Civil Engineering Dimension (E-Journal)
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EVALUATING AND IMPROVING THE PERFORMANCE OF COLD ASPHALT EMULSION MIXES
Get PDFThis paper describes investigation on the performances of cold asphalt emulsion mixes (CAEMs). The type of emulsion used was a cationic asphalt emulsion. The investigation was carried out at Leeds University, United Kingdom (UK). The objective of the experiments was to evaluate and to improve the performances of cold mixes and compared with hot mixes. For optimising the performances of the cold mixes, a target porosity of five to ten percent and indirect tensile stiffness modulus (ITSM) value of 2000 MPa was selected, suitable for low to medium trafficked roads. A simplified mix design procedure was used for producing the cold mixes. It was found that when properly designed, at full curing conditions, the stiffness (ITSM) of CAEMs were found to be very comparable to those of hot mixes. Test results also show that the addition of cement in the amount of one to two percent by mass of aggregates significantly improved the mechanical performance of cold asphalt mixes
Derivation Of Moving Least-Squares Approximation Shape Functions And Its Derivatives Using The Exponential Weight Function
Get PDFIn recent years, meshless methods have gained their popularity, mainly due to the fact that absolutely no elements are required to discretize the problem domain. This is possible due to the nature of the approximation functions used in this method. Approximation functions used to form the shape functions use only the so-called “nodal selection” procedure without the need of elements definition. The most popular approximation function used is the moving least-squares shape functions. Published works in meshless methods, however, present only the basic formulas of the moving least-squares shape functions. This paper presents the complete and detailed derivations of not only the moving least-squares shape functions, but also their derivatives (up to the second order derivatives), using the exponential weight function. The derivations are then programmed and verified
METHODOLOGY OF SITE-SPECIFIC SEISMIC HAZARD ANALYSIS FOR IMPORTANT CIVIL STRUCTURE
Get PDFNote from the Editor
The Indonesian archipelago is one of the most active tectonic zones in the world. Therefore to design an important (and dangerous) structure such as a nuclear power plan knowledge of the seismicity of the site is very important. This could be achieved by doing a site-specific seismic hazard analysis. A site-specific seismic hazard analysis is required in the design state in order to determine the recommended seismic design criteria of the structure. A complete and thorough explanation of the methodology to do a site-specific seismic hazard analysis is presented in this Technical Note
Abstract in Bahasa Indonesia
Exploring Public Perception of Paratransit Service Using Binomial Logistic Regression
Get PDFKnowledge of the market is a requirement for a successful provision of public transportation. This study aims to explore public perception of paratransit service, as represented by the user and non-user of paratransit. The analysis has been conducted based on the public’s response, by creating several binomial logistic regression models using the public perception of the quality of service, quality of car, quality of driver, and fare. These models illustrate the characteristics and important variables to establish whether the public will use more paratransit in the future once improvements will have been made. Moreover, several models are developed to explore public perception in order to find out whether they agree to the replacement of paratransit with other types of transportation modes. All models are well fitting. These models are able to explain the respondents’ characteristics and to reveal their actual perception of the operation of paratransit. This study provides a useful tool to know the market in greater depth
A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks
Get PDFThis paper presents the results of experimental investigations carried out on partial replacement of sand with laterite as it affects the compressive strength of sandcrete hollow blocks. Two mix proportions (1:6 and 1:8) were used with laterite content varying between 0 and 50% at 10% intervals. Hand and machine compaction methods were used. Curing was done by sprinkling water on the specimens. The results showed that for each mix proportion and compaction method, the compressive strength decreases with increase in laterite content. Machine compacted hollow sandcrete blocks made from mix ratio 1:6 and with up to 10% laterite content is found suitable and hence recommended for building construction having attained a 28-day compressive strength of 2.07N/mm2 as required by the Nigerian Standards
Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure
Get PDFThe Spectral Analysis of Surface Wave (SASW) method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus) and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-D models are used in the simulation of the inversion process for best fitting between theoretical and empirical dispersion curves. The objective of this study is to simulate and compare the 2-D and 3-D model of SASW analysis in the construction of the theoretical dispersion curve for pavement structure evaluation. The result showed that the dispersion curve from the 3-D model was similar with the dispersion curve of the actual pavement profile compared to the 2-D model. The wave velocity profiles also showed that the 3-D model used in the SASW analysis is able to detect all the distinct layers of flexible pavement units
