Studi Perbandingan Analisis Statik dan Dinamik pada Girder Kereta Cepat
DOI:
https://doi.org/10.5614/jts.2024.31.1.2Keywords:
analisis dinamis, analisis statis, faktor amplifikasi dinamik, kereta cepat, respons strukturAbstract
Abstrak
Faktor perbesaran dinamis (dynamic amplification factor ? DMF) lazim digunakan oleh perencana untuk memperbesar respons struktur (gaya dalam, perpindahan) yang didapatkan dari analisi statis untuk mengakomodasi efek dinamis dari laju kendaraan. Di dalam beberapa Code, faktor amplifikasi dinamis cenderung berupa rumus empiris yang tergantung pada bentangan struktur, bukan pada laju kendaraan. Studi ini hendak mengevaluasi berapa faktor amplifikasi dinamis yang mungkin terjadi pada momen lentur dan lendutan girder kereta apabila laju kendaraan divariasikan dari 100 km/jam s.d. 550 km/jam. Pemodelan dan analisis didasarkan pada girder tipikal untuk kereta cepat untuk bentang 32,6 m dengan menggunakan software metode elemen hingga. Hasil analisis software pertama-tama diverifikasi dengan solusi eksak dari persamaan gerak dinamik untuk beban terpusat berjalan (moving load), kemudian dilanjutkan dengan analisis terhadap beban kereta cepat CR400AF. Perbandingan antara respons dinamis dan statis (faktor amplifikasi dinamis) yang direkomendasikan oleh Code cenderung konservatif untuk laju kendaraan rencana 350 km/jam.
Kata-kata Kunci: Respon dinamik, beban bergerak, kereta cepat, jembatan box girder, time history analysis.
Abstract
Dynamic amplification factor is commonly used by design engineers to amplify structural response (bending moment, deflection) obtained from static analysis to accommodate dynamic effect resulted from vehicle?s speed. In some design codes, this dynamic amplification factor is an empirical equation which is simply a parameter of girder length, not of speed. This study evaluates the possible amplification factor which migh occur when the speed is varied from 100 km/hour to 550 km/hour. The modeling and analysis is based on a typical girder for high speed train with girder length 32,6 m using finite element software. The results of software was firstly verified against exact solution of an equation of motion due to single concentrated moving load. Then, an analysis due to a high speed train CR400AF was carried out. The comparison between dynamic and static response (indicated by the dynamic amplification factor), be it maximum bending moment or mid span deflection, recommended by the design code tends to be conservative for operational speed of 350km/hour.
Keywords: Analisis dinamis, analisis statis, faktor amplifikasi dinamik, kereta cepat, respons struktur.
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