Perilaku lentur balok beton bertulang komposit beton normal-beton non pasir tampang T :: Blok tekan beton di dalam web
HANDAKA, Zuli Purwa, Ir. Hrc. Priyosulistyo, M.Sc.Ph.D
2006 | Tesis | S2 Teknik SipilMengingat kuat tekan beton non pasir lebih rendah dari beton normal maka pemakaian beton non pasir dibatasi pada struktur beton sederhana. Masih perlu dilakukan penelitian lebih lanjut,terutama tentang karakteristiknya sebagai balok komposit dalam memikul beban yang bekerja pada suatu struktur. Benda uji menggunakan balok T beton bertulang dengan dimensi: lebar efektif ( be ) = 500 mm,lebar badan ( bw ) = 150 mm, tebal flens ( tf ) = 60 mm, tinggi ( h ) = 300 mm dan panjang ( L ) = 2200 mm. Jumlah benda uji 3 buah, terdiri atas 1 buah balok T beton normal ,1 buah balok T komposit beton normal - beton non pasir dan 1 buah balok T beton non-pasir . Dalam penelitian ini benda uji dirancang sedemikian sehingga garis netral beton jatuh di bagian badan balok. Tulangan yang dipakai : diameter 19 mm untuk tulangan tarik, diameter 6 mm untuk tulangan tekan, dan diameter 10 mm untuk sengkang. Untuk beton normal dirancang memiliki kuat tekan (f’c ) = 20 MPa ,sedangkan beton non pasir dengan perbandingan semen dan agregat 1:2. Pengujian lentur balok T dengan 2 titik pembebanan. Dari hasil pengujian lentur diperoleh data beban, lendutan, regangan yang dianalisa sehingga diperoleh kapasitas momen, kekakuan, dan daktilitas balok. Melalui pengamatan pola retak yang terjadi dapat ditentukan jenis keruntuhan yang terjadi pada balok. Untuk mengetahui kuat lekat antara baja tulangan dengan beton non pasir digunakan benda uji kubus beton non pasir (150x150x150 mm ) dan baja tulangan deform diameter 19 mm. Selain itu juga dilakukan pengujian gaya geser friksi pada balok T komposit menggunakan benda uji 3 buah benda uji geser friksi antara beton normal dengan beton non pasir. Dari hasil pengujian lentur, diperoleh penurunan kapasitas momen balok T untuk BK-2 dan BNP-2 berturut-turut terhadap beton normal ( BN-2 ) sebesar 95.06 % dan 86.91%. Sedangkan analisa terhadap daktilitas balok, terjadi penurunan nilai daktilitas balok berturut-turut untuk BK-2 dan BNP-2 hingga sebesar 97.825 % dan 95.580 %. Hasil analisa terhadap nilai kekakuan lentur balok , terjadi penurunan kekakuan lentur balok hingga sebesar 83.04 % dan 92.99 % berturut-turut untuk BNP – 2 dan BK – 2. Dari pola retak yang terjadi, untuk BN-2 terjadi keruntuhan lentur, sedangkan pada BK – 2 dan BNP – 2 terjadi keruntuhan geser lentur. Hasil uji kuat geser friksi menunjukkan kuat geser antara beton normal dan beton non pasir sebesar 2.11 Mpa. Dari hasil uji pull out, menunjukkan bahwa kuat lekat beton non pasir dan tulangan deform 19 mm sebesar 4.435 Mpa .
The application of no fines concrete in the modestly structure is still limited due to the limitation of available compressive strength that lower than that normal concrete. To avoid the weakness, an advanced research should be done, especially in its characteristic as the composite beam to bear the load that working on the structure The T-beam specimens have the dimension of effective width (be) of 500 mm, web width(bw) of 150 mm, flange thickness (tf) of 60 mm, beam height (h) of 300 mm and beam span (L) of 2200 mm. The three specimens were provided in this research, where two of them have been made from normally concrete and no fines concrete in overall and the other one has been made as a composite of normally concrete and no fines concrete. The specimens were designed in such away that the neutral axis was lied at the web area. The utilized reinforcement: tensile bar of 19 mm in diameter, compressive bar of 6 mm in diameter, and stirrup bar of 10mm in diameter. Normal concrete is designed to have compressive strength of 20 MPa, while non-fine concrete is made of aggregate cement at the ratio of 1:2. Flexural test of the T-beam is done with two points of loading in order no shear stress to occur in the observed area. The test results in data of loads, strain, and deflection that are then analyzed to obtain capacity of moment, stiffness and ductility of the beam. The type of failure of the beam is perceived by observing the crack pattern. The bond strength of non-fine concrete is tested by pull-out test in which an steel bar of 19 mm in diameter is planted at each center of three non-fine concrete cubes (150x150x150mm). To view the shear friction in the contact area of the two different composite beams of different materials, a friction test is done. The result of ductility test shows decrease of T-beam moment capacity for BK-2 and BNP-2 against normal concrete (BN-2) as much as 95.06% and 86.91% respectively, whereas the analyzing of ductility of the beam shows decrease of Tbeam ductility for BK-2 and BNP-2 compare to BN-2 were 97.825 % and 95.580 % respectively. Analysis on the value of beam ductility stiffness shows decrease of beam ductility stiffness as much as 83.04% and 92.99% for BNP-2 and BK-2 respectively. The failure pattern showed that BN-2 was flexural failure while BK-2 and BNP-2 were flexural - shear failure. The result of shear friction test shows that the shear friction strength between normal concrete and no-fine concrete is 2.11 Mpa. The result of pull-out test shows the bond strength of non-fine concrete and 19 mm bar is 4.435 Mpa.
Kata Kunci : Balok Beton Bertulang,Beton Non Pasir,Komposit, Composite, momen capacity, ductility, stiftness
