Electronic Theses and Dissertation

KAJIAN RESPON GEMPA DAN KERENTANAN BANGUNAN PUBLIK BERDASARKAN DATA MIKROTREMOR DI ACEH UTARA
Sri Cici Desmita
NIM 1804201010024

Program Studi Magister Teknik Sipil
Jurusan Teknik Sipil – Fakultas Teknik
Universitas Syiah Kuala
Abstrak

Analisis interaksi bangunan dan tanah dapat diidentifikasi dari nilai frekuensi natural tanah, frekuensi natural bangunan, damping ratio, resonansi dan indeks kerentanan bangunan, sehingga indeks kerentanan bangunan pada daerah gempa tertentu dapat dihitung. Penelitian ini mengidentifikasi respon bangunan terhadap gempa bumi, dengan cara menghitung nilai frekuensi natural tanah, dan nilai frekuensi natural bangunan, serta mengkaji hubungan antara frekuensi natural tanah dengan frekuensi natural bangunan. Penelitian ini juga mengidentifikasi faktor redaman untuk tipe bangunan yang berbeda, serta mengetahui pengaruh resonansi terhadap infrastruktur bangunan. Penelitian data mikrotremor menggunakan seismometer near-broadband. Alat perekam getaran tersebut diletakkan di tanah serta bangunan yang menjadi tinjauan yaitu bangunan sekolah dan kampus, pengukuran dilakukan disetiap lantai bangunan sebanyak 5 titik perlantai dan 1 titik di tanah selama 30 menit disetiap titik pengukuran. Metode yang digunakan yaitu metode Horizontal-to-Vertical Spectral Ratio (HVSR), Fast Fourier Transform (FFT), Floor Spectral Ratio (FSR), dan Random Decrement Metode (RDM) kemudian pengolahan data menggunakan Software Geopsy. Hasil perhitungan menunjukkan bahwa nilai frekuensi natural tanah berada pada range 0,7 - 0,85 Hz kecuali untuk lokasi gedung kampus yang nilainya mencapai 6,868 Hz, nilai ini dikarenakan tipe tanah pada daerah tersebut didominasi oleh batuan keras. Frekuensi natural bangunan (f0) berkisar 2,557 Hz - 4,292 Hz, frekuensi rendah dan memenuhi syarat SNI, untuk damping ratio bangunan berkisar 2,002 - 4,974%, kategori rendah memenuhi standar redaman yaitu 2 - 5%, kelima gedung tinjauan memiliki tingkat resonansi yang rendah karena nilai >25% sesuai dengan standar, batas periode getar alami bangunan aman sesuai SNI 17-02-2012 dan indeks kerentanan yang rendah.

Kata Kunci: Mikrotremor, Frekuensi Natural Tanah, Frekuensi Natural Bangunan, Resonansi, Indeks Kerentanan.

EARTHQUAKE RESPONSE AND VULNERABILITY STUDY OF PUBLIC BUILDINGS BASED ON MICROTREMOR DATA IN NORTH ACEH Sri Cici Desmita NIM 1804201010024 Master Program of Civil Engineering Civil Engineering Department of Engineering Faculty University of Syiah Kuala Abstract Analysis of the interaction of buildings and land can be identified from the value of the natural frequency of the soil, the natural frequency of the building, the damping ratio, the resonance, and the vulnerability index of the building so that the vulnerability index of the building in a certain earthquake area can be calculated. This study identifies the response of buildings to earthquakes, by calculating the natural frequency value of the soil, and the value of the natural frequency of the building, as well as assessing the relationship between the natural frequency of the soil and the natural frequency of the building. This study also identified damping factors for different building types, as well as knowing the influence of resonance on building infrastructure. Microtremor data research using a near-broadband seismometer. Alat vibration recorder is placed on the ground and the buildings that are being reviewed are school and campus buildings, measurements are carried out on each floor of the building at as many as 5-floor points and 1 point on the ground for 30 minutes at each measurement point. The methods used are the Horizontal-to-Vertical Spectral Ratio (HVSR), Fast Fourier Transform (FFT), Floor Spectral Ratio (FSR), and Random Decrement Method (RDM) methods then data processing using Geopsy Software. The calculation results show that the natural frequency value of the soil is in the range of 0.7 - 0.85 Hz except for the location of campus buildings whose value reaches 6.868 Hz, this value is because the soil type in the area is dominated by hard rocks. The natural frequency of the building (f0) ranges from 2,557 Hz - 4,292 Hz, low frequency and meets the requirements of SNI, for the damping ratio of the building ranges from 2,002 - 4.974%, the low category meets the damping standard of 2 - 5%, the five review buildings have a low resonance level because the value of >25% is following the standard, the limit of the natural vibrating period of safe buildings according to SNI 17-02-2012 and the low vulnerability index. Keywords: Microtremor, Soil Natural Frequency, Building Natural Frequency, Resonance, Vulnerability Index.