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"Concrete is a favoured building material due to its ease of production and use. Even though the concrete mix is designed to have a uniform strength throughout the entire member, casting, as well as the basic characteristics of the concrete materials, could yield a non-homogeneous constitution, resulting in a concrete strength gradation as a function of the depth of the member. A functionally continuous and smooth strength gradation of the concrete member along its axis or section is defined as graded concrete. The objective of this research is to analyse the influence of two different concrete compressive strengths that composed the graded concrete member. The study is split into two parts: the experimental work describing and identifying the mechanical properties of functionally graded concrete and the finite element analysis implementing these property variations in a model. The results showed that the concrete gradation influenced the ultimate strength of a member negatively and altered the stress distribution and displacement response of the specimen."

"Concreteis a favoured building material due to its ease of productionand use. Even though the concrete mix isdesigned to have a uniform strength throughout the entire member, casting, aswell as the basic characteristics of the concrete materials, could yield anon-homogeneous constitution, resulting in a concrete strength gradation as afunction of the depth of the member. A functionally continuous and smooth strengthgradation of the concrete member along its axis or section is defined as gradedconcrete. The objective of this researchis to analyse the influence of two different concrete compressivestrengths that composed the gradedconcrete member. Thestudy is split into two parts: theexperimental work describing and identifying the mechanical properties offunctionally graded concrete and the finite element analysis implementing theseproperty variations in a model. The results showed that the concrete gradationinfluenced the ultimate strength of a member negatively and altered the stressdistribution and displacement response of the specimen."

"Concrete is a composite building material. Due to its increasing demand in the construction industry, its basic ingredients such as cement, fine aggregate and coarse aggregate have become extremely costly. Studies have been carried out to find better and more economical alternatives to these conventional building materials. One such alternative is fly ash, which can be used to partially replace cement. The main disadvantage of conventional concrete is its brittle failure, which can be avoided by using steel fibers. This study identifies the behavior of concrete with regard to impact resistance and its mechanical properties by adding hooked-end steel fibers at levels of 0, 0.75, 1.15 and 1.55% and partially replacing 40% of the cement with 40% fly ash. In addition to the control concrete, there has been four mixes with respective addition of steel fibers. The behavior of normal and fly ash concrete with steel fibers was compared. The combination of fly ash and steel fibers provided a homogeneous and very rich mix, with a delay in the setting time of the concrete. Of all the mixes, the one containing 40% fly ash and 1.55% steel fibers proved to be the best, with a maximum increase in strength of 17% in compression, 25% in split tension, 30% in flexure and 95% in impact energy at 56 days. A multiple linear regression model was also formulated using SPSS (Statistical Package for Social Sciences) software, through which corresponding equations were developed to predict the strength and energy at 28 and 56 days. The equations were also used to predict the strength of the mixes from other researchers’ experimental work. The predicted results corresponded well with the experimental results and the percentage difference was found to be less than 5%."

"Pemanfaatan potensi bahan bangunan lokal berupa limbah batu bara dalam pembuatan bahan bangunan ekologis menjadi salah satu bentuk dukungan terhadap konsep konstruksi ramah lingkungan."

"Perkembangan teknologi engineering tidak lagi hanya berupa analisa dan evaluasi yang didasarkan dari aspek teknis saja, namun mulai diperhatikan latar belakang akan akibatnya pada kondisi lingkungan. Permasalahan kerusakan alam yang diakibatkan oleh penambangan batuan yang berlebihan dan pembuangan limbah beton tersebut dapat dikurangi dengan cara memanfaatkan atau mendaur ulang limbah beton sebagai agregat alternatif. Namun, pemanfaatan limbah sebagai agregat daur ulang tersebut perlu dikaji lebih mendalam, dengan melakukan pengujian eksperimental dan analisis terhadap karakteristik yang dimiliki, yaitu dengan melakukan penelitian terhadap material daur ulang dan dibandingkan dengan penelitian terhadap agregat alam sehingga dapat diperkirakan sejauh mana agregat daur ulang ini dapat digunakan sebagai bahan pembuat beton. Selanjutnya dilakukan pembuatan sampel beton dengan delapan komposisi agregat daur ulang agregat alam, dengan target strength yang direncanakan adalah 25MPa. Kemudian dilakukan penelitian terhadap kuat tekan dan kuat tarik belahnya. Metode dan prosedur pelaksanaan pengujian tersebut dilakukan dengan mengacu pada standar ASTM. Berdasarkan hasil pengujian agregat halus daur ulang, terdapat kandungan semen yang cukup tinggi, yang apabila dilihat dari analisa saringan, terdapat 6,27% partikel yang lolos hingga pan dimana partikel ini merupakan sisa pasta semen. Sedangkan hasil pengujian agregat kasar daur ulang menunjukkan tingkat absorpsi yang mencapai 13,67% dan tingkat keausan yang mencapai 41,22%. Beberapa perbedaan kualitas serta sifat-sifat fisik dari agregat daur ulang tersebut menyebabkan perbedaan sifat-sifat material beton yang dihasilkan. Dari hasil pengujian terhadap beton yang telah mengeras, perbedaan yang terjadi diantaranya adalah menurunnya kuat tekan, kuat tarik belah, dan modulus elastisitasnya seiring dengan penambahan rasio agregat daur ulangnya, baik agregat kasar daur ulang maupun agregat halus daur ulang. Besarnya persentase agregat kasar daur ulang yang dapat menghasilkan beton dengan kuat tekan memenuhi target strength adalah 25%. Sedangkan besarnya persentase agregat halus daur ulang yang dapat menghasilkan beton dengan kuat tekan memenuhi target strength juga 25%.

