Tinjauan Nilai Faktor Modifikasi Respon (R) dan Faktor Kuat Lebih (O) pada Struktur Gabungan Rangka Baja dan Rangka Beton Bertulang dengan Analisis Pushover
Keywords:
Faktor modifikasi respon, Faktor kuat lebih, Analisis pushover, Struktur gabungan.Abstract
Abstrak. Adanya peningkatan kebutuhan ruang yang semakin tinggi serta didukung oleh regulasi yang berlaku khususnya di daerah padat, memungkinkan perluasan vertikal bangunan. Perluasan vertikal seringkali dilakukan dengan menambah struktur rangka baja yang berdiri di atas struktur eksisting dari rangka beton bertulang. Sistem pemikul beban lateral pada struktur yang diperluas dapat menggunakan kinerja gabungan rangka momen baja dan rangka momen beton bertulang sebagai kesatuan sistem rangka momen. Adanya perbedaan material struktur mempengaruhi pemilihan nilai R (faktor modifikasi respon) untuk perhitungan beban gempa. Nilai R untuk kategori sistem rangka pemikul momen gabungan baja dan beton belum secara eksplisit diatur oleh SNI 1726:2012. Maka dari itu, tulisan ini bertujuan untuk meninjau nilai R serta Ωo (faktor kuat lebih) pada struktur gabungan rangka momen baja sebagai struktur atas dan struktur rangka beton bertulang sebagai struktur bawah. Tinjauan yang dilakukan terbatas pada struktur yang berada pada kondisi kegempaan seperti di Kota Jakarta dengan kondisi Tanah Lunak (SE). Nilai R pada struktur gabungan ditetapkan terlebih dahulu untuk melakukan perancangan elemen struktur. Kemudian dilakukan analisis pushover sehingga diperoleh kurva gaya terhadap deformasi struktur untuk memverifikasi nilai R dan Ωo yang mampu dicapai. Konsep yang dipakai dalam menghitung nilai R dan Wo mengacu ATC-19 dan ATC-34 serta FEMA P-695.Abstract. A significant increasing of the space demand and supported by the applicable regulation especially in the congested areas, give the possibility to extend the building vertically. The extention can be done by adding the steel frame structures above the existing reinforced concrete structures. Thus, the lateral force resting system of the steel and reinforced concrete hybrid structures relies on the acting performance of the steel and concrete moment frames concurrently. This structural material distinction implies the selection of R (Response Modification Factor) value. The R value for hybrid steel-concrete moment resisting frame system has not been stipulated on SNI 1726:2012. Therefore, this paper aims to review the R and Ωo (overstrength factor) value of the hybrid steel-concrete moment resisting frame systems where the steel frames stands above the concrete frames. The review is limited to the structures having similar seismic condition as Jakarta with soft soil condition (Site Class SE). The R value on the hybrid structures is determined prior to structural elements design. Pushover analysis is then performed in order to obtain the load versus deformation curve for the recalculation of R and Ωo. The calculation concept of R and Ωo follows ATC-19 and ATC-34 including FEMA P695.
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