NON-LINEAR ANALYSIS OF HOLLOW REINFORCED CONCRETE COLUMN QUARE CROSS-SECTION WITH VARIOUS LOAD ECCENTRICITY AND CONCRETE STRENGTH

Abstract

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, nonlinear

ANALISIS NON-LINEAR KOLOM BETON BERTULANG PENAMPANG SEGIEMPAT BERONGGA DENGAN VARIASI EKSENTRISITAS BEBAN DAN MUTU BETON

Lubang 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.

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