Desain Modifikasi Sistem Struktur Gedung Apartemen di Surabaya Menggunakan Sistem Outrigger Dan Belt-Truss

Apartemen Darmo Hill merupakan salah satu gedung tinggi di Surabaya dengan luas ± 38,569.69 m2, tinggi 128 meter, dan memiliki 34 lantai tower, 3 podium, 2 basement. Gedung Apartemen Darmo Hill Surabaya direncanakan menggunakan sistem ganda yang mengacu peta gempa Indonesia tahun 2010 dengan peraturan SNI 1726-2012. Seiring berjalannya pembaharuan peta gempa terbaru, perlu adanya evaluasi dengan peta gempa Indonesia tahun 2017. Berdasarkan hasil evaluasi, bahwa gedung tersebut mempunyai drift melebihi dari simpangan ijin. Untuk mengatasi masalah tersebut perlu dilakukan modifikasi sistem struktur menggunakan sistem outrigger dan belt-truss. Lokasi optimal outrigger dan belt-truss berada di tengah ketinggian bangunan, sehingga simpangan antar lantai struktur memenuhi syarat ijin. Perhitungan struktur mengacu pada peraturan yang terbaru yaitu SNI 2847-2013, SNI 1729-2015, ACI 318M-14, dan AISC 360-16. Sedangkan perhitungan pembebanan mengacu pada ASCE 7-16 dan SNI 1727-2013. Proses perhitungan struktur meliputi analisis pembebanan, permodelan struktur dengan ETABS 17, analisis gaya dalam, perhitungan penulangan. Dikarenakan sistem struktur dengan outrigger & belt-truss belum diatur secara signifikan dalam SNI 1726-2012, maka perencanaan struktur gedung tahan gempa dalam tugas akhir ini menggunakan desain berbasis kinerja dengan menggunakan nilai parameter gempa rencana yaitu; R=5, Ω_0=2.5 dan Cd=5. Nilai R, Ω_0, Cd didapat dengan analisa statik nonlinear untuk memperoleh nilai parameter gempa secara aktual. Berdasarkan hasil analisa perhitungan, sistem outrigger dan belt-truss dipasang di lantai 16. Dimana simpangan antar lantai akibat perubahan nilai percepatan peta gempa sudah memenuhi ketika memakai sistem outrigger dan belt-truss. balok outrigger yang digunakan memiliki ketebalan 300 mm dan breising belt-trus dengan profil PSB 300×16. Menurut ASCE 41-13 penentuan nilai parameter gempa secara aktual dengan desain berbasis kinerja melalu analisa statik nonlinear didapatkan nilai yaitu; R=5.76, Ω_0=1.68 dan Cd=2.99. Dengan demikian nilai R sudah memenuhi rencana awal, nilai Ω_0 aktual lebih kecil sehingga tidak perlu adanya desain ulang struktur bawah, nilai Cd lebih kecil berarti bahwa deformasi yang terjadi pada struktur tersebut masih memenuhi syarat ijin. Sedangkan menurut FEMA 440 melalui target perpindahan dan ATC-40 melalui batasan nilai drift, struktur tersebut masuk dalam tingkat kinerja struktur kategori Immediate Occupancy (IO). Dalam hal ini terdapat beberapa kerusakan struktur ringan sampai sedang namun perlu adanya perkuatan elemen kolom yang mengalami kerusakan berat agar struktur masih layak fungsi. ================================================================================================ Darmo Hill Apartment is one of the tallest buildings in Surabaya with ± 38,569.69 m2 wide, 128 meters tall, and consists of 34 tower stories, 3 podiums, and 2 basements. The Surabaya Darmo Hill Apartment was designed with the double system based on Indonesia earthquake map in 2010 according to SNI 1726-2012 regulation. Along the development of Indonesia earthquake map which is recently updated, the evaluation is needed based on Indonesia earthquake map in 2017. According to the evaluation, the building drift is higher than permit deviation. Therefore, structure system modification is necessary using the outrigger and belt-truss system. The optimal location of the outrigger and the belt-truss is in the middle of the building height, that the deviation among the structure stories fulfills the permit condition. The structure calculation based on the latest regulation those are SNI 2847-2013, SNI 1729-2015, ACI 318M-14, and AISC 360-16. While the load calculation is based on ASCE 7-16 and SNI 1727-2013. The structure calculation processes are the loading analysis, the structure modeling with ETABS 17, the internal force analysis, and the reinforcement calculation. As the structure system with outrigger and belt-truss has not been well regulated in SNI 1726-2012, therefore the earthquake resistant structure design in this final project using performance-based design using the parameter values of planned earthquake namely R=5, Ω_0=2.5 and Cd=5. The values of R, Ω_0, Cd is obtained with the nonlinear static analysis to gain an actual earthquake parameter value. Based on the calculation analysis, the outrigger and belt-truss system is installed on the 16th floor. Where the story drift as the change of the earthquake map acceleration value has met when the outrigger and belt-truss system is used. The outrigger beam used is 300 mm thick and the profile of the belt-truss used is PSB 300 x 16. According to ASCE 41-13 the determination of earthquake parameter value actually by the performance-based design through the nonlinear static analysis the values of R=5.76, Ω_0=1.68 and Cd=2.99 are obtained. Therefore, the R value has met the initial design, the value of actual Ω_0 is smaller than the initial thus the redesign of substructure is not needed, the Cd value is smaller than initial means that the deformation happened to the structure still met the permit condition. While according to FEMA 440 through the displacement target and ATC-40 through drift value limit, the structure is included in the performance structure level of Immediate Occupancy (IO) category. In this case, there are few structure light to moderate damages however heavy damage column element strengthen is needed therefore the structure is still worth the function