Pengaruh jenis sambungan terhadap keruntuhan lentur balok laminasi galar bambu petung

MULYATI, Dr.Ir. Fitri Mardjono, M.Sc

2005 | Tesis | S2 Teknik Sipil

Pemanfaatan bambu sebagai komponen bangunan dalam bentuk balok, yaitu dengan dikembangkan balok laminasi bambu. Untuk memperoleh balok laminasi bambu dengan bentang panjang diperlukan penyambungan. Kegagalan pada suatu struktur yang memakai sambungan sering disebabkan oleh gagalnya sambungan. Oleh karena itu, pada penyambungan balok laminasi bambu perlu diketahui pengaruh jenis sambungan terhadap perilaku mekanikanya. Penelitian ini bertujuan untuk mengetahui pengaruh jenis sambungan terhadap keruntuhan lentur balok laminasi galar bambu petung. Uji pendahuluan dilakukan untuk mengetahui sifat fisika dan mekanika bambu petung dengan menggunakan standar pengujian ISO-1975. Benda uji balok laminasi dibuat dari lembaran galar bambu petung dengan ukuran panjang bentang 270 cm, lebar 5 cm, dan tinggi 10 cm yang tersusun dari 14 lapis lamina yang masing-masing mempunyai ketebalan 0,75 cm. Antar lapisan lamina dan sambungan digunakan bahan perekat setting dingin. Pengempaan dilakukan menggunakan hydraulic jack dengan tekanan 2,0 MPa untuk balok laminasi dan 1,5-2,0 MPa untuk sambungan. Jumlah benda uji adalah 15 buah balok dengan lima variasi, masing- masing variasi dibuat 3 buah balok uji yaitu balok laminasi tanpa sambungan, balok laminasi dengan sambungan miring bertingkat (stepped scarf joint) arah vertikal dan horisontal, serta balok laminasi dengan sambungan jari (finger joint) arah vertikal dan horisontal. Sambungan pada balok laminasi diletakkan di tengah bentang. Pengujian balok laminasi dilakukan dengan pembebanan statik untuk kondisi four point bending pada jarak sepertiga bentang. Pembebanan dihentikan apabila balok telah mengalami kerusakan. Hasil pengujian sifat fisika dan mekanika bambu petung diperoleh nilai kadar air 11,25%, kerapatan 0,70 g/cm3, kuat tekan sejajar serat 51,64 MPa, kuat tekan tegak lurus serat 49,06 MPa, kuat tarik sejajar serat 391,30 MPa, kuat geser sejajar serat 14,19 MPa, kuat lentur 163,22 MPa, dan modulus elastisitas 9723,14 MPa. Hasil pengujian balok laminasi dengan sambungan menunjukkan terjadinya penurunan kuat lentur terhadap balok laminasi tanpa sambungan. Untuk balok laminasi dengan sambungan miring bertingkat arah vertikal dan horisontal sebesar 77% dan 78%, sedangkan untuk balok laminasi dengan sambungan jari arah vertikal dan horizontal sebesar 28% dan 47%. Selama pengujian, balok laminasi mengalami kerusakan lentur dan diikuti kerusakan geser. Kata kunci: bambu petung, balok laminasi, sambungan, dan keruntuhan

The application of bamboo as a structural component is as a beam by developing bamboo glued-laminated beam. To attain a long span of bamboo glued-laminated beam needs joining. Joint failure frequently causes failure in a structure that uses joint. Therefore, it was necessary to know the influences of joint towards the mechanical behavior of bamboo glued-laminated beam at its joint. This research aimed to know the influences of joint types to the bending failure of glued-laminated beam of petung bamboo pounded flat board. The preliminary test was conducted to know the physical and mechanical characteristic of petung bamboo by using the ISO-1975 standard test method. Specimen of glued-laminated beams were made of the sheet of the petung bamboo board of 270 cm long, 5 cm wide, and 10 cm high that consisted of 14 lamina layers each of which is 0.75 cm thick. A cold setting adhesive material was used between the lamina layers and joint. Pressing was conducted by using hydraulic jack with pressure at 2.0 MPa for glued-laminated beam and 1.5-2.0 MPa for joint. The total sample was 15 beams with 5 variations; 3 sample beams were used for each variation, i.e. glued- laminated beam without joint, glued-laminated beam with stepped scarf joint at vertical and horizontal direction, and glued-laminated beam with finger joint at vertical and horizontal direction. The joint at the gluedlaminated beam was placed in the center of the span. Te test of glued-laminated beam was conducted by using static loading for four point bending condition at a distance of one-third span. Loading was stopped as soon as the beam had been damaged. The test result of physical and mechanical characteristic of petung bamboo obtained the value of the moisture content of 11.25%, the density of 0.70 g/cm³, the value of the compression strength parallel to grain of 51.64 MPa, the value of the compression strength upright to grain of 49.06 MPa, value of the tensile strength parallel to grain of 391.30 MPa, value of the shear strength parallel to grain of 14.19 MPa, Modulus of Rupture of 163.22 MPa, and Modulus of Elastic of 9723.14 MPa. The test result of glued-laminated beam with joint indicated a decrease of bending strength to the glued-laminated beam without joint. For glued-laminated beam with stepped scarf joint at vertical and horizontal direction, the decrease is 77% and 78%, while for glued-laminated beam with finger joint at vertical and horizontal direction is 28% and 47%. During the test, the beams experienced bending failure and fo llowed by the shear damage

Kata Kunci : Balok Laminasi,Galar Bambu Petung,Keruntuhan Lentur,Jenis Bangunan, petung bamboo, glued-laminated beam, joint, and bending failure