Keandalan Menara Televisi Rangka Baja Akibat Beban Gempa

Indra Djati Sidi, Akhmad Ridhwan Ma’sum

Abstract


Abstrak

Perencanaan struktur menara telah bergeser dari konsep equal hazard menjadi konsep equal risk, dimana semua bangunan dirancang untuk mempunyai tingkat kegagalan atau risiko yang sama nilainya, dalam hal ini 1% dalam masa layan 50 tahun. Berkembangnya konsep ini disebabkan bahwa struktur menara televisi yang dirancang dengan konsep equal hazard ternyata mempunyai tingkat risiko yg tidak sama yang disebabkan oleh variabilitas dari tahanan menara terhadap gempa. Variabilitas kapasitas menara terhadap gaya gempa dipengaruhi oleh variasi gaya gempa yang bekerja yang dikenal sebagai record to record variation. Dalam makalah ini disampaikan model probabilitas untuk menghitung tingkat keandalan menara terhadap gaya gempa, dengan mengkombinasikan kurva hazard dan kurva fragilitas struktur menara. Kapasitas menara atau kurva fragilitas didapatkan dengan mencari peak ground acceleration (PGA) collapse dari menara dengan menggunakan incremental nonlinear time history analysis dari 40 pasang data time history. Reliability atau keandalan menara diperoleh dengan memanfaatkan total probability theorem yaitu dengan melakukan proses risk integral antara kurva hazard dan kurva fragilitas.

Abstract

The new earthquake design code emphasizes on uniform risk concept at every structure and every location which is 1% probability of collapse in 50 years, as stated in SNI 1726-2012. Indonesian television tower design, until this research is conducted, still uses the concept of uniform hazard ground motion, sample tower that is assessed in this research included. This research will assess probability of collapse of the sample tower as well as it’s performance. Probability of collapse is calculated by risk integrating fragility curve from two different loading direction and hazard curve at the site. The result will then be summarized with the probability of each loading direction included to get the total probability of collapse in 50 years. Fragility curve is generated by Incremental Dynamic Analysis process of 40 different earthquake records. The measured intensity is determined as PGA. The fragility curve is calculated with lognormal distribution parameters of median ( ) and standard deviation (β) which are obtained from the PGA data set of IDA result.


Keywords


Fungsi distribusi lognormal, kurva fragilitas, menara televisi, rangka baja, resiko keruntuhan, teori probabilitas total.

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References


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DOI: http://dx.doi.org/10.5614%2Fjts.2017.24.3.5

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