Uji beban lateral kelompok tiang beton dengan Pilecap tipis pada tanah lempung lunak

FIRDAUS, Muhammad, Dr.Ir. Hary Christady Hardiyatmo, M.Eng.,DEA

2006 | Tesis | S2 Teknik Sipil

Di lapangan sering dijumpai tanah lempung lunak dengan volume yang cukup besar. Penggunaan fondasi kelompok tiang mengapung dengan pelat penutup (pile cap) yang berfungsi untuk menyatukan ujung tiang dan mendistribusikan beban ke masing-masing tiang diharapkan dapat memberikan perlawanan terhadap pengaruh gaya lateral yang bekerja pada konstruksi khususnya penerapan untuk bangunan konstruksi tower akibat beban angin dan dermaga akibat beban benturan kapal. Pelat (pile cap) tipis ukuran 3 x 1 meter yang didukung perkuatan kelompok tiang dengan panjang (L) = 1 meter dan diameter (φ) = 0,1 meter yang dipancang pada tanah lempung sebanyak 12 buah. Media lempung ukuran 3,5 x 1,5 meter, kedalaman 1,5 meter. Pelaksanaan pengujian pembebanan lateral pada fondasi berdasarkan ASTM D420-D3966. Pendekatan analisis dan perancangan menggunakan metode Beam on Elastic Foundation (BoEF) dan metode Broms. Pemberian beban lateral maksimum 30 kN menyebabkan lendutan pile cap bertambah besar untuk letak momen dekat dengan pusat pelat (pile cap) dan memperkecil pengaruh displacement lateral pada perletakan 0,25 meter dari tepi pile cap. Perhitungan BoEF untuk kv-momen dengan hasil pengamatan diperoleh selisih antara 57% sampai 9 %, hitungan BoEF dengan memakai kv-PLT terkoreksi selisih di atas 400 %. Analisis perilaku defleksi tiang dengan metode Broms terhadap hasil pengamatan memperlihatkan selisih perhitungan antara 27 % sampai 6 %.

Most clay in the field was found in great volume. The usage of floating piles with pile cap were to group the piles and to distribute the loads into each pile. This condition could give resistances due to eccentric lateral load on the construction.The application of this research were in tower construction under wind load and port construction under impact load due to the ships. The dimension of pile cap was 3m x 1m and was supported by group of piles. The length (L) and diameter (φ) of each pile were subsequently 1m and 0,1m. All 12 piles were driven to clay in a sample box. The dimension of sample box was 3,5m x 3,5m x 1,5m. Loading tests were carried out based on ASTM D420-D3966 code. Approachments used for analysis and design were Beam on Elastic Foundation Method (BoEF) and Brom Method. The application of maximum lateral loads at 30 kN that had increased the defelection of pile cap especially near the center of the pile cap and small influence of lateral displacement at 0.25 m from the edge of pile cap. The differences between BoEF analysis with kv-momen and monitoring results were variated within range 57 % to 9 % and the between BoEF analysis with corrected kv-PLT and monitoring results were above 400 %. The differences of pile deflection between Broms method and monitoring results on lateral displacement were within range 27 % to 6 %.

Kata Kunci : Pile cap, perkuatan kelompok tiang, beban lateral eksentris, lendutan, displacement lateral, BoEF, piles group reinforcement, eccentric lateral load, deflection, lateral displacement