- Détails du magazine
- Première publication
- 23 May 1993
- Période de publication
- 4 fois par an
- Accès libre
Analysis of Static and Cyclic Traffic Loading of an Embankment Supported by a Geogrid Retaining Structure
Pages: 1 - 8
The article deals with a deformation analysis of a road embankment under different types of static and cyclic loading. A typical cross-section of a road embankment supported by geogrid retaining structures is considered. In the case of a design, the load is usually applied as a distributed static load. The analysis presented in the paper includes all the most loading methods used. Because there are only a few measurements for these types of construction in a given region, the analysis also includes a cyclic loading that aims to simulate real traffic loading. The cyclic loading considered the weights of cars and trucks and the distances between them, based on traffic intensity measurements. The study results showed how significant the differences in vertical and horizontal deformations of an embankment are when the different types and methods of static loading are used in a design. The results of the cyclic loading showed the deformations that can be expected from current real traffic.
- Traffic loading
- Static loading
- Cyclic loading
- Road embankment
- Geogrid retaining structure
- Accès libre
Sizing of an Autonomous Individual Solar Water Heater Based in Oran, Algeria
Pages: 9 - 16
The study concerns an autonomous individual solar water heater installed in the Oran region in Algeria. Supplied by two sources of solar thermal and photovoltaic energy, this solar water heater provides domestic hot water for the needs of an average family of 6 people. A comparative approach was made to find the most adequate solution between increasing the surface area of the thermal solar panel or those of the photovoltaic panels, by analyzing the solar fraction and the efficiency of the thermal panels. The choice was make for a thermal panel with a surface area of 4 m2 and complete with 16 photovoltaic panels, thus resulting in a total surface area of 14 m2 to obtain an autonomous solar water heater powered only by solar energy. Another option was considered by incorporating a photovoltaic thermal panel, and substantial savings were found.
- Solar water heater
- Accès libre
Estimation of the Uplift Resistance for an Under-Reamed Pile in Dry Sand Using Machine Learning
Pages: 17 - 26
Under-reamed piles are extensively used to resist uplift forces and settlements. The objective of the present study is to develop various machine learning models (linear and non-linear) and determine the best model to estimate the ultimate uplift resistance of under-reamed piles embedded in cohesionless soil. The machine learning models were developed considering the following input parameters: the density index, dry density, base diameter, angle of an enlarged base with a vertical axis, shaft diameter, and embedment ratio. A linear equation is proposed to estimate the ultimate uplift resistance based on Multivariate Linear Regression analysis with a mean absolute error equaling 0.25kN and 0.50kN for loose and dense sands respectively. The Decision Tree Regression model provides an excellent degree of accuracy with a mean absolute error of 0.02kN and 0.02kN in cases of loose and dense sands respectively.
- Uplift resistance
- Machine learning
- Multivariate linear regression and decision tree regression
- Accès libre
Regulation of Telescopic Water Intake Operations
Pages: 27 - 32
Telescopic water intake structures play an important role in a water management system. The article is devoted to the improvement of telescopic water intake structures and the development of a solution for regulating their operation. Different types of water intakes are analyzed, and their shortcomings are identified. The structures of known telescopic water intakes are reviewed, and their operating principles are analyzed. It has been determined that the design of existing telescopic water intake structures lacks a device for stopping the operation of the intake of water. A structural solution for stopping and regulating the operation of a telescopic water intake is proposed. The construction of an additional ballast pontoon to be welded to the first section of the telescopic pipeline is proposed in order to regulate and stop the operation of the water intake. A methodology for calculating and designing an additional ballast pontoon for a telescopic water intake has been developed, and a specific example for its implementation has been provided. Based on the results of the research, the main parameters of the additional ballast pontoon structure have been established, and the methodology for its calculations has been developed.
- Ballast pontoon
- Telescopic water intake
- Accès libre
Feasibility of Using Energy Performance Contracting for the Retrofit of Apartment Buildings in Slovakia
Pages: 33 - 42
This study is focused on the feasibility of using energy performance contracting (EPC) for the retrofit of two apartment buildings constructed using precast concrete technologies in Slovakia decades ago. The retrofit packages were defined, and their suitability for EPC was evaluated through discounted payback. The uncertainties in the profitability calculations were covered by designing five possible economic developments and defining input ranges instead of just single inputs. The measures in the technical systems were shown to be more feasible than the retrofit of the building envelopes. The potential to finance the selected measures for technical systems through EPC was further evaluated. It was shown that, for at least one of the two buildings studied, the EPC was recommended only for the economic developments with a notable increase in energy prices compared to the baseline that referred to the situation before the Covid-19 pandemic. In the best case, the payback was four years for one building and seven years for the other; thus, both were potentially suitable for EPC. However, for a complex retrofit, the EPC must be combined with a different funding source to also finance other retrofit measures.
- Energy performance contracting (EPC)
- Building retrofit
- Accès libre
The Impact of Car Transport on the Environment and Public Spaces in Cities: Case Study from Slovakia
Pages: 43 - 52
The increasing traffic volume of individual car transport results in environmental damage and new space requirements for parking. Parked cars occupy public space that a municipality could use for non-transport purposes. An effective urban parking policy is a solution that could influence transport and significantly improve the quality of public spaces and the environmental burden of traffic. Effective parking management can increase revenues to a city budget to be used for further urban development. The regulation of parking and charging are unpopular topics for politicians. They are afraid of the adverse reactions of local inhabitants and fear that they will not be re-elected. However, experience has shown that if the process and implementation of regulated parking are well managed, citizens will appreciate its benefits. People will begin to value public space more and transform it into space for all residents and not just car owners. The goal of this paper is to present research in which people were asked what they would motivate them to use a different mode of transport instead of a car. The most common answer was more public transport connections and cheaper traveling or traveling free of charge.
- Car ownership
- Parking policy
- Accès libre
Workability and Strength Characteristics of Alkali-Activated Fly ASH/GGBS Concrete Activated with Neutral Grade Na2SiO3 for Various Binder Contents and the Ratio of the Liquid/Binder
Pages: 53 - 64
Alkali-activated fly ash/GGBS concrete (AAFGC) is a new blended concrete that has been studied by many researchers due to its environmental advantages and better technological characteristics. However, the effect of various factors on AAFGC fresh and hardened properties has not yet been thoroughly studied. The literature mainly describes the combination of NaOH and Na2SiO3 as an activator for the AAFGC’s activation, but alkali-activated GGBS concrete (AAGC) prepared with this activator solution is less workable due to its rapid setting behaviour. In this study, AAFGC was prepared using neutral grade liquid Na2SiO3 with a SiO2/Na2O ratio of 2.92. An experimental program was performed for fly ash-GGBS combinations (100-0, 50-50, 0-100), solution/binder ratios (0.6, 0.65, 0.7) and binder contents (300, 400 and 500 kg/m3) to evaluate the workability and the compressive and tensile strength of AAFGC. The results of this study show that a water glass of 2.92 silica modulus used as an activator to prepare AAFGC under ambient curing is very useful in the construction industry.
- Alkali-activated fly ash/GGBS concrete
- Neutral grade liquid NaSiO
- Initial and final setting time
- Tensile strength