Tom 17 (2022): Zeszyt 1 (December 2022)

The presented study deals with the space located in the attic of an older building after reconstruction. Originally, the attic space was not used, as it did not have sufficient headroom. The reconstruction was designed in such a way that the entire original pitched roof was gradually raised by 1.2 meters in parts, creating a full-fledged space under the pitched pitched roof. The visual connection of the interior space with the exterior was ensured by continuous strips of vertical windows around the perimeter of the building, each window measuring 600x600 mm. The space is also illuminated by several skylights at roof level, which, although they ensure sufficient penetration of daylight from above into the interior, at the same time allow for considerably unpleasant overheating. The task was to find a way to optimize the size of transparent surfaces and determine the accumulation of building structures in order to achieve an acceptable cumulative effect of daylight and overheating, i.e., permissible increase in indoor air temperature in summer. It means trying to theoretically design a suitable and comfortable interior space in the attic in an already existing building.

The mechanical properties of mortar containing Polyethylene Terephthalate (PET) as Strapping Band Fibers (SBF) replacing natural sand have been studied by many researchers. These studies indicate that when SBF is used as a substitute for sand in mortar, the characteristics in both the fresh and hardened states are altered. This experiment’s purpose is to valorize local materials, which are abundant in the region of Djelfa (Algeria), in cement mortar manufacturing and to discuss the influence of these materials on the mechanical and physical characteristics of the resulting mortar at the room, and at the high temperature. This study presents the results of an experimental investigation into the effects of high temperatures on the properties of dune sand mortar made with strapping band fibers. The method for formulating the mortar mixes was based on the progressive replacement of dune sand by PET fibers, with weight contents of 0%, 0.5%, 1%, 1.5%, 2%, and 2.5%. Several tests have been carried out to study the evolution of the different characteristics of mortar mixtures. The workability, bulk density, compressive and tensile strengths, and all samples were subjected to temperatures of ambient, 100 °C, 200 °C, and 400 °C. The results demonstrate that the inclusion of the recycled fibers and the preservation mode had remarkable effects on the characteristics of the mortar obtained.

Water losses due to leakage are a pernicious problem for water utilities. Understanding and quantifying Non-Revenue Water (NRW) and water loss components is the first step in the management of urban water losses. Hydraulic modeling is a powerful tool to predict the impacts of different management scenarios on the hydraulics of the Water Distribution Network (WDN). The water distribution network (WDN) can be divided into a number of District Meter Areas (DMAs) with suitable sizes in order to apply pressure management. In this study, the Fixed Area Variable Area Discharge (FAVAD) concept and the number of leaks were analyzed for a number of water network pressure management areas in the city of Bendjerrah – the district of Guelma, Algeria. The analysis identified some anomalies concerning the parameters of some networks; especially those related to leakage exponent N1 values greater than 1.5. The approach used in this framework is based on the estimation of the leakage from the Minimum Night Flow (MNF) and the burst frequency of Average Zonal Pressure (AZP). After the use of this approach and the calibration procedure using the Epanet-calibrator on real District Meter Areas, the obtained results are very close to the real state of the network. In addition, this paper studies the possibility of explicitly incorporating the variation of the leakage zone in the hydraulic modeling of the water distribution systems. The results show that the power equation leakage exponent N1 estimates the total system leakage with an error of up to 20%. From the Minimum Night Flow, obtained by using the South African Night Flow (SANFLOW) practical tool, it was found that the actual losses calculated for sectors 1, 2, and 3 are respectively 25%, 45%, and 30%.

The current use of buildings is facing an unprecedented increase in energy costs, especially in the European Union. The energy costs can be reduced by energy savings and by increased use of renewable energy represented mostly by energy converted from solar radiation. When solar energy is considered to be utilized in buildings, the mismatch between energy availability and energy demand must be solved by energy storage. This paper describes the principles of the use of latent heat thermal energy storage and the possibility of using bio-based phase change materials as heat storage media. Because the latent heat storage media undergo a change of phase during the charging and discharging, proper encapsulation is necessary. The paper presents the main findings of a study focused on the compatibility between coconut oil and selected plastics as materials of encapsulation. The compatibility of selected plastics and Coconut oil was evaluated by laboratory experiment based on the immersion of plastic samples in coconut oil and calculation of change in weight of samples within 17 weeks lasting test. The negligible weight changes were occurred for polycarbonate and polyethylene terephthalate which proves excellent compatibility with Coconut oil.

The objective of this study is to evaluate the effect of pozzolan on the durability of high-performance fiber concretes in two aggressive environments. For this, prismatic test pieces were made at (0%, 10%, 20%, and 40%) of pozzolan and immersed in two acids, hydrochloric and sulfuric. Then characterizations were carried out, such as the loss of mass, the depth of degradation and the mechanical resistance. The results obtained show that with the substitution rate of pozzolan, the loss of mass and the depth of degradation increase in the two acids, while the mechanical strength increases in hydrochloric acid and decreases in sulfuric acid.