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Nowadays, the development of engineering technology is not just based on the analysis and evaluation from technical aspects only, but also concerning the impact to the environment. Concrete, as the main material on building construction, are produced using many kinds of material taken from the natural site, so on years after, this production will lead into an environmental crisis. The environmental problem caused by the quarry of aggregate and the dumping of concrete waste could be reduced by using and recycling the concrete waste to be an alternative aggregate. But then, the using of concrete waste as a recycled aggregate should be evaluated more with experimental and analytical study which is to do research on recycled material and then compare it with the natural one so that it could estimate on how much this recycled aggregate could be useful as a material for producing concrete. Next step is to make samples with eight compositions of recycled-natural aggregate with the target strength of 25MPa. After that is doing the test on its compressive strength and splitting tensile strength. Method and procedure of the research are based on ASTM standards.

Based on the research of fine recycled aggregate, there is a quite high amount of cement, which could be seen from the Sieve Analysis, there is 6,27% constituent part that passed until pan, which this passing constituent is the cement. From the research on coarse recycled aggregate, the amount of absorption is 13,67% and from abrasion test with Los Angeles Machine, the aggregate abraded until 41,22%. These differences in quality and physic properties produce different kind of concrete. This difference could be seen from its degradation in compressive strength, splitting tensile strength, and modulus of elasticity. The amount percentage of recycled coarse aggregate that could be used to gain compressive strength fulfills the target strength is 25%. Also, the amount of recycled fine aggregate that could perform as the target strength is 25%."

"ABSTRAKPada penelitian kali ini akan diteliti struktur komposit yang dikenal dengan istilah Concrete Filled Steel Tube (CFST) yaitu struktur baja hollow kotak yang diisi dengan beton. Struktur ini sudah secara luas dipakai dalam bidang konstruksi diantaranya adalah sebagai balok girder jembatan kereta api yang terdapat di Jepang (Hosaka et al., 1997; Nakamura et al., 2004). Beberapa keuntungan dari struktur CFST antara lain adalah struktur memiliki daktilitas yang tinggi jika dibandingkan dengan struktur beton bertulang biasa, penampang beton dapat mencegah terjadinya local buckling pada penampang hollow baja dan sebaliknya penampang baja dapat menjaga confinement struktur beton sehingga beton dapat meningkatkan kekuatannya. Tujuan dari penelitian ini adalah melakukan analisa perilaku struktur komposit CFST dengan memodelkan struktur secara matriks dan melakukan permodelan fiber model pada penampang balok. Analisa yang dilakukan mencakup analisa perilaku linear dan non-linear penampang, analisa kekakuan sambungan dan kapasitas sambungan. Proses analisa dilakukan dengan membandingkan grafik eksperimen dan grafik hasil permodelan. Hasil penelitian menunjukan bahwa grafik hasil eksperimen mendekati grafik permodelan, dan sambungan memiliki sifat kekakuan yang rigid dan kapasitas yang cukup besar sehingga sambungan tetap elastis pada saat balok mengalami leleh.

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ABSTRACTThis research will investigate composite structure that has known as concrete filled steel tube (CFST), steel hollow cross section fill in with concrete. This type of structure has been widely use in construction site, one of them is use as train?s bridge girder in Japan (Hosaka et al., 1997; Nakamura et al., 2004). Some of the advantages of CFST are this structure has a high ductility if we compare it with common concrete reinforcement, concrete cross section will prevent steel tube to occurrence of local buckling, and on the other hand steel will confine the concrete so it will increase strength of concrete it self. The aim of this research is to analyze the behavior of CFST?s structure by modelling it in stiffness matrix and modelling fiber to beam cross section. The analysis are including behavior of linear and non-linear of beam cross section, connection stiffness, and connection capacity. The analyzing process do by compare the graphic of experiment and the graphic of modelling results. This research show that experiment?s graphics are close to the graphic of modelling result, and connection has rigid stiffness and has enough strength to keep linear while beam has yielding. "

