| 1. |
- al Amli, Ali Sabah, et al.
(författare)
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Behavior of Reinforced Concrete Beams with effect of Stiffened Plates
- 2019
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Ingår i: Civil Engineering Journal. - Iran : Salehan Institute of Higher Education. - 2676-6957 .- 2476-3055. ; 5:12, s. 2569-2578
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Tidskriftsartikel (refereegranskat)abstract
- This study presents experimental work including an investigation conducted on five simply supported reinforced concrete beams under pure torsion. First beam without strengthening as a control beam. The other four beams were strengthened externally by bolted thin steel plates. For this test the load was applied gradually. The torque was increased gradually up to failure of the beam. The variables were the thickness and height of the steel plate that was externally connected to both sides of the rectangular reinforced concrete beam. The test results for the beams discussed are based on torque-twist behavior. The experimental results show that the attachment of thin steel plates by mechanical means to beams provides a considerable improvement in the torsional behavior of the reinforced concrete beams. Comparable to the reference beam, the maximum increase in the cracking and the ultimate torque of the composite beam was recorded for the reinforced concrete beam that strengthen by steel plate of 150 mm height, 2 mm thickness and 50 mm spacing between shear connectors (B1). The results revealed that the cracking torque, ultimate torque, global stiffness of beam and beam ductility for all composite beams increase with the increase of the plate's thickness, plate's height.
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| 2. |
- Al Amli, Ali Sabah, et al.
(författare)
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Study Numerical Simulation of Stress-Strain Behavior of Reinforced Concrete Bar in Soil using Theoretical Models
- 2019
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Ingår i: Civil Engineering Journal. - Iran : C EJ PUBLISHING GROUP. - 2476-3055. ; 11:5, s. 2349-2358
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear analysis for reinforced concrete members (R.C.) with two types of bars also with unsaturated and saturated soils was used to represent the models. To control the corrosion in the steel bar that used in R.C. member and decrease the cost, the geogrid with steel bar reinforcement are taken in this study to determine the effect of load-deflection and stress-strain relationships. The finite element method is used to model the R.C. member, bars and soil. A three-dimensional finite element model by ABAQUS version 6.9 software program is used to predict the load versus deflection and stress versus strain response with soil. The results for the model in this study are compared with the experimental results from other research, and the results are very good. Therefore, it was concluded that the models developed in this study can accurately capture the behavior and predict the load-carrying capacity of such R.C. members with soil and the maximum stresses with strains. The results show plastic strain values in the R.C. member with saturated soil are larger than their values in unsaturated soil about (54%, 58%, and 55% and 52%) when the geogrid ratios are (without geogrid, 60%, 40% and 20%) respectively, with the same values of stresses.
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| 3. |
- Alaneme, George U, et al.
(författare)
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Numerical Analysis and Parametric Study on Multiple Degrees-of-Freedom Frames
- 2023
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Ingår i: Civil Engineering Journal. - : CEJ. - 2676-6957 .- 2476-3055. ; 9:7, s. 1709-1736
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Tidskriftsartikel (refereegranskat)abstract
- The design of multiple degrees-of-freedom frames is critical in civil engineering, as these structures are commonly used in various applications such as buildings, bridges, and industrial structures. In this study, a six-degrees-of-freedom beam-column element stiffness matrix was formulated by superposition of beam and truss elements stiffness matrices and was adapted to statically analyze indeterminate frame structures. The development of a numerical model for the frame structures was achieved using the finite element method in the current study. Also, the investigation of the effects of various parameters such as frame geometries, material properties, and loading conditions was conducted on the internal forces developed in the frame structures. Three different parametric study cases that presented the frame structures with varying geometries and loading conditions were analyzed utilizing this matrix approach for the sake of emphasis and to evaluate the flexibility and adequacy of this formula to analyze the indeterminate frames using the MATLAB software. The analysis method comprised the derivation of the system displacements employing the relationships between the stiffness matrix and fixed end forces as the force vector and taking the attained displacements, which would be transformed to the local coordinates to obtain the member forces. The computed results from the element stiffness matrix approach were further statistically compared with the results achieved from the finite element software (SAP2000) applying the analysis of variance (ANOVA). The statistical results showed a P-value > 0.05, which indicated a good correlation between the compared results and adequate performance for the derived beam-column element matrix formula method.
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| 4. |
- AlOmar, Mohamed Khalid, et al.
