Kinerja Isolator Bola-Pegas pada Model Struktur Fleksibel Skala Kecil

Benyamin Bontong, Harun Mallisa, Tan Suryani Sollu

Abstract


Abstrak. Keruntuhan gedung akibat gempa masih menjadi masalah yang perlu dipecahkan. Penelitian ini mempelajari kinerja isolator seismik bola-pegas pada model struktur fleksibel satu lantai skala kecil. Massa model pada level atas dan bawah masing-masing 30 kg. Bola isolator dipasang di antara model struktur dan landasan getar. Pegas dengan konstanta 500N/m dipasang untuk memulihkan model ke posisi semula pasca getaran. Satu ujung pegas diikat pada setiap sudut bawah model dan ujung lainnya diikat pada landasan getar. Kolom dari model dengan konstanta pegas 22117 N/m, dijepit pada ujung atas dan bawah. Getaran sinusoidal diaplikasikan pada landasan getar dengan frekuensi 10.6, 15.35 dan 20.44 rad/s serta amplitudo 5, 10, 15 dan 20mm. Hasil penelitian menunjukkan bahwa respons percepatan model as, meningkat secara linier terhadap peningkatan percepatan landasan am, sedangkan rasio respons percepatan model terhadap percepatan landasan (as/am) berkurang seiring dengan peningkatan percepatan landasan. Isolator bola-pegas sangat efektif mereduksi percepatan terutama pada percepatan landasan yang relatif tinggi. Pada percepatan landasan rendah (0.05g),
rasio reduksi percepatan (am-as)/am, mencapai 39% pada level atas dan 45% pada level bawah, sedangkan pada percepatan landasan lebih dari 0.2g, rasio reduksi percepatan tersebut mencapai lebih dari 80% pada kedua level.

Abstract. The collapse of buildings due to the earthquake is still an issue that needs to be solved. This research studied the performance of the ball-spring seismic isolator on a reduced scale, single-story, flexible structure model. Model’s mass on each top and bottom level is 30 kgs. Ball isolator is mounted between the structure model and vibrating base. A spring constant support of 500N/m is installed to restore the model to its original position after the vibration. One end of the spring is tied to each bottom corner of the model and the other end is tied to the vibrating
base. The column of the model with the spring constant of 22,117 N/m, are clamped at the lower and upper ends. Sinusoidal vibrations were applied on vibrating base with the frequencies of 10.6, 15.35 and 20.44 rad/s and the amplitudes of 5, 10, 15 and 20 mm. The results show that the model acceleration response rates (as) increase linearly to increasing the base acceleration rates (am), while the ratio of the acceleration responses model to the base acceleration (as/am) decreases with an increasing the base accelerations. Ball-spring isolators very effectively reduces acceleration especially at the level of high rates of the base acceleration. At the level of the lower base acceleration (0.05g), acceleration reduction ratios, (am - as)/am, reach 39% at the top level and 45% at the bottom level, while the base acceleration of more than 0.2g the acceleration reduction ratios reach more than 80% at the both level.

Keywords


Struktur fleksibel; Isolator bola-pegas; Frekuensi; Amplitudo; Percepatan.

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References


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DOI: http://dx.doi.org/10.5614%2Fjts.2012.19.3.5

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