POTENSI KERUSAKAN BANGUNAN BERTINGKAT SEDANG DENGAN SKENARIO GEMPA ≥ 5 SR SEBAGAI UPAYA MITIGASI BENCANA DI YOGYAKARTA
Abstract
Abstrak
Yogyakarta merupakan salah satu provinsi di Indonesia yang mempunyai tingkat aktivitas kegempaan tinggi. Sejarah mencatat bahwa Yogyakarta berulang kali mengalami kejadian gempa merusak. Salah satu upaya pemerintah guna meminimalisir risiko gempa yaitu dengan menerbitkan dan memperbaharui peta gempa setiap periode tertentu. Studi terbaru menunjukkan bahwa nilai akselerasi gempa di beberapa daerah mengalami peningkatan dibandingkan dengan percepatan gempa terbaru tahun 2017. Peningkatan nilai akselerasi gempa tersebut menimbulkan kekhawatiran terutama terhadap kondisi bangunan eksisting, oleh karena itu perlu dilakukan prediksi akurat tentang bagaimana potensi kerusakan bangunan eksisting terhadap gempa besar kemungkinan terjadi sebagai upaya mitigasi bencana. Studi ini menggunakan data gempa dengan magnitude ≥ 5 Mw dari rentang waktu tahun 1900 sampai 2020 dengan radius 500 km terhadap objek penelitian. Probabilistic seismic hazard analysis digunakan untuk mendapatkan respon spektrum gempa probabilitas 2% dalam 50 tahun. Pushover analysis dilakukan dengan memodelkan bangunan eksisting untuk mendapatkan kurva kapasitas. Performance point didapatkan dari pertemuan antara kurva kapasitas dengan response spektrum. Kurva kapasitas juga digunakan untuk menentukan median spectral displacement yang berfungsi dalam pembuatan fragility curve. Plotting antara performance point dengan fragility curve menghasilkan potensi kerusakan bangunan. Apabila gempa besar terjadi pada arah sumbu x potensi bangunan tidak mengalami kerusakan sama sekali sebesar 0,465%, rusak ringan 4,959%, sedang 45,940%, berat 37,880% dan hampir runtuh 10,756%. Sedangkan apabila gempa besar terjadi pada arah sumbu y potensi tidak terjadi kerusakan sama sekali yaitu 0,465%, rusak ringan 4,959%, sedang 45,940%, berat 37,880% dan hampir runtuh 10,756%. Potensi kerusakan bangunan akibat gempa besar didominasi oleh kerusakan sedang.
Kata kunci: Gempa, Probabilistic seismic hazard analysis, Pushover analysis, Fragility curve, Potensi kerusakan bangunan
Abstract
Yogyakarta is one of the provinces in Indonesia which has a high level of seismicty. Yogyakarta has experienced destructive earthquakes repeatedly. One of the government's efforts to minimize the risk of earthquakes is by publishing and updating earthquake maps provisionally. Recent studies have shown that the earthquake acceleration in several areas has increased compared to the acceleration of the latest map. This increase raises concerns, especially regarding to the existing buildings. As disaster mitigation effort, it is necessary to make accurate predictions about how potential damage of existing buildings is likely to occur. This study used earthquakes data with magnitude of ≥ 5 Mw from 1900 to 2020 with a radius of 500 km toward the building. Probabilistic seismic hazard analysis was used to obtain response spectrum of 2% probability in 50 years. Pushover analysis was performed by modeling the existing building to obtain capacity curve. Performance point was obtained from the meeting between capacity curve and response spectrum. Capacity curve was also used to determine the median spectral displacement to build fragility curve. The plotting results between performance point and fragility curve is building's damage potential. if a big earthquake occurs in the x-axis direction, the potential of no damage is 0.465%, slight 4.959%, moderate 45.940%, extensive 37.880% and nearly colapse 10.756%. Meanwhile, if a big earthquake occurs in the y-axis direction, Potential of no damage is 0.465%, slight 4.959%, moderate 45.940%, extensive 37.880% and 10.756% almost collapse. The building's damage potential is dominated by moderate.
Keywords: Earthquakes, Probabilistic seismic hazard analysis, Pushover analysis, Fragility curve, Building's damage potential
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DOI: http://dx.doi.org/10.29103/tj.v11i1.409
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