EFEK PENGEKANGAN KOLOM BERLUBANG BETON MUTU NORMAL TERHADAP DAKTILITAS KURVATUR

Abstract

Conduit (pipes) in reinforced concrete columns is still used to date. ACI 318M-95 code limits the hole up to maximum 4% of the column cross sectional area. If the percentage is more than 4%, its effect toward its strength should be considered. But the Code does not mention the effect of the hollow cross section on the ductility. This study was done by testing hollow and solid columns with variation as follows: single stirrup ratio = 0.0184, double stirrup ratio = 0.0276, longitudinal steel ratio = 0.0252, concrete compression strength f’c = 26 MPa, column cross-section b = h = 200 mm, column length L = 1100 mm, hole-ratio (0%, 4.53%, 7.07%). Both ends of the column are loaded by constant axial compression load of 0.12f’cAg = 12,5 ton, lateral loads are applied at 1/3 and 2/3 points to produce moments. The observed variables are moment and curvature ductility. The result of the study shows that the 4% hollow column still has the same moment strength as the solid one. This experiment also indicates that its curvature ductility is within the range of 6.14    8.49, thus showing that the columns should be considered as limited ductile structure. If the hole-ratio is more than 4%, however, a decrease in the curvature ductility will be found. Abstract in Bahasa Indonesia : Sampai saat ini masih ditemui pemakaian konduit (pipa-pipa) pada kolom beton bertulang, sehingga penampang kolom menjadi berlubang. Peraturan ACI 318M-95 membatasi besarnya lubang maksimum 4%, apabila persentase lubang  4%, maka besarnya lubang harus diperhitungkan terhadap pengaruh kekuatannya. Peraturan tersebut tidak menyinggung pengaruh lubang terhadap daktilitas kolom berlubang. Penelitian ini dilakukan dengan membuat benda uji kolom berlubang dan tak berlubang dengan variasi: rasio sengkang tunggal = 0,0184; rasio sengkang rangkap = 0,0276; rasio tulangan memanjang = 0,0252; f’c = 26 MPa, penampang kolom = b x h = 200 mm x 200 mm, panjang kolom = L = 1100 mm, rasio lubang (0%; 4,53%; 7,07%), pada kedua ujung kolom diberikan Paksial-tekan konstan 0,12f’cAg = 12,5 ton, diberikan pula beban lateral terletak 1/3 & 2/3 bentang kolom untuk menimbulkan momen. Variabel yang diamati berupa momen dan daktilitas kurvatur. Hasil penelitian tentang kekuatan momen kolom berlubang 4% masih menunjukkan kekuatan yang sama dengan kolom tak berlubang. Eksperimen ini juga mendapatkan daktilitas kurvatur rentang 6,14,8,49 (termasuk daktilitas terbatas). Jika rasio lubang melebihi 4%, maka akan menurunkan daktilitas kurvatur

Keywords

• hole ratio
• curvature ductility
• limited ductility.