Studi Perancangan Bangunan Tahan Gempa dan Tsunami di Kepulauan Mentawai, Sumatera Barat

Tsunami adalah bencana alam berupa gelombang air dengan periode panjang, yang salah satu penyebabnya ialah gempa bumi tektonik. Sebagai negara yang berada di antara pertemuan tiga lempeng tektonik; Indo – Australia, Eurasia, dan Pasifik, hal tersebut menyebabkan kawasan Indonesia rentan terjadi gempa bumi tektonik hingga tsunami. Tsunami destruktif dapat memberikan berbagai dampak terhadap apapun yang dilaluinya; baik infrastruktur maupun jiwa penduduk. Sehingga, dibutuhkan suatu bangunan yang mampu menahan gempa bumi hingga tsunami bagi penduduk Indonesia untuk meminimalisir dampak yang tersebut. Bangunan vertikal yang didesain harus memenuhi standar dan kriteria bangunan tahan tsunami. Dalam SNI 1727 – 2020 dan FEMA P – 646, dijelaskan bahwa level kinerja minimal suatu bangunan yang layak digunakan sebagai bangunan tahan tsunami ialah pada level Immediate Occupancy. Maka, dalam perencanaan penulisan ini akan digunakan metode Performance Based Design (PBD) yang ditunjang dengan analisa non – linier berupa Pushover Analysis, guna mengetahui level kinerja suatu bangunan. Desain bangunan vertikal tahan gempa dan tsunami pada penulisan ini direncanakan di Kepulauan Mentawai, Sumatera Barat. Konstruksi yang digunakan ialah baja bersistem bracing eksentris atau Eccentrically Braced Frames (EBF), dengan sistem sambungan berupa Reduced Beam Section (RBS). Dari hasil analisis dan perhitungan, didapatkan tebal pelat lantai yang digunakan adalah 10 cm serta 9 cm. Untuk profil yang digunakan, yaitu dimensi bracing WF 400 x 400 x 25 x 30, dimensi balok induk WF 800 x 300 x 14 x 26 dan WF 800 x 300 x 14 x 22, dimensi balok link WF 700 x 300 x 15 x 28, dimensi balok anak WF 350 x 250 x 9 x 14, dimensi kolom WF 500 x 500 x 70 80, WF 400 x 400 x 30 x 50 dan WF 400 x 400 x 25 x 30. Spun pile berdiameter 80 cm digunakan sebagai pondasi yang dipancang pada kedalaman 18 m serta 20 m. ==================================================================================================== Tsunami is a disaster in form of a long wave period of water, which is triggered by an earthquake. As a country that is located in between three tectonic plates; Indo – Australia, Eurasia, dan Pacific, it makes Indonesia as one of countries with a high frequency of earthquake dan tsunami activities. Destructive tsunami could bring various impact to everything it passes through; infrastructure dan fatalities (death due to tsunamis). Hence, a vertical building that can resist earthquake and tsunami is needed to provide Indonesia’s citizens regarding to the occurance of a tsunami to minimalize the impacts itself. Particularly, in an area with a high risk level of both earthquake dan tsunami disaster. The vertical building to be designed needs to fulfil the standards dan building criterias of a tsunami resistant building construction. In SNI 1727 – 2020 and FEMA P – 646, it is said if a tsunami resistant building’s performance level needs to be at least in a level of Immediate Occupancy. Therefore, the method that is going to be used is Performance Based Design, supported by Pushover Analysis. Because, pushover analysis is able to inform the performance level of a building. The building that is going to be designed is located in Kepulauan Mentawai, West Sumatera. Eccentrically Braced Frames (EBF) is used as a system of the building, following the Reduced Beam Section (RBS) as a system for its connection. From the analysis that have been conducted, it is found that the floors’ thickness are 10 cm and 9 cm. The profiles that are used are, 400 x 400 x 25 x 30 for bracing, WF 800 x 300 x 14 x 26 and WF 800 x 300 x 14 x 22 for primary beam, WF 700 x 300 x 15 x 28 for link beam, WF 350 x 250 x 9 x 14 for secondary beam, WF 500 x 500 x 70 80, WF 400 x 400 x 30 x 50 dan WF 400 x 400 x 25 x 30 for column. Spun pile with a diameter of 80 cm is used as the foundation at the depth of 18 m and 20 m