PERILAKU RANGKAK SUSUT TERHADAP LENDUTAN STRUKTUR JEMBATAN BENTANG PANJANG

Jembatan Lemah Ireng 1 pada ruas jalan Tol Semarang-Bawen terbuat dari beton prategang dengan panjang total 879 m. Pada masa konstruksi dua perbedaan kondisi teknik terhadap rencana, yakni perubahan material pasir dan perubahan perpindahan traveler. Keduanya diduga sebagai penyebab perbedaan elevasi desain dengan elevasi aktual sehingga dilakukan levelling aspal dengan tebal bervariasi. Jembatan ini didesain untuk memenuhi masa layan 100 tahun namun berdasarkan kondisi aktual, diperlukan peninjauan terhadap perilaku dan kuat layan jembatan hingga umur rencana. Dengan pengaruh variasi pembebanan jangka panjang (rangkak susut) dan kondisi perubahan teknis akibat penambahan aspal, penelitian rangkak susut ini perlu dilakukan untuk mengetahui perilaku lendutan pada gelagar boks jembatan hingga umur rencana. Beberapa tahapan pembebanan yang dilakukan adalah menerapkan beban levelling aspal, dan beban rangkak dan susut dengan menggunakan variasi durasi jangka panjang dengan interval 5, 10 , 15, 20, 40, 60, 80 dan 100 tahun. Analisis dilakukan secara linear statik serta memanfaatkan fasilitas Construction Stage Analysis untuk efek time-dependent pada software Midas Civil 2011. Penelitian ini dilakukan dengan hanya meninjau aksi tetap. Perilaku rangkak susut jembatan cukup signifikan di 5 tahun pertama setelah konstruksi selesai. Lendutan maksimum rangkak susut dan total berada di bentang terpanjang (P4-P5)  masing-masing sebesar 17,53 dan 25,71 cm. Lendutan yang terjadi hingga umur rencana 100 tahun masih dalam batas izin, namun tetap perlu pengawasan yang terencana. Dampak minimum rangkak susut terhadap total lendutan pada jembatan Lemah Ireng 1 sebesar 45%. Hal ini menunjukkan rangkak susut terhadap defleksi total hingga umur rencana merupakan efek jangka panjang yang relatif besar

WAKTU GETAR STRUKTUR BANGUNAN GEDUNG DENGAN PEREDAM GETAR EKSTERNAL FLUID VISCOUS DAMPER

Struktur bangunan tahan gempa menjadi solusi dalam perencanaan struktur. Salah satu  solusi yang digunakan untuk meningkatkan kinerja struktur bangunan adalah dengan pemasangan Fluid Viscous Damper (FVD). Penelitian ini menunjukkan waktu getar struktur dengan penambahan  FVD pada sudut-sudut gedung. Struktur gedung yang dibahas adalah struktur gedung beton bertulang 10 lantai berukuran 35 x 35 m dengan fungsi bangunan sebagai perkantoran. Lokasi penempatan Fluid Viscous Damper (FVD) diaplikasikan pada sudut-sudut bangunan. Kemudian dilakukan pemodelan struktur 3 dimensi dengan bantuan software ETABS 2018.  Pemodelan struktur dibuat dalam 2 model, yaitu struktur rangka dan struktur dengan Fluid Viscous Damper (FVD). Waktu getar alami struktur didapat dengan bantuan program ETABS 2018. Waktu getar struktur yang didapat dari pemodelan struktur tanpa peredam dan struktur dengan Fluid Viscous Damper.  Penggunaan FVD pada struktur gedung memberikan penurunan waktu getar struktur hingga 56% lebih rendah dari sistem struktur rangka pada mode ke-1 dan mode ke-2.  Selanjutnya memberikan penurunan waktu getar struktur hingga 89% untuk mode ke-12. Efektifitas penggunaan damper tipe FVD memberikan dampak secara langsung melalui waktu getar struktur

PREDIKSI KAPASITAS PENAMPANG KOLOM BETON BERTULANG DENGAN VARIASI DIAMETER TULANGAN

Reinforced concrete column design is the process of determining the dimensions of the columns and reinforcement required with the appropriate quality of concrete and steel so that they can withstand the planned load to work on the column. Unlike the beam design, which was based on the applied load, it is possible to determine the cross-sectional dimensions and reinforcement requirements directly from the design equation, and the column design process is iterative. A column generally experiences axial forces, shear forces, bending moments, and torsional moments. In this paper, cross-sections of reinforced concrete columns are modelled and analyzed using an android application that can be installed via the play store. The application offered by eigenplus named RCC Column Design version 2.1.12 was released on 17 September 2017. The last updated RCC Column Design application was on 25 March 2018. This paper aims to predict the cross-sectional capacity of reinforced concrete columns with variations in reinforcement diameter. The cross-sectional capacity of the column referred to in this paper is the axial capacity, moment capacity, and shear capacity. Furthermore, the value of the cross-sectional capacity of reinforced concrete columns with variations in the diameter of the reinforcement has been obtained. The values ​​obtained are proposed as predictions in this paper.Desain kolom beton bertulang adalah proses penentuan dimensi kolom dan tulangan yang dibutuhkan dengan mutu beton dan baja yang sesuai, sehingga dapat menahan beban yang direncanakan bekerja pada kolom. Berbeda dengan desain balok dimana berdasarkan beban yang diberikan, dimungkinkan untuk menentukan dimensi penampang dan kebutuhan tulangan secara langsung dari persamaan desain, proses desain kolom bersifat iteratif. Pada umumnya sebuah kolom mengalami gaya aksial, gaya geser, momen lentur dan momen puntir. Dalam tulisan ini penampang kolom beton bertulang dimodelkan dan dianalisis menggunakan aplikasi android yang dapat diinstal melalui play store. Aplikasi yang ditawarkan oleh eigenplus bernama RCC Column Design versi 2.1.12 dirilis pada tanggal 17 september 2017. Aplikasi RCC Column Design terakhir diupdate pada tanggal 25 maret 2018. Tulisan ini bertujuan untuk memprediksi kapasitas penampang kolom beton bertulang dengan variasi diameter tulangan. Kapasitas penampang kolom yang dimaksud dalam tulisan ini yaitu kapasitas aksial, kapasitas momen dan kapasitas geser. Selanjutnya, nilai kapasitas penampang kolom beton bertulang dengan variasi diameter tulangan telah diperoleh. Nilai-nilai yang diperoleh diusulkan sebagai prediksi dalam tulisan ini. &nbsp

