Resmi Bestari, Resmi
Staf Pengajar Jurusan Teknik Sipil, Universitas Mercu Buana, Jakarta.

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Frekuensi Getar Alami Balok Kantilever Timoshenko Bestari, Resmi; Nasution, Amrinsyah
Jurnal Teknik Sipil Vol 11, No 4 (2004)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (337.711 KB)

Abstract

Abstrak. Teori gerak dinamis sistem dengan sifat beban terbagi rata pada balok umumnya menggunakan teori Euler-Bernoulli, hal mana anggapan bidang penampang tegak lurus sumbu balok akan tetap tegak lurus setelah terjadi deformasi akibat beban. Didalam memperhitungkan pengaruh deformasi akibat gaya geser, ketetapan ini tidak lagi berlaku, bahwa bidang penampang tidak tegak lurus lagi terhadap sumbu balok setelah terjadi deformasi [Wang, 1995]. Efek deformasi geser ini mempunyai pengaruh yang berarti terhadap frekuensi getar alami struktur, bila ukuran penampang relatif besar dibandingkan dengan panjang struktur/balok, disamping momen inersia akibat percepatan rotasi dari penampang balok juga tak dapat diabaikan. Analisis sistem seperti ini diselesaikan berdasarkan teori dari Timoshenko yang memperhitungkan pengaruh deformasi geser dan inersia rotasi pada balok.Makalah ini membahas penyelesaian eksak frekuensi getar alami balok dengan memperhitungkan pengaruh deformasi geser dan inersia rotasi pada balok. Jumlah ragam getar yang terjadi menjadi tertentu, jika kedua pengaruh tersebut diperhitungkan.Abstract.  Exact solution for dynamic system with distributed mass in elastic state is commonly analyzed by Euler-Bernoulli theory, that is ‘plane cross sections perpendicular to the axis of the beam remains plane and perpendicular to the axis after deformation [Wang, 1995]. Due to effect of transverse shear deformation, the plane cross sections remain plane but not necessarily normal to the longitudinal axis after deformation. This effect may have significant influence on the natural frequency of the large and deep beam. Also, the inertial resistance to rotational acceleration of the beam could not be ignored for the large and deep beam. Investigation is made for these two conditions by the use of Timoshenko’s beam theory. This paper presents exact solution of natural frequency, of which shear deformation and rotary inertia effects are included in the analysis. Numbers of mode-shapes become definite if which shear deformation and rotary inertia effects are included in the analysis
Real Response Modification Value of Reinforced Concrete Structures Using the Pushover Method in Horizontal Irranged Buildings Octaviani, Rien; Bestari, Resmi; Sukamdo, Pariatmono
ASTONJADRO Vol. 14 No. 1 (2025): ASTONJADRO
Publisher : Universitas Ibn Khaldun Bogor

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32832/astonjadro.v14i1.16264

Abstract

The country of Indonesia is prone to earthquakes, because geographically Indonesia is located at the meeting point of four tectonic plates, namely the Asian continental plate, the Australian continental plate, the Indian Ocean plate and the pacificocean plate. An earthquake is a vibration or shock that occurs on the surface of the earth due to the sudden release of energy from within, creating seismic waves. Earthquakes are usually caused by movements of the earth's crust (earth plates). Planning an earthquake-resistant building structure in Indonesia is very important, because most areas in Indonesia are in fairly high earthquake areas, so earthquake regulations, namely SNI 1726-2019, have been issued. Design re-planning or follow-up can be done using the real R value. If in the SRPMK structure the real R value is greater than the design R, then the planner can save reinforcement by re-analyzing the structure using real R. With the results of this research analysis, it can be concluded that the SRPMK structure with horizontal irregularities at the Jakarta location, produces a real modified response (R) value (referring to the ATC-40 limit on the ratio of deviations between floors and the rotational capacity of structural components) which is smaller than the specified maximum value. on SNI. In accordance with the provisions of ATC-40, all structural configurations are included in the Damage Control (DO) category level, which means that the transition between Immediate Occupancy (IO) SP-1 and Life Safety (LF) SP-3, the building is still able to withstand the forces of the earthquake that occurred, with the risk of human loss is very small. Only SRPMB's 8-story medium ground structure is included in the Life Safety (LF) category level SP-3. The real R value obtained in the SRPMK structure varies between 7.218 – 8.515. The results of this analysis are not significantly different from existing provisions, and in soft soil conditions the value is smaller than for the SRPMB structure. Real R less than the provisions is the maximum value that can be used based on this research. The real R value obtained in the SRPMB structure varies between 5.081 – 10.276. The results of this analysis are very different from the existing provisions for both soft and medium soil conditions; and Structural optimization has been carried out in each building configuration, but it was found that the cross-sectional dimensions of the SRPMB columns and beams in soft soil conditions were the largest cross-sectional dimensions compared to the others.