Civil Engineering Dimension (E-Journal)
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Benchmarking the Performance of Construction Procurement Methods against Selection Criteria in Nigeria
Get PDFThe study developed performance indices by the widely used procurement options in Nigeria on selection criteria. The traditional mean and standardized ratio were used to form the utility coefficients. Results revealed that performance by the procurement options depended on the respondents’ categorization and cost categorization of projects. Public clients ranked the lump sum contracts more able to achieve speed for projects up to N100 million (Naira) while the private clients believe it is the design-build. As regards quality, public clients rated the Build-Own-Operate-Transfer (BOOT) system as most able to achieve the quality criterion whereas private clients rated design-build for projects up to N100 million (Naira). The study then concluded that, in the Nigerian construction industry participants do not agree on the performance of the procurement options on selection criteria
Behavior of Expansive Clay of Ngawi Region (East Java) Under Water Content Variation
Get PDFWhen expansive clay is wetted, deformations occur both vertically and laterally. If it is tested in an oedometer ring apparatus the lateral deformation will be restrained by the wall of the ring. This paper present the results of an experimental investigation using modified oedometer test for measuring the vertical and lateral swelling potential and lateral pressure of disturbed expansive clay soil. Series of modified oedometer tests were conducted with initial water content of 20%, 25% and 30%, to predict the vertical and lateral swelling potential and lateral swell pressure. The results of the test show that the percentages of the vertical swell is bigger than the lateral swell. Both vertical and lateral swell, linearly decrease with increasing initial water content. The lateral swell pressure also decreases with increasing initial water content
Predicting Nonlinear Behavior and Stress-Strain Relationship of Rectangular Confined Reinforced Concrete Columns with ANSYS
Get PDFThis paper presents a nonlinear finite element modeling and analysis of rectangular normal-strength reinforced concrete columns confined with transverse steel under axial compressive loading. In this study, the columns were modeled as discrete elements using ANSYS nonlinear finite element software. Concrete was modeled with 8-noded SOLID65 elements that can translate either in the x-, y-, or z-axis directions from ANSYS element library. Longitudinal and transverse steels were modeled as discrete elements using 3D-LINK8 bar elements available in the ANSYS element library. The nonlinear constitutive law of each material was also implemented in the model. The results indicate that the stress-strain relationships obtained from the analytical model using ANSYS are in good agreement with the experimental data. This has been confirmed with the insignificant difference between the analytical and experimental, i.e. 5.65 and 2.80 percent for the peak stress and the strain at the peak stress, respectively. The comparison shows that the ANSYS nonlinear finite element program is capable of modeling and predicting the actual nonlinear behavior of confined concrete column under axial loading. The actual stress-strain relationship, the strength gain and ductility improvement have also been confirmed to be satisfactorily
An Investigation of the Performance of Due Process Mechanism in the Execution of Construction Projects in Nigeria
Get PDFVarious procurement methods are in use in the award of public contract in Nigeria. The traditional method, which is widely used, has been criticized for its non-performance in projects execution and delivery. To avoid the adverse effects of the current contract procurement methods, Due Process mechanism was introduced. This study, therefore investigated the level of importance of due process by parties involved in the award of public contracts, the performance of Due Process and factors that may affect its functions. The survey was carried out by administering structured questionnaires and interviews on the practitioners in the construction industry that were in the private and public sectors. The data collected were analysed with the use of both descriptive and inferential statistics. The study showed that Due Process has become a new initiative being widely embraced by parties in public contract and has helped in saving public fund by corrupt practices that usually characterize award of contracts. The study also showed that the absence of legal and other institutional frameworks were among the factors that affect the performance of due process in the country
Kriging-Based Finite Element Method: Element-By-Element Kriging Interpolation
Get PDFAn enhancement of the finite element method with Kriging shape functions (K-FEM) was recently proposed. In this method, the field variables of a boundary value problem are approximated using ‘element-by-element’ piecewise Kriging interpolation (el-KI). For each element, the interpolation function is constructed from a set of nodes within a prescribed domain of influence comprising the element and its several layers of neighbouring elements. This paper presents a numerical study on the accuracy and convergence of the el-KI in function fitting problems. Several examples of functions in two-dimensional space are employed in this study. The results show that very accurate function fittings and excellent convergence can be attained by the el-KI
Effects of Confinement on Interaction Diagrams of Square Reinforced Concrete Columns
