Hollow due to plumbing system has an effect to the building's visual and the aesthetic quality in terms of architecture. To overcome this, the pipe is planted in a construction structure such as a column. However, this will affect on the strength degradation and modes of failure of structural elements such as a column. The objective of this research is to study the strength, stiffness, ductility, cracking patterns, and modes of failure of hollow RC columns with square cross-section with various load eccentricity and concrete strength. In this research, 13 reinforced concrete columns with square cross section were made. Two of them were massive columns (C1E1, C1E2) with cross-sectional dimension of 150 x 150 mm2 and 800 mm long, six of them were hollow with the same size (C2E1, C3E1, C4E1, C2E2, C3E2, C4E2). Concrete strength fc'=34.52 MPa with eccentricity=60mm and fc'=35.72 MPa with eccentricity 100 mm. Models were analyzed by nonlinear finite element method using ATENA v.2.1.10 software. The FE model is calibrated against recent experimental results from Zacoeb (2003). Once validated, the model is used to examine stiffness, ductility, cracking patterns, and modes of failure of hollow RC columns with a square cross-section with various load eccentricity. The numerical results show that the different ultimate load strength of C1E1, C2E1, C3E1, C4E1, C1E2, C2E2, C3E2, C4E2 are 0,32%, 2,22%, 1,61%, 7,74%, 1,25%, 0,65%, 2,63%, 1,94%, while the differents stiffnes are 18,30%, 21,30%, 23,79%, 31,57%, 15,22%, 22,67%, 21,39%, 14,41%, and the differents ductility are 48,71%, 33,64%, 3,39%, 41,04%, 52,30%, 22,99%, 18,11%, 7,76%. Crack pattern occurred in C1E1, C2E1, C3E1, C4E1, C1E2, C2E2, C3E2, C4E2 are flexural crack and shear cracks. Exhibit modes of failure of C1E1, C2E1, C3E1, C4E1 are compression failure and C1E2, C2E2, C3E2, C4E2 are tension failure.Keywords: ATENA, columns, eccentricity, failure, hollow, nonlinearANALISIS NON-LINEAR KOLOM BETON BERTULANG PENAMPANG SEGIEMPAT BERONGGA DENGAN VARIASI EKSENTRISITAS BEBAN DAN MUTU BETONLubang akibat pemasangan pipa pada konstruksi untuk keperluan instalasi (air hujan, sanitasi, listrik dan lain-lain) dapat berpengaruh pada visualitas bangunan dan akan mempengaruhi kualitas estetika dari segi arsitektur. Untuk mengatasi hal tersebut pipa ditanam didalam struktur konstruksi seperti kolom. Akan tetapi hal ini akan menyebabkan degradasi kekuatan beton dan pola keruntuhan struktur pada kolom. Selain secara eksperimental, penelitian ini dapat juga dilakukan secara numeris menggunakan metode elemen hingga nonlinier. Penelitian ini bertujuan untuk mengetahui kekuatan, kekakuan, daktilitas, pola retak dan model keruntuhan kolom beton bertulang penampang persegi berongga dengan variasi eksentrisitas beban dan variasi mutu beton. Dalam penelitian ini dimodelkan 8 jenis kolom beton bertulang penampang segiempat yang terdiri dari 2 kolom masif (C1E1 dan C1E2) dan 6 kolom berongga (C2E1, C3E1, C4E1, C2E2, C3E2, C4E2) dengan ukuran 150 x 150 mm2, panjang 800 mm. Mutu beton fc'=34.52 MPa dengan eksentrisitas =60mm dan mtu beton fc'=35.72 MPa dengan eksentrisitas =100mm. Kolom dianalisis menggunakan software elemen hingga nonlinier ATENA V.2.1.10 dan hasilnya dibandingkan dengan hasil eksperimen sebelumnya dari Zacoeb (2003). Setelah model divalidasi, dilakukan perhitungan kekakuan, daktilitas, pengamatan pola retak dan jenis keruntuhan yang terjadi pada kolom penampang segiempat berongga dengan variasi eksentrisitas beban . Hasil penelitian menunjukkan bahwa kolom beton bertulang berongga yang dimodelkan dengan ATENA yaitu untuk model kolom validasi C1E1, C2E1, C3E1, C4E1, C1E2, C2E2, C3E2, C4E2 mempunyai perbedaan beban maksimum dengan hasil eksperimen secara berturut-turut sebesar 0,32%, 2,22%, 1,61%, 7,74%, 1,25%, 0,65%, 2,63% dan 1,94%, dengan perbedaan kekakuan secara berturut-turut sebesar 18,30%, 21,30%, 23,79%, 31,57%, 15,22%, 22,67%, 21,39% dan 14,41%, dan perbedaan daktilitas secara berturut-turut sebesar 48,71%, 33,64%, 3,39%, 41,04%, 52,30%, 22,99%, 18,11% dan 7,76%. Pola retak yang terjadi adalah pola retak lentur dan retak geser. Pola keruntuhan pada C1E1, C2E1, C3E1, C4E1 merupakan keruntuhan tekan, sedangkan C1E2, C2E2, C3E2, C4E2 merupakan keruntuhan tarik.Kata-Kata kunci: ATENA, berlubang, eksentrisitas, keruntuhan, kolom, nonlinear.REFERENCESCervenka et al. (2007). Superior Material Models for Numerical Simulation of Concrete Cracking under Severe Conditions. Cervenka Consulting. Czech Republic.Public Work Ministry. (2007). SNI 03-2847-2007, Tata Cara Perhitungan Struktur Beton Bertulang untuk Bangunan Gedung. Bandung.Poston et al. (1985). Numerical Models for Non-prismatic Solid Cross-Section Behavior and Rectangular Cross-Section on Biaxially-Bred ColumnsSuprabowo, S. (1996). Analysis of Reinforced Concrete Column Capacity Perforated. Thesis. Department of Civil Engineering, Gadjah Mada University. Yogyakarta.Supriyadi. (1997). The Effect of Holes on Strongly Reinforced Concrete Column Boundaries. Thesis. Graduate Program. Gadjah Mada University. Yogyakarta.Zacoeb. A. (2003). Flexural Capacity of Reinforced Concrete Short Column with Variations Hole, Thesis. Graduate Program. Gadjah Mada University. Yogyakarta.
A NEW METHOD FPR ASSESSING THE RESISTANCE OF A REINFORCED CONCRETE COLUMN WITH A CIRCULAR CROSS SECTION