"Penggunaan sumber daya alam sebagai pembuat beton semakin meningkat belakangan ini sehingga menambah jumlah limbah beton. Penelitian ini akan menggunakan agregat kasar dan agregat halus daur ulang sebagai agregat pada beton. Komposisi benda uji terdiri dari 40% agregat kasar daur ulang dan 0%, 20%, 40% dan 60% agregat halus daur ulang dari limbah beton mutu K350-K400. Pengujian meliputi pengujian kuat tekan, kuat lentur, dan susut pada beton. Kuat tekan beton pada komposisi 20% agregat halus daur ulang meningkat 5,18% dari beton normal pada umur 28 hari. Kuat lentur beton dengan komposisi agregat halus daur ulang 20% memiliki nilai yang paling tinggi dibandingkan komposisi lainnya. Susut beton dengan komposisi 60% agregat halus daur ulang mempunyai nilai susut tertinggi dibandingkan dengan komposisi lainnya.

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The using of natural resources to make concrete is increase nowadays that can gain the concrete waste. This study will use fine and coarse recycle aggregate as aggregate as aggregate in concrete. The composition of the test object consisting of 40% coarse recycle aggregate and 0%, 20% 40%, and 60% fine recycle aggregate from concrete waste K350-K400. Testing includes, compressive strength test, flexural strength, and shrinkage in concrete. The purpose of this study is to know the influence of coarse and fine recycle aggregate to compressive strength, flexural strength, and shrinkage in concrete and the optimum composition of the fine recycle aggregate to be used. Compressive strength of concrete with 20% recycled fine aggregate increased by 5,18% of the normal concrete at 28 days. Flexural strength of concrete with 20% recycled fine aggregate has the highest value than other composition. Shrinkage of concrete with 60% recycled fine aggregate has the highest shrinkage value compared to other composition."

"The book consists of two parts. The first part provides basic information about normal concrete, its grades used on sites and various kinds of modified concretes such as fiber-reinforced concrete, sulphur concrete, roller compacted concrete, high performance concrete, ultra- high performance concrete, and flowing concrete. . It further addresses physical properties of concrete and various types of Portland cement, blended cements, admixtures, additives including properties of aggregates and their influence. The second part of the book highlights the principal causes of concrete deterioration along with protective measures, resulting from incorrect selection of constituent materials, poor construction methods, external factors, chemical attack, corrosion problems, hot and cold weather effects, and the various errors in designing and detailing. Featuring an extensive bibliography of the highly adopted standards as well as manuals and journals critical to the construction industry at the end of each chapter, the volume offers readers an advanced understanding of the theory and practical application of concrete technology and international standards in North America and Britain."

"This textbook imparts a firm understanding of the behavior of prestressed concrete and how it relates to design based on the 2014 ACI Building Code. It presents the fundamental behavior of prestressed concrete and then adapts this to the design of structures. The book focuses on prestressed concrete members including slabs, beams, and axially loaded members and provides computational examples to support current design practice along with practical information related to details and construction with prestressed concrete. It illustrates concepts and calculations with Mathcad and EXCEL worksheets. "

"Sebagai negara kepulauan yang rawan terkena bencana alam gempa bumi, perencanaan dan desain gedung bertingkat di indonesia, harus bersifat daktail. Dalam sistem penahan gaya lateral akibat gempa pada suatu struktur beton bertulang, terdapat tiga jenis struktur penahan gaya lateral yaitu Sistem rangka pemikul momen biasa (SRPMB), Sistem rangka pemikul momen menengah (SRPMM), dan Sistem rangka pemikul momen khusus (SRPMK). Penelitian ini dilakukan terhadap SRPMK yang merupakan salah satu tingkat dari moment resisting frame (MRF) dalam bangunan beton.Kerusakan pada struktur dapat dinilai dari penurunan kekakuan struktur. Frekuensi alami merupakan parameter dari fungsi kekakuan yang dapat mengilustrasikan kerusakan pada struktur tersebut. Damage Index merupakan parameter yang dapat menilai kerusakan pada struktur secara kuantitatif. Damage index merupakan fungsi dari deformasi struktur, yang juga dapat mengilustrasikan kerusakan dari struktur dengan baik.Penelitian ini dibagi menjadi dua bagian, yakni pertama merupakan perhitungan damage index dengan membuar kurva pushover monotonik dan semisiklik menggunakan CAST3M. Bagian kedua adalah mencari frekuensi alami struktur dengan menggunakan SAP2000. Penelitian ini menggunakan studi kasus struktur yang berbeda lantai serta bentang dengan properti material yang berbeda.Hasil dari penelitian menyimpulan dengan bertambahnya gaya pembebanan lateral terhadap struktur, nilai frekuensi alami akan mengalami penurunan sedangkan nilai damage index akan mengalami kenaikan."