1,720,972 research outputs found
PENGUKURAN KOEFISIEN AERODINAMIS MODEL-MODEL JEMBATAN BENTANG PANJANG
Full text linkThe objective of this research is to measure aerodynamic coefficients of long-span bridge deck models. Four
models with different wind nose (fairings) will be tested using open loop wind tunnel. These replicas are
made from glass fiber as major material. Flow-field dynamic similarity is maintained through nondimensional
number such as Reynolds number. Determination of aerodynamic coefficients was carried out
using balance method whereas aerodynamics forces are measured by strain gages based balance apparatus.
The result is presented on graphics of lift coefficient (CL), aerodynamic moment coefficient (CM) and coefficient
of drag (CD) as function of angle of attack (a)
THE PREDICTION OF LONG -TERM SHRINKAGE OF LIGHTWEIGHT CONCRETE CONSIDERED TO MAGNITUDE OF SHORT - TERM SHRINKAGE PREDIKSI SUSUT JANGKA PANJANG BETON RINGAN BERDASAR NILAI SUSUT JANGKA PENDEK
Full text linkThe magnitude of long-term shrinkage of lightweight concrete has to be considered in the design of lightweight concrete structure. This research is intended to develop a model for predicting the maginitude of long-term shrinkage of lightweight concrete based on the short-term value. Model of ACI 209 R-92 is used as a reference to start with and then it is verified and modified with the results of more than 9 months shrinkage observation on samples of lightweight concrete having various degrees of saturation of Artificial Lightweight Aggregate (ALWA), water/cement ratios, volume/surface ratios and curing period. The final model may be applied to predict long-term shrinkage of lightweight concrete using data from the observation of shrinkage for 28 days only. Coefficient error of prediction is about 30%
Keywords: lightweight concrete, model, prediction, shrinkage
Nilai susut jangka panjang dari beton ringan harus diperhitungkan dalam perencanaan struktur beton ringan. Penelitian ini fokus pada pengembangan model prediksi susut jangka panjang beton ringan berdasar nilai susut jangka pendek. Model ACI 209 R-92 digunakan sebagai referensi untuk memulai dan kemudian diverifikasi dan dimodifikasi dengan hasil lebih dari 9 bulan observasi sample susut jangka panjang beton ringan dengan derajat kejenuhan agregeat buatan ringan (Artificial Lightweight Aggregate, ALWA), kadar air dan semen, rasio volume/permukaan, dan waktu perawatan yang berbeda-beda. Model terakhir mungkin bisa dipakai untuk memperkirakan susut jangka panjang beton ringan dengan menggunakan data observasi susut selama 28 hari saja. Angka kesalahan dari prediksi ini sebesar 30%.
Kata-kata kunci: beton ringan, model, prediksi, susu
PENGARUH FAKTOR LINGKUNGAN INTERNAL DAN AGRESIF TERHADAP KOLOM RETROFIT DENGAN CFRP DAN GFRP
Full text linkThe strengthening technique to retrofit a reinforced concrete structure is an effective strategy to enhance the local and global structure capacity. It could be the structure's strength, stiffness, and failure resistance. The retrofit strategy is selected in the wrapped column method using FRP (Fiber Reinforced Polymer). This study analyzed one column element using the static nonlinear procedure to determine the member of the structure toward seismic forces. The rectangular column was analyzed using Adaptive Pushover Analysis. This procedure operates the not constant lateral load, then attaining more realistic results by displacement-based inelastic element type. Three models were analyzed using Seismostruct with the non-retrofit column without FRP and two models with retrofitted FRP by carbon or CRFP and glass or GFRP. Those two materials have advantages under different conditions, so that this enhancement can install under different risks and circumstances. The column capacity increase wrapping CFRP reached more than 10 % compared with the non-retrofit column. Wrapping GFRP represents that column capacity failure resistance is more significant than CFRP in internal and aggressive environment types
Model dan Pendekatan Fuzzy LogicUntuk Program Pemeliharaan Jembatan Beton
Full text linkEvaluation of the existing condition of the bridge is the most important part of the
bridge maintenance program and is still often depend to a very large degree on the
experience, judgment and bridge engineers flexibility, so that resulted to a serious
problem due to the nature of subjectivity of assessment. In the process of decision
making to determine the type of repairs needed for concrete bridges, one of the key
parameter is the condition rating. The reliability of these parameters depends on the
reliability and accuracy of information provided bybridge inspectors, who are often
influenced imprecision and opinions (biased) personal. Therefore it is necessary to
provide a systematic procedure to reduce this weakness.
Fuzzy logic provides a natural way to deal with problems that do not have a source of
precision in the absence of sharply defined criteria of a class (class) set membership.
The set itself is a class of fuzzy objects with membership that has a continuum of
gradations (continuum of grades of membership). In the process of bridge inspection,
inspectors often must assess the level of severity (severity) of a visual defect with
"severe" or "not severe". On the set of non-fuzzy space inspectors is only one
response among the above conditions, if the answer is not "severe", yes of course "not
severe " is the answer. But in the fuzzy space possible for inspectors to quantify the
level of significance between "severe" to "not severe" with a numerical value
(numerical rating).
Expert System is a system that tries to provide answers to the problem, or clarify the
uncertainty which is usually one or more human experts would need to consult.
Compared to traditional programming techniques, expert-system approaches provide
the added flexibility (and hence easier modifiability) that arises from the ability to
model rules as data rather than as code.
The resulting software can be a cost - time-effective rapid information for technical
evaluation jembatatan maintenance of reinforced concrete. Simultaneously, this
software can give recommendations and / or second opinion to support the executive
decisions jembatatan maintenance of reinforced concrete
WATER WITHIN LIGHTWEIGHT AGGREGATE CONCRETE AND ITS RELATION TO AUTOGENOUS SHRINKAGE
Full text linkAbstract
Autogenous shrinkage of lightweight aggregate concrete (LAC) has been investigated with the aims of studying if water
within LAC is effective in preventing autogenous shrinkage as suggested by Bentz’s model. By calculating ratios of water
supplied by lightweight aggregate (LA) at various degrees of saturation to water required for maximum hydration
and plotting these against ultimate values of autogenous shrinkage, it seems that only when the ratio is high (above 3.5)
then the water within LAC supplied from LA is immediately ready to fill the empty pores and in turn, reducing autogenous
shrinkage. The case is also confirmed when ratios of total void (porosity) of concrete to total volume of water
within concrete are plotted against autogenous shrinkage.
Keywords:
autogenous shrinkage, Bentz’s model, lightweight aggregate, porosity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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