Stress distributions of PSC box girder bridge due to creep shrinkage effect

Long-span bridges are usually designed with a service life of more than 20 years. Thus, it is required to consider factors that are affected by time. Creep and shrinkage are parameters to predict time-dependent behavior of a bridge. The purpose of this study is to determine the effects of creep & shrinkage toward total stresess. Lemah Ireng 1 Bridge in Semarang-Solo toll road was used as a case study. The bridge has a total span length of 879 m. It has a service life design of 100 years. Therefore, this creep and shrinkage research is necessary to determine the stress distribution in the box girder bridge until the end of the service life. Computational modelling was conducted to estimate the stress distribution in the structure of the box girder bridge. Several stages of loading on the bridges were applying asphalt leveling, barrier, creep and shrinkage load by using a variation of the long-term duration with intervals of 5, 10, 15, 20, 40, 60, 80 and 100 years. The analysis was using linear static method, Construction Stage Analysis-Time Dependent effects on Midas Civil and only apply non-transient load on the bridge structure. This study is expected to show the impact of the creep and shrinkage effects of the total stresses along the bridge span until the service life of 100 years

STUDI PERILAKU KUAT GESER BALOK BETON BERTULANG MEMADAT SENDIRI DENGAN SERAT “POLYPROPYLENE”

This paper presents a study of the behavior of self compacting reinforced concrete with polypropylene fiber. Four self compacting reinforecd concrete beam specimens were cast and tested in this study. Two beams were cast without fiber and two beams were cast with polypropylene fiber. The proportion of polypropylene fiber was 0.9 kg/m of the weight of concrete and the proportion of silica fume was 10 % of the weight of portland cement. The dimension of the beam was (180×260) mm with 2000 mm length. Two longitudinal bars with Ø10 mm were placed at the top of the beam as compressive bars and three longitudinal bars with Ø10 mm were placed at the bottom of the beam as tensile bars. Shear reinforcement with Ø8 mm with spacing of 150 mm were placed at the midle, and there were no stirrups at the shear region. Several cylinder specimens with size of (150×300) mm and beam without reinforcement with size of (200×200×700) mm were also cast and tested to determine the mechanics properties of concrete such as compressive strength, tensile strength, modulus of elasticity and modulus of ruptures. The result show that the compressive strength and modulus of elasticity of self compacting concrete with polypropylene fiber were decreased 26.98 % and 9.98 %, respectively compare to the self compacting concrete without fiber. While the tensile strength and modulus of ruptures of the self compacting concrete with polypropylene fiber were increased 2.76 % and 3.65 %, respectively compare to the self compacting concrete without fiber. The shear capacities of the self compacting concrete beams without fiber were 62.76 kN and 63.44 kN. While the shear capacities of the self compacting concrete beams with polypropylene fiber were 60.77 kN and 50.61 kN

Flexural Strength of Self Compacting Fiber Reinforced Concrete Beams using Polypropylene Fiber: an Experimental Study

One of the methods to increase the tensile strength of concrete is adding a fiber mat erial into the concrete. While to reduce a noise in a construction project, a self compacting concrete was a good choices in the project. This paper presents an experimental study of flexural behavior and strength of self compacting fiber reinforced concrete (RC) beams using polypropylene fiber. The micro monofilament polypropylene fibers with the proportion 0.9 kg/m of concrete weight were used in this study. Four beam specimens were cast and tested in this study. Two beams were cast of self compacting reinforced concrete without fiber, and two beams wer e cast of self compacting fiber r einfor ced concret e using polypropylene. The beams specimen had the sect ion of (180×260) mm and the length was 2000 mm. The beams had simple supported with the span of 1800 mm. The longitudinal r einforcements were using diameter of 10 mm. Two reinforcements of Ø10 mm were put for compressive reinforcement and three reinforcements of Ø10 mm were put for tensile reinforcement. The shear reinforcement was using diameter of 8 mm. The shear reinforcements with spacing of 100 mm were put in the one fourth near to the support and the spacing of 150 mm were put in the middle span. Two points loading were used in the testing. The result shows that the load-carrying capacity of the self compacting reinforced concrete beam using polypropylene was a little bit higher than the self compacting reinforced concret e beam without polypropylene. The increment of load-carrying capacity of self compacting polypropylene fiber reinforced concrete was not so significant because the increment was only 2.80 % compare to self compacting non fiber reinforced concrete. And from the load- carr ying capacit y- deflection relationship cur ves show that both the self compacting polypropylene fiber reinforced concret e beam and the self compacting non fiber reinforced concrete beam were ductile beams