Perilaku lentur balok beton bertulang komposit beton normal-beton non pasir tampang T :: Blok tekan beton di dalam flens
CHANDRA, Yovi, Ir. Hrc. Priyosulistyo, M.Sc.Ph.D
2006 | Tesis | S2 Teknik SipilInovasi dan teknologi konstruksi beton sekarang ini sedang mengembangkan penggunaan beton non-pasir sebagai bahan bangunan dimana pembuatannya mudah, cepat dan dapat diaplikasikan pada struktur rumah sederhana. Untuk itu perlu penelitian perilaku dan karakteristik balok komposit antara beton normal dan beton non-pasir dalam memikul beban yang bekerja pada suatu struktur dengan blok tekan beton diusahakan di daerah sayap. Spesimen berupa 3 benda uji yang terdiri dari 1 buah balok T beton normal, 1 buah balok komposit T, dan 1 buah balok T beton non-pasir. Dimensi yang digunakan yaitu : lebar efektif (be) = 500 mm, lebar efektif badan (bw) = 150 mm, tebal sayap (hf) = 60 mm, tinggi (h) = 300 mm dan panjang balok (L) =2200 mm. Tulangan tarik berdiameter 12 mm, tulangan tekan dan sengkang berdiameter 6 mm. Beton normal dirancang f’c=20 MPa dan beton non pasir dirancang dengan perbandingan 1:2. Data pengujian yang diambil berupa nilai beban, regangan dan lendutan dianalisis sehingga diperoleh kapasitas momen, kekakuan, daktilitas. Melalui pola retak akibat beban statis diperoleh jenis keruntuhannya. Selain itu juga dilakukan penelitian kuat lekat antara baja tulangan menggunakan kubus (15x15x15)cm dengan tulangan D12, dan pengujian gaya geser friksi pada balok T komposit menggunakan 3 kubus (15x15x15)cm dimana 1 kubus beton normal diapit dengan 2 kubus beton non pasir dengan tinggi bidang gesek 7,5 cm. Hasil pengujian lentur pada balok T BK-1 dan BNP-1 dibandingkan terhadap beton BN-1 diperoleh penurunan kapasitas sebesar 1,35 % dan 8,53 %. Analisis daktilitas balok BK-1 dan BNP-1 bila dibandingkan terhadap balok BN-1 diperoleh penurunan daktilitas sebesar 4,98 % dan 12,68 %. Penurunan nilai kekakuan lentur balok BK–1 dan BNP–1 mencapai 1,46 % dan 6,49 % terhadap balok BN-1. Pola retak balok BN-1, BNP-1 dan BK-1 adalah keruntuhan lentur dimana terjadi retak dimulai dari tengah bentang sampai sepertiga panjang balok dan semakin melebar menuju sumbu netral penampang. Hasil pengujian kuat lekat beton non-pasir dengan tulangan diameter 12 mm diperoleh sebesar 8,1848 MPa. Hasil pengujian geser friksi menunjukkan kuat geser sebesar 2,111MPa .
Recently, innovation in concrete construction technology has been developed especially the use of no-fine concrete as building materials due to the ease in production, low in specific gravity and simple in process of construction so that it is appropriate to be used in modestly house structure. In order to more understand of characteristic of no fine concrete, it should be done a further research, especially in the study of characteristic behavior of composite materials between normal concrete and no fine concrete, where the neutral axis of the beam was lied at the flange of T beam. Three specimens were made. It consists of one normal concrete T beam, one composite T beam, and one beam of no fine concrete. The dimensions used in the model were 500 mm wide of effective flange, 150 mm wide of web, 60 mm thick of wing, 300 mm high of beam. The span of the model was 2200 mm and loaded with two point of loading. The diameter of longitudinal and stirrups were 12 mm and 6 mm respectively. The mixes of normal concrete was designed to achieve 20 MPa of compressive strength, whereas no fine concrete mixes was made with aggregate cement ratio of 1:2 by volume. The data taken in this research were load value, strain, deflection and then to be analyzed to obtained moment capacity, stiffness and ductility of the beam. The type of failure could be perceived by observation of the crack pattern. In order to study bond strength between no fine concrete and reinforcing steel, a pull out test has been run by using cube specimens (15x15x15)cm with 12 mm bar that planted of the center of the cube. In order to view the shear friction in the contact area of two different material of composite beam, the friction test has been done. The result of flexural test showed that the degradation of moment capacity of BK-1 and BNP-1 compare to BN-1 were 1,35 % and 8,53 % respectively. The ductility analyses of the beam for BK-1 and BNP-1 in comparison to BN-1 showed that the degradation of ductility were 4,98 % and 12,68 % respectively. Degradation of stiffness of the flexural beam of BK-1 and BNP-1 in comparison to BN-1 reached 1,46 % and 6,48 % respectively. By observation of the crack pattern, it could be concluded that the failure of the beam was flexural failure type. The result of pull out test showed that the bond strength between no-fine concrete and 12 mm bar was 8,185 MPa , whereas the result of shear friction test showed that the shear friction strength between normally concrete and no fines concrete was 2,111 MPa.
Kata Kunci : Balok Beton Bertulang,Non Pasir, Perilaku Lentur, Composite, moment capacity, ductility, stiffness.
