Analisis Efektivitas Bantalan Elastomer Bearing dalam Mereduksi dampak Pounding pada Bangunan Bertingkat Beton Bertulang dengan Beban Gempa Riwayat Waktu

M. Riski Audri Rahman, Ir. Ashar Saputra, ST., MT., Ph.D., IPM. ASEAN.Eng ; Prof. Ir. Iman Satyarno, M.E., Ph.D

2024 | Tesis | S2 Teknik Sipil

Berbagai investigasi seismik telah mengidentifikasi benturan antara bangunan yang berdekatan sebagai salah satu bahaya utama, terutama karena jarak yang terbatas di antara bangunan. Oleh karena itu, penilaian risiko benturan seismik menjadi krusial dan harus dipertimbangkan dalam revisi peraturan desain bangunan di masa mendatang. Getaran lateral pada bangunan yang berdekatan dapat memicu respons torsi akibat benturan saat gempa. Penelitian ini bertujuan mengurangi dampak benturan antarbangunan beton bertulang melalui penggunaan elastomer bearing.

Studi ini mengevaluasi perilaku benturan pada bangunan-bangunan di Kota Surabaya yang dirancang berdasarkan peraturan lama tanpa memperhitungkan efek benturan. Penelitian ini mengkaji desain ketahanan gempa untuk struktur yang diperkuat, sesuai SNI 1726:2019, serta mengevaluasi bagaimana benturan antarbangunan mempengaruhi perilaku struktur dan efektivitas elastomer bearing dalam mereduksi dampak benturan. Analisis nonlinear time history dilakukan pada tiga bangunan berdekatan, menggunakan tiga pasang rekaman gempa yang diskalakan sesuai SNI 8899:2020, mewakili gempa Megathrust, Benioff, dan Shallow Crustal. Tiga model dianalisis: Model 1 tanpa elemen link, yang memungkinkan setiap bangunan bergerak bebas; Model 2 dengan link dan asumsi benturan beton dengan celah 50 mm; serta Model 3 dengan link elastomer bearing dan asumsi benturan dengan celah 9 mm.

Hasil penelitian menunjukkan penurunan nilai mode shape pada Model 2 dan 3 dibandingkan dengan Model 1. Penggunaan elastomer bearing terbukti efektif dalam mencegah benturan antarbangunan dan mengurangi gaya tumbukan (link force) dari 51.776 kN menjadi 4.899 kN. Dengan kapasitas bearing sebesar 6.276 kN, elastomer bearing mampu menahan gaya aksial yang bekerja. Secara keseluruhan, penggunaan elastomer bearing efektif mengurangi gaya tumbukan sebesar 58% hingga 91% pada berbagai jenis gempa. Elastomer bearing tidak hanya mencegah benturan antarbangunan tetapi juga mampu menahan gaya aksial, sehingga meningkatkan keselamatan dan integritas struktur beton bertulang yang berdekatan.

Various seismic investigations have identified collisions between adjacent buildings as a significant hazard, primarily due to the limited separation distance between structures. Therefore, assessing the risk of seismic pounding is critical and should be considered in future revisions of building design codes. Lateral vibrations in adjacent buildings can induce torsional responses during seismic events due to the impact. This study aims to mitigate the effects of collisions between reinforced concrete buildings by utilizing elastomer bearings.

This research evaluates pounding behavior in buildings located in Surabaya City, which were designed based on older codes that did not account for pounding effects. The study examines seismic-resistant designs for retrofitted structures in accordance with SNI 1726:2019 and evaluates how building collisions influence structural behavior and the effectiveness of elastomer bearings in mitigating the impact. Nonlinear time history analyses were conducted on three adjacent buildings using three pairs of scaled earthquake records in compliance with SNI 8899:2020, representing Megathrust, Benioff, and Shallow Crustal earthquakes. Three models were analyzed: Model 1 without link elements, allowing each building to move independently; Model 2 with link elements assuming concrete collisions with a 50 mm gap; and Model 3 with elastomer bearing links assuming collisions with a 9 mm gap.

The results show a reduction in mode shape values in Models 2 and 3 compared to Model 1. The use of elastomer bearings effectively prevented building collisions and reduced the impact force (link force) from 51,776 kN to 4,899 kN. With a bearing capacity of 6,276 kN, the elastomer bearings could withstand the axial forces acting on them. Overall, elastomer bearings proved effective in reducing impact forces by 58% to 91?ross various earthquake types. In addition to preventing building collisions, elastomer bearings also demonstrated the ability to sustain axial forces, thereby enhancing the safety and structural integrity of adjacent reinforced concrete buildings.

Kata Kunci : pounding effect, nonlinear time history, RC frame structure, elastomer bearing