PENGARUH BEBAN DINAMIK GEMPA VERTIKAL PADA KEKUATAN KUDA-KUDA BAJA RINGAN BENTANG 6 METER STARTRUSS TIPE-C

MURSALIM NINOY LA OLA, Dr. Ir. Bambang Supriyadi, CES., DEA; Prof. Ir. Henricus Priyosulistyo, M.Sc., Ph.D,

2015 | Tesis | S2 Teknik Sipil

pada rangka atap rumah tinggal. Sebagai struktur rangka atap pengganti, kudakuda baja ringan perlu diuji kelayakannya. Salah satu karakteristik yang perlu diuji adalah kemampuan dalam menahan beban gempa vertikal, karena kuda-kuda sangat dominan menerima beban arah vertikal. Penelitian ini bertujuan mengetahui karakteristik kuda-kuda baja ringan merk startruss dengan bentang 6 m terhadap beban gempa vertikal. Metode pengujian dilakukan dengan mengamati lendutan, regangan, dan frekuensi alami kuda-kuda baja ringan terhadap pengujian statik dan pengujian dinamik. Beban yang diberikan berupa beban titik yang merupakan ekivalen beban mati atap multiroof dan atap genteng untuk jarak antar kuda-kuda 1,2 m. Hasil pengujian statik pada beban 80 kg per join atas kuda-kuda menunjukkan regangan statik 116 dan lendutan 3,87 mm, aman terhadap kontrol lendutan L/240. Dari pengujian dinamik didapatkan periode alami kuda-kuda lebih rendah dibanding periode gempa Yogyakarta 2006 dengan rasio redaman sekitar 2%. Dari hasil simulasi didapatkan bahwa kuda-kuda aman terhadap gempa vertikal karena memiliki frekuensi alami yang lebih besar dari frekuensi resonanso.

Nowdays cold formed truss is an alternative material instead of wood truss as a roof structure of building. As a replacement truss structure, cold-formed truss need to be tested for it’s ability. One of the characteristics that need to be tested is the capacity to withstand vertical seismic loads, because a truss is substantially loaded in vertical direction. This study aims to investigate the characteristics of cold formed truss of startruss brands with 6 m span against vertical seismic loads. Methods of testing is carried out by observing deflection, strain, and natural frequency of cold formed truss due in the static and dynamic testing. The truss is loaded by equivalent point load to represent multiroof tiles and tiles with 1.2 m spacing between truss. The results of static load tests of 80 kg per joints at upper side of the truss shows a static strain of 116 με and 3.87 mm deflection, which is safe within the L/ 240 deflection control. The truss natural period is obtained by dynamic testing which is lower than the earthquake period of Yogyakarta Quake in 2006 with a damping ratio of approximately 2%. From the simulation results showed that the truss is safe from vertical earthquake since the natural frequency is higher than the resonant frequency.

Kata Kunci : rangka atap, baja ringan, beban gempa vertikal