(författare)
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Short-, Medium-, and Long-Term Prediction of Carbon Dioxide Emissions using Wavelet-Enhanced Extreme Learning Machine
- 2023
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Ingår i: Civil Engineering Journal. - : Salehan Institute of Higher Education. - 2676-6957 .- 2476-3055. ; 9:4, s. 815-834
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Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide (CO2) is the main greenhouse gas responsible for global warming. Early prediction of CO2 is critical for developing strategies to mitigate the effects of climate change. A sophisticated version of the extreme learning machine (ELM), the wavelet enhanced extreme learning machine (W-EELM), is used to predict CO2 on different time scales (weekly, monthly, and yearly). Data were collected from the Mauna Loa Observatory station in Hawaii, which is ideal for global air sampling. Instead of the traditional method (singular value decomposition), a complete orthogonal decomposition (COD) was used to accurately calculate the weights of the ELM output layers. Another contribution of this study is the removal of noise from the input signal using the wavelet transform technique. The results of the W-EELM model are compared with the results of the classical ELM. Various statistical metrics are used to evaluate the models, and the comparative figures confirm the superiority of the applied models over the ELM model. The proposed W-EELM model proves to be a robust and applicable computer-based technology for modeling CO2concentrations, which contributes to the fundamental knowledge of the environmental engineering perspective.
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| 5. |
- Alzeyadi, Ali, et al.
(författare)
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Study of Biomass Bottom Ash Efficiency as Phosphate Sorbent Material
- 2019
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Ingår i: Civil Engineering Journal. - Iran : C EJ PUBLISHING GROUP. - 2476-3055. ; 11:5, s. 2392-2401
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Tidskriftsartikel (refereegranskat)abstract
- Excessive richness of nutrients in water bodies such as rivers, lakes and ponds lead into deterioration of aquatic life as a results of dense growth of algae. Phosphate is one of the main nutrients that should be controlled to prevent this serious issue. Utilizing low cost material as a phosphate sorbent is offering a treatment method characterized as a sustainable solution. In this study the efficiency of biomass bottom ash BBA as phosphate sorbent material from aqueous solution is investigated. Batch experiments were undertaken, in which a particular mass of BBA was brought into contact with the phosphate solution. The experiments studied the influence of pH (different phosphate solutions were prepared with pH range 4 to 8), temperature (adsorption capacity measured at the temperature range of 10 to 30 °C), and contact time. In addition, the adsorption isotherm models were also applied to better understand the mechanism of phosphate sorption by BBA. The results revealed that the bonding between the cations (BBA surface) and anions (phosphate solution) is significantly affected by the pH of the solution. BBA presents an excellent phosphate sorption, especially, at low pH value and temperature around 20 oC. The method of this research can be adopted as a followed strategy for examination the capability of selected material for phosphorus removal from wastewater.
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| 6. |
- Bahrami, Alireza, et al.
(författare)
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Important Criteria for Swedish Construction Companies to Choose Environmentally Friendly Concrete
- 2023
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Ingår i: Civil Engineering Journal. - : CEJ. - 2676-6957 .- 2476-3055. ; 9:1, s. 197-207
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Tidskriftsartikel (refereegranskat)abstract
- Today, ordinary Portland cement-based concrete is one of the most important building materials and is widely used in new building construction, which is an environmental problem, as cement production accounts for 5%-8% of the world's carbon dioxide emissions. Thus, the need for using more environmentally friendly concrete (EFC) is growing. However, it is stated that Swedish construction companies are reluctant to change and adopt new construction methods and materials. This research aims to map the important criteria for Swedish construction companies to choose EFC for use in their projects. The study is carried out based on a literature study and a questionnaire survey. The questionnaire is designed considering the significant criteria of EFC derived from the literature study. The respondents from the Swedish construction companies were asked to rate these various criteria. The collected results are presented with bar graphs. The results show that the highest valued criterion by the respondents for the use of EFC in the projects is its long-term properties, while the lowest one is the possibility of introducing a specific ceiling for greenhouse gas emissions by the companies.
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| 7. |
- Eriksson, Per Erik, et al.
(författare)
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Procurement of Railway Infrastructure Projects : A European Benchmarking Study
- 2017
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Ingår i: Civil Engineering Journal. - : C EJ PUBLISHING GROUP. - 2476-3055. ; 3:4, s. 199-213
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Tidskriftsartikel (refereegranskat)abstract
- This benchmarking study compares how railway investments are procured in five European countries: Sweden, Norway, Germany, the Netherlands, and the UK. In total, 19 procurement managers and project managers were interviewed. This study compares the national rail clients' procurement strategies regarding: delivery system, reward system, contractor selection, and collaboration model. Historically, these clients have used in-house production. The first step towards a gradually increased usage of the market was to outsource the construction activities while keeping the design and development competence in-house. All five countries have mainly used Design-Bid-Build contracts in their initial outsourcing. However, the last few years there is a discernible trend in Sweden, Norway, the Netherlands and the UK towards allocating more design and development responsibilities to contractors (i.e. Design-Build contracts) and increasing the strategic focus on cooperation. The UK and the Netherlands are forerunners in this trend that can be viewed as a third step in the transition towards a market oriented railway sector. Norway and Sweden is in the middle of this transition, whereas Germany has not initiated this change. The transition towards a gradually increased usage of the market has two main dimensions; degree of cooperation and degree of contractor freedom, which differs among the countries. The UK and Sweden focus on increasing both these dimensions, while The Netherlands and Norway mostly focus on increasing the degree of contractor freedom. Germany still limits both dimensions by performing design and development in-house and letting contractors compete for construction work in Design-Bid-Build contracts. Due to historical and cultural reasons, Deutsche Bahn in Germany is very hesitant to engage in collaboration with external suppliers; focusing on competition is considered more appropriate and less controversial.
