yang direpresentasikan dalam bentuk nilai percepatan untuk Wilayah Bogor pada UHS memiliki nilai percepatan T = 0 detik adalah 0.3537 g, T = 0.2 detik adalah 0.8689 g, dan T = 1 detik adalah 0.2802 g. Sumber gempa Sesar Cimandiri mendominasi sebesar 23,775% yang diprediksi memiliki kontribusi terbesar terhadap risiko gempa. Hasil Spectral Matching dengan Big Bear 01 1992 Wrightwood - Swarthout yang mempunyai magnitude 6.46 dengan mekanisme strike slip dan jarak 70.94 km yang kurang lebih sama dengan Deagregasi Hazard yang dimaksud. Hasil respons spektra memperlihatkan bahwa hasil dari matching begitu tinggi dan turun bertemu dengan respons spektra yang ada pada layer 1, 2, dan 3 di detik ke sekitar 0.74.

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