Civil Engineering Dimension (E-Journal)
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Experimental Investigation on the Effect of Specimen Size in Determining Fracture Parameters of Concrete
Get PDFThis paper presents the experimental results in investigating the effect of specimen size (ratio of beam width to aggregate size) on the value of stress intensity factor (KIC) and fracture energy (GF) using three-point bend (TPB). A test method recommended by RILEM was chosen to measure the KIC and the GF as fracture parameters. Three different specimen sizes of concrete beam with water/binder ratio of 0.2 and 0.30 were engaged in the experiments. Both qualitative and quantitative analyses based on the normalized stress against deflection curve, and the KIC and the GF were employed. Statistical analysis was carried out based on coefficient of variation of the measured value of fracture parameters in order to investigate the variability of corresponding results. It was found that specimen size have a relatively insensitive influence on the value of KIC, however, have a significant effect on the value of GF
Reinforced Concrete Finite Element Modeling based on the Discrete Crack Approach
Get PDFThe behavior of reinforced concrete elements is complex due to the nature of the concrete that is weak in tension. Among these complex issues are the initial cracking and crack propagation of concrete, and the bond-slip phenomenon between the concrete and reinforcing steel. Laboratory tested specimens are not only costly, but are limited in number. Therefore a finite element analysis is favored in combination to experimental data. The finite element technique involving the cracks inserting is one of the approaches to study the behavior of reinforced concrete structures through numerical simulation. In finite element modeling, the cracks can be represented by either smeared or discrete crack. The discrete crack method has its potential to include strain discontinuity within the structure. A finite element model (FEM) including the concrete cracking and the bond-slip was developed to simulate the nonlinear response of reinforced concrete structures
Proposed Design Graphs of Geotextile Reinforcement on Soft Clay under Various Field Conditions
Get PDFThis paper describes the behavior of reinforced embankments constructed on soft clay subgrade with varying compressible depths, embankment slopes and embankment heights. The stability of the embankment is evaluated using the Bishop method. The resistance moment and the numbers of geotextiles required are examined. It is shown that varying the subgrade and embankment can significantly affect the embankment stability and also the number of reinforcements. It requires a lot of time to design embankment reinforcements, especially when the length of the embankment is tens of kilometers. The main aim of this study is to develop graphs to assist in designing the number of geotextile reinforcements. This paper proposes design graphs to support engineers and designers to determine the required geotextile reinforcements for embankments
The Characteristics of Asphalt Concrete Binder Course (AC-BC) Mixture with Bottom Ash as Aggregate Substitute
Get PDFHighways serve nearly 80-90% of the population mobility and flow of goods. Utilization of bottom ash, a waste from coal combustion, in highway construction is one of the alternatives to reduce environmental pollution and support Clean Development Mechanism Program of Kyoto Protocol. The aim of this study is to analyze the characteristics of AC-BC mixture that uses bottom ash as partial substitute of fine aggregate and comparing with a standard mixture. Laboratory tests are performed on two different types of mixtures. The tests show that optimum asphalt content for AC-BCStandard mixture is 5.20% while AC-BCBottom Ash mixture is 5.25%. Bottom ash has higher porosity along with a little break field and has round shape so that the asphalt absorption is bigger than the crushed stone. Bottom ash can be used as an alternative aggregate to increase the value of flow of the AC-BC mixture, thus converting waste to valuable material
Characteristics of Bamboo Leaf Ash Blended Cement Paste and Mortar
Get PDFThe use of bamboo leaf ash as cement supplement can contribute to reduction in cost and environmental hazard associated with cement production as well as waste pollution caused by the littered bamboo leaves. Therefore, the characteristics of cement paste and mortar incorporating bamboo leaf ash were investigated. The results of the physical properties of the pastes were within the requirements stipulated by relevant standards while that of the mortar cubes indicated that the compressive strength generally increased with curing age, and that the mix containing 15% Bamboo Leaf Ash (BLA) by mass competes favorably with that of the reference mix at 28days and above. The water absorption and apparent porosity were observed to increase with increase in BLA content, while the bulk density decreases as the percentage of BLA increases from 5% to 25% by mass. The study concluded that 15% BLA replacing cement is adequate for the production of masonry mortar
Experimental and Theoretical Analysis of Hollow Steel Columns Strengthening by CFRP