A Modal Pushover Analysis on Multi-Span Concrete Bridges to Estimate Inelastic Seismic Responses
Get PDFThe performance of Modal Pushover Analysis (MPA) in predicting the inelastic seismic response of multi-span concrete bridges is investigated. The bridge is subjected to lateral forces distributed proportionally over the span of the bridge in accordance to the product of mass and displaced shape. The bridge is pushed up to the target displacement determined from the peak displacement of the nth mode inelastic Single Degree of Freedom System derived from Uncoupled Modal Response History Analysis (UMRHA). The peak response from each mode is combined using Square-Root of Sum-of-Square (SRSS) rule. Although the use of SRSS rule is not appropriate in this bridge and the displaced pattern is shifted from the elastic shape due to yielding, MPA can predict well the total peak response of the bridge in inelastic range
IMPROVING MARINE CLAYS WITH ELECTROKINETICS METHOD
Get PDFThe high water content in marine clays could loosen the bond of soil particles, resulting in low bearing capacity and high compressibility of the soil. Excessive settlements could happened to the structures built on it. An electrokinetic process was attempted to reduce the high water content of the marine clay. An experimental study was conducted to evaluate the effect of electrokinetic on marine clay improvement. This study focused on the use of electrokinetic to enhance the soil bearing capacity of marine clay by improving index properties of the marine clay. The result of this research was obtained by doing several analyses on water content, pH value, and soil particles of soil sample located between cathode and anode. Based on the results from laboratory testing, it can be concluded that electrokinetic process decreased the water content and pH value of soil surrounding the anode. Also, soil particles surrounding the anode became in close proximity. This indicated that as it became closer to the anode, soil became denser
ANALISIS KONSERVASI ENERGI MELALUI SELUBUNG BANGUNAN
Get PDFVentilating and Air Conditioning system consumes 50-70% of the total energy used in an office building. The cooling load of a building consists of internal cooling load, i.e. loads produce by light, occupants, and heat generating power/appliances; and external cooling load, i.e. loads produce by radiation, conduction, and ventilation/infiltration through building envelope. To reduce the external cooling load, SNI 03-6389-2000 specifies that the Overall Thermal Transfer Value (OTTV) should be less than or equal to 45 Watt/m². This research supports energy conservation in finding the optimum building envelope design by specifying the Window to Wall Ratio (WWR) which will fulfill the OTTV requirement. Five office buildings in Jakarta, eight story and above are used in this study. The result shows that WWR less than or equal to 0.40 will produce OTTV value that suits the SNI 03-6389-2000 requirement. It is also shown that OTTV value is not the only factor that guarantees energy conservation.
Abstract in Bahasa Indonesia :
Sistem tata udara menggunakan 50-70% energi dari keseluruhan energi listrik yang digunakan dalam sebuah bangunan gedung perkantoran. Beban pendinginan dari suatu bangunan gedung terdiri dari beban internal, yaitu beban yang ditimbulkan oleh lampu, penghuni serta peralatan lain yang menimbulkan panas dan beban external yaitu panas yang masuk dalam bangunan diakibatkan oleh radiasi matahari, konduksi dan ventilasi/infiltrasi melalui selubung bangunan. Untuk mengurangi beban external, SNI 03-6389-2000 menentukan kriteria disain yaitu Overall Thermal Transfer Value (OTTV) harus lebih kecil atau sama dengan 45 Watt/m². Untuk mempermudah perencanaan untuk mendukung upaya konservasi energi penelitian ini berusaha mencari Window to Wall Ratio (WWR) yang dapat memenuhi OTTV yang disyaratkan. Studi dilakukan pada lima gedung perkantoran di Jakarta, yang memiliki ketinggian lebih dari delapan lantai. Hasil penelitian ini menunjukkan WWR lebih kecil atau sama dengan 0,40 menghasilkan nilai OTTV memenuhi syarat yang ditentukan oleh SNI 03-6389-2000. Ditunjukkan pula bahwa nilai OTTV bukan satu-satunya batasan yang menjamin gedung hemat energ
STABILISASI TANAH LIAT SANGAT LUNAK DENGAN GARAM DAN PC (PORTLAND CEMENT)
Get PDFAdding sodium chloride, as admixture, and Portland Cement, as stabilizer, to a very soft clay increase its plasticity index (PI), Californian Bearing Ratio (CBR), and Unconfined Compression Strength (UCS). This paper presents the results of testings done to very soft clay from Margomulyo, Surabaya. The results show a promising tendency. Anyhow a wider and comprehensive research is still needed to ensure the long-term effect of the soil stabilization.
Abstract in Bahasa Indonesia :
Penambahan garam (sodium chloride) dan PC (Portland Cement) meningkatkan PI (Plasticity Index), CBR (Californian Bearing Ratio), dan UCS (Unconfined Compression Strength) dari tanah lempung sangat lunak. Dalam makalah ini disajikan hasil pengujian yang dilakukan terhadap lempung sangat lunak dari daerah Margomulyo, Surabaya. Hasilnya menunjukkan kecenderungan yang menggembirakan, namun penelitian yang luas dan komprehensif masih diperlukan untuk peningkatan stabilitas tanah dalam jangka panjang