Get PDFTo prevent brittle failure, the design of a structural column in a seismic-resistant building is of important consideration, particularly in terms of confinement. In the recent building code, the need of closely-spaced stirrups in a structural member, such as column becomes compulsory due to the ductility and strength considerations. However, the design is based on the simplified block stress of unconfined concrete, and does not account for the strength gain due to the presence of confinement. To investigate the effects of lateral confinement on the column capacity, an analytical study is carried out. Both the strength gain in concrete core and the loss of strength in the cover are considered in the analytical models to exhibit the remaining strength gain after the mobilization of strength gain in the core concrete to compensate the loss of strength in the concrete cover. There are six key parameters primarily influence the effectiveness of lateral confinement. The most influencing parameter is found to be the spacing of transverse steel. The presence of closely-spaced lateral confinement significantly increases the magnitude of stress-strain curve of concrete. This increase expands the interaction diagram of the column particularly when it is in the compression-controlled region (for lower-story columns when axial load dominates the behavior)
Flood Mitigation of Nyando River Using Duflow Modelling
Get PDFDuflow surface water hydrodynamic model has been applied using a case study from Nyando catchment in the western part of Kenya in Africa to simulate various extreme flood behaviours and their retardation levels by using selected structural measures as flood mitigation techniques. The objective of this case study was to establish a design flood recommendable for mitigation, and to identify the most cost effective flood mitigation structure. Various design flows are simulated against the different proposed structures hence, the optimal structure can be recommended when economical, social and environmental constraints are considered in the decision making process. The proposed four flood mitigation structures flood plain extension, embankment (dykes), channel by-pass, and green-storage were simulated for 20-year recurrence interval flood to determine their individual responses in storing excess water. The result shows that building a green-storage is the best and optimal structure for flood mitigation
The Tension Strength Experiment of Thread Connection Based on The Depth of Thread Penetration
Get PDFThread connection has been used for a long time. Presently, this kind of connection is the main connection in steel construction. This research aims to comprehend further the mechanism of the thread connection with respect to the depth of thread penetration. Tensile strength of thread connection was derived experimentally using two steel rods. The diameter of the first steel rod was ¾ inch (18.5 mm) and threaded on one end by 16 threads per inch. The diameter of the second steel rod was 45 mm and functioned as nut. From the results of the experiment, it can be concluded that rod failure will happen if the depth of thread penetration is equal to or bigger than 90% of nut minor diameter. Meanwhile, thread failure will happen if the depth of thread penetration is less than 90% of nut minor diameter. It is also shown that the correlation between the number of thread and the maximum load which can be supported by the connection is not linear
Evaluation of The Impacts of VMS on Traffic Performance Measures in An Urban Area in Indonesia
Get PDFVariable Message Sign (VMS) is especially recommended for congested flow conditions. The aim of this study is to investigate how drivers in a large city in a developing country with many specific geometric and traffic conditions and also specific driver behaviour, use VMS in aid of choosing route for their inter-city trips. Furthermore, to explore the impact of the use of the information on increasing traffic performance measures. A case study was carried out in Bandung, Indonesia. Microscopic traffic simulations were used in this study to evaluate traffic performance measures. The results of the evaluation found that VMS has insignificant impact on drivers’ route choice behaviour. The results indicated that drivers in Bandung rely much on their experience of traffic conditions commonly occur in the city and demonstrated that VMS has no significant impact to increase traffic performance, but has better impact on the roads with higher number of alternative roads
The Development of An Analytical Overlay Design Procedure
Get PDFPavement structural evaluation using pavement modulus values resulting from back calculation process on non-destructive deflection data has been adopted to quantify objectively the conditions of existing pavements under various traffic loading and environmental conditions. However, such an advanced technique is not yet followed widely by advances in analytical overlay design procedures. One possible reason is perhaps due to its requirement to perform complex computations. A new module of computer program BackCalc has been developed to do that task based on the allowable maximum deflection criterion specified by the Asphalt Institute’83. The rationale is that adequate overlay thickness will be computed by iteration to result in theoretical maximum deflection that closely matches against the specified allowable maximum deflection. This paper outlines the major components of the program module illustrated by using a practical example. The overlay thickness obtained was found to be comparable with that of the known AASHTO’93 metho