Get PDFThe need for strengthening and retrofitting is well known and extensive research is progressing in this field. The reasons for strengthening and retrofitting are numerous: increased loads, changes in use, deterioration, and so on. In recent years, the use of carbon fiber reinforced polymer (CFRP) for strengthening has shown to be a competitive method, both regarding structural performance, and economical aspects. Extensive research has been carried out in this field. However, most of the research has been undertaken on concrete structures and for confinement, flexural, and shear strengthening. Limited research has been carried out on steel structures strengthened with CFRP. This paper presents axially loaded steel columns strengthened for increased load. The topic is studied theoretically and through laboratory tests. The theory covers analytical methods. Carbon fiber reinforced polymers has been used to strengthen the columns. The tests have been undertaken on full scale specimens, non-strengthened for reference, partially strengthened and fully strengthene
Community-Based Approach in A Small Scale Irrigation Project in Indonesia: Ways and Advantages
Get PDFThe implementation of community-based approach, where community can control a government owned infrastructure project, is rarely found. However, Sumatra River Basin Organization (BWSS) V successfully implemented a small scale irrigation project using this method in West Sumatra Province, Indonesia. This paper aims to describe how this policy was implemented, highlight its milestones, and discuss the advantages of its application. A detailed literature review and semi structured interviews were conducted to achieve the objectives. It was found that the implementation of community-based approach can bring about a sense of belonging, sustainability, and a source of income for the community. Hence, the project was finished on time within budget with high quality materials. In some cases the quantity of the project was more than it was targeted. The key policy that contributed to the success was trusting community to control the project and making sure that the proposed project came from the community
Prediction of Crack Width Due to Corrosion of PC Tendon in Prestressed Concrete Structures
Get PDFCorrosion expansion of prestressed concrete (PC) tendon affects mainly crack width on surface of concrete. This paper simulates corrosion expansion of PC tendon in concrete. Elastic expansion model is utilized for growing of corrosive product as a result of oxidation reaction on reinforcement. In reality, corrosive product penetrate freely into concrete. In order to cover this behavior, elastic expansion is then enhanced its capability in numerical simulation. Furthermore the proposed model used an apparent expansion is adopted to predict width of corrosion crack. Laboratory test is conducted to verify numerical result. Single and multi PC tendons embedded in concrete attacked by corrosion is investigated. Finally, prediction of crack width on surface of concrete due to corrosion of multi layers of PC tendons in the real pretensioned PC girder are conducted using the proposed model. The results show that corrosion crack width of the proposed model meets the real pretensione
Generalization of FEM Using Node-Based Shape Functions
Get PDFIn standard FEM, the stiffness of an element is exclusively influenced by nodes associated with the element via its element-based shape functions. In this paper, the authors present a method that can be viewed as a generalization of FEM for which the influence of a node is not limited by a hat function around the node. Shape functions over an element can be interpolated over a predefined set of nodes around the element. These node-based shape functions employ Kriging Interpolations commonly found in geostatistical technique. In this study, a set of influencing nodes are covered by surrounding layers of elements defined as its domain of influence (DOI). Thus, the element stiffness is influenced by not only the element nodes, but also satellite nodes outside the element. In a special case with zero satellite nodes, the method is specialized to the conventional FEM. This method is referred to as Node-Based Kriging FEM or K-FEM. The K-FEM has been tested on 2D elastostatic, Reissner-Mindlin’s plate and shell problems. In all cases, exceptionally accurate displacement and stress fields can be achieved with relatively coarse meshes. In addition, the same set of Kringing shape functions can be used to interpolate the mesh geometry. This property is very useful for representing the curved geometry of shells. The distinctive advantage of the K-FEM is its inheritance of the computational procedure of FEM. Any existing FE code can be easily extended to K-FEM; thus, it has a higher chance to be accepted in practice
Characteristics of Motorcycle Ownership and Use of University Students in Malaysian and Indonesian Cities
Get PDFMotorcycle ownership and use increased rapidly in Indonesian cities in recent years. People could not cope with severe congestion due to unsatisfactory public transport and uncontrolled land use delopment. This led to motorcycle use for almost any trip. However, in Malaysia motorcycles were mainly used for local short distance travel. In this paper the characteristics of motorcycle ownership and use of university students in Malaysian and Indonesian cities were discussed. A total of 398 university students in eight cities were asked to fill the questionnaires. They consist of general questions regarding their socio-economic back-ground and travel habit along with 25 perceptional questions regarding affordability/ attractiveness of owning motorcycle and practicability/safety of motorcycle use. A variance based structural equation modelling called partial least square-path modelling (PLS-PM) was used for analysis. The results show that indicators explaining affordability and acceptability were exactly the same in Penang and combination of seven cities in Indonesia