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| 8. |
- Mohamed, Mahmood J., et al.
(författare)
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Modelling Flood Wave Propagation as a Result of Dam Piping Failure Using 2D-HEC-RAS
- 2023
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Ingår i: Civil Engineering Journal (Iran). - : Salehan Institute of Higher Education. - 2676-6957 .- 2476-3055. ; 9:10, s. 2503-2515
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, there has been a serious request for innovative, accurate approaches to be determined and controlled for dam failures. The present study aims to explore and evaluate the flood wave parameters that result from a dam break due to piping failure occurring in the body of the dam and routing the flood waves. Mosul Dam, which lies in the north of Iraq, and a reach of the Tigris River downstream the dam to Samarra Barrage at about 470 km are selected as a case study. A two-dimensional Hydrologic Engineering Center River Analysis System (2D HEC-RAS) and the Geographic Information System (GIS) have been supposed to be suitable for development calculations of the flood wave parameters based on the Digital Elevation Model (DEM) and land cover satellite images that enhance the calculations. The reservoir and two-dimensional flow area are delineated and incorporated with DEM. Manning`s coefficient for the whole area has been extracted according to the Land Cover satellite image, which showed that its value ranges between 0.025 to 0.037 with a correlation coefficient R2 equal to 0.845 and 0.801 for the calibration and validation processes, respectively. The results of the scenario display a substantial performance of the maps produced from the model that represented the depth, velocity, and water surface elevation. All the maximum values of dam break parameters lie near the dam body and slightly decrease downstream. It is pre-eminent that the 2D HEC-RAS model is appropriate for analyzing and simulating the occurrence of dam breaches by visualizing the distribution of flood wave depth and velocities in two dimensions. Hence, the clear improvement in producing maps, which monitor the spread of hydrodynamic waves, gives an indication of risk areas that are threatened by inundation and aids in the formulation of emergency plans.
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| 9. |
- Murugan, Prakash, et al.
(författare)
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Experimental Study on Hollow Steel Sections Under Elevated Temperature
- 2024
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Ingår i: Civil Engineering Journal. - : CEJ Publishing Group. - 2676-6957 .- 2476-3055. ; 10:3, s. 859-884
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Tidskriftsartikel (refereegranskat)abstract
- Structures known as modular buildings are made in factories and then moved to construction sites, where they are assembled. The efficacy of modular structures under many uncertainties has to be thoroughly investigated as demand rises; fire is one such uncertainty. The purpose of this study is to ascertain how high temperature affects the components of modular constructions. In the current study, hollow steel columns and beams were taken into account as components of a modular construction. Using ABAQUS, several situations were examined depending on the span length to determine the important locations of the members. Experimental research was conducted on the critical regions identified by the analysis, and the results were contrasted with those of the analysis. A high-temperature localized heating furnace was used for the experimental testing. The findings demonstrated that for spans of 250 mm and 500 mm, the central area of the beams was essential, and the load-carrying capacity was six times less than that of heating at the extremities of the beams. Similar to the beams, columns exhibited less fluctuation than the beams and were weaker in the bottom area when exposed to high temperature. When compared to other places, the capacity was reduced by 1.1 times, and in Case 1, the capacity reduction with regard to loading was 1.68 times greater.
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| 10. |
- Murugan, Vishal, et al.
(författare)
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Mechanical and Postfire Structural Performances of Concrete under Elevated Temperatures
- 2023
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Ingår i: Civil Engineering Journal. - : CEJ. - 2676-6957 .- 2476-3055. ; 9:8, s. 1863-1879
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates the mechanical and postfire structural performances of concrete under elevated temperatures (200°C, 400°C, 600°C, and 800°C) after 7 and 28 days of concrete curing. The main objective of this study is to evaluate the post-fire behavior of concrete structures and how their modulus of elasticity values influence their structural parameters. Mechanical studies, namely, the compressive strength, splitting tensile strength, and flexural strength, were performed on cubes, cylinders, and prism beams under normal and elevated temperatures. Non-destructive tests, like rebound hammer and ultrasonic pulse velocity, were also conducted on concrete cubes to obtain the strength of concrete before and after heating the specimens. Microstructural studies, in particular, scanning electron microscope and energy dispersive x-ray spectroscopy, were done to analyze the changes in the chemical composition of concrete under the effect of the temperatures. The weight loss of the concrete specimens was assessed under the elevated temperatures. The results indicated that the geometric shapes of the specimens influenced the loss in the moisture content of concrete under an elevated temperature scenario. Microstructural studies revealed the changes in the chemical composition under the elevated temperatures. The results of this research can be further integrated for industrial applications.
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