Comparative research on the influence of daylight and visual environment on melatonin oscillations and the performance of space users was realized in two identical rooms with different glazing at the Faculty of Civil Engineering of the Slovak Technical University in Bratislava. The glazing in the windows had significantly different transmittances of melanopic light. This article presents measured changes in the intensity of photopic and melanopic daylighting values inside the rooms on horizontal and differently oriented vertical plane. Photopic and melanopic illuminances were measured under cloudy and partly clear skies during several months in 2021 and 2022. The article is also partially devoted to the effect of light from a computer monitor on the spectral composition of light on the eye of a person working with a computer. The article also analyzes the problems associated with the evaluation of non-visual aspects of daylighting of the interior spaces of buildings.

This work investigates the behavior of a silty clay stabilized with 3, 6, 9, and 12 % of ground granulated blast-furnace slag (GGBS), respectively, and 1 % of quicklime used as an activator. The influence of the composite (Quicklime - GGBS) on the immediate behavior of the silty clay is studied by examining the Atterberg limits, the maximum dry density, the optimum moisture content, and the immediate bearing index. The evolution, at different curing periods (1, 7, and 28 days), of the mechanical characteristics of the treated soil, namely unconfined compressive strength, cohesion, and internal angle of friction is also studied. The increase, up to a dosage of 9%, of the GGBS content, leads to an increase in the optimum moisture content, the immediate bearing index, the unconfined compressive strength, and shear strength parameters. Paradoxically, a decrease in the plasticity index and the maximum dry density was observed.

This paper aims to present a deflection prediction model of Near Surface Mounted (NSM) Reinforce Concrete (RC) beams using the Fuzzy Logic Expert System (FLES) with different types of membership functions (MF). The absence of a complete theoretical deflection prediction model of NSM-strengthened RC beams persuades this research to develop an Artificial Intelligence (AI) based prediction model using FLES. The proposed model uses triangular and trapezoidal MF to predict the deflection behavior of six NSM-strengthened RC beams. The research variables are strengthening materials and NSM bar length. In this study, two inputs (applied load and variable length) were used to predict two outputs (deflection of two types of strengthened RC beams). The relative error of predicted values was within 5% and the suitability of fit was close to 1.0 which affirms the efficacy of the FLES. Besides, a tiny difference was detected using triangular and trapezoidal MF for the prediction model.

The estimation of deformations after a large number of cycles is a major concern of geotechnical engineers. This paper presents an explicit formulation of the accumulated cyclic volumetric strain. This study is concerned with cyclic triaxial tests simulated through the calculation by the Finite Element Method. The parameters of identification of the first cycle (loading-unloading) are determined step by step, using, as a soil behavior model, the Soft Soil Hardening Model, then, the behavior of the soil after N cycles (N ---gt--- 1000) is simulated through the formulation proposed as a pseudo-creep. The comparison of the proposed method with several cyclic triaxial tests and a shallow foundation under cyclic loading approves the good compatibility of the proposed formula for this type of problem. This study does not take into account the effect of the grain size and the void ratio, things that can be translated by the coefficients C1 and C2.

The high temperature in the concrete destroys the hydrates of the cement paste. This destruction means the weakness of the materials caused by the deterioration of their mechanical properties.

This work aims to study the behavior of high-performance fiber concrete sets at high temperatures; specifically, we used polypropylene fibers and studied their influence on deterioration behavior.

This study includes high performance concrete and three types of fiber concrete, each containing a specific ratio of polypropylene fibers (0.12 %, 0.18 %, and 0.24 %). Consequently, cubic test specimens (15 cm x 15 cm x 15 cm) were subjected to the temperature of 250 °C, with a speed of 2 °C/min followed by a step of one hour at the target temperature then cooling to the ambient temperature.

The results showed that fiber-reinforced concrete exhibited a better performance when exposed to the temperature studied. The mechanical properties were improved by up to 56% for compressive strength and 86% for tensile strength.

This paper presents a dynamic analytical study to assess the effect of dam height as well as fluid compressibility on the gravity response of a concrete dam, considering the effects of hydrodynamic interaction. The analysis is carried out using the ADINA Finite Element software for empty and full reservoir conditions by considering several models. In the first model, the mass of fluid is taken into account by the concept of Westergaard added mass, in the second model; an acoustic fluid element is used to simulate the effect of water on the reservoir. The height of the dam is one of the main factors affecting the seismic response of gravity dams; because the change in height provides different responses depending on the natural periods, displacements and stresses obtained from static and dynamic analyses. The numerical results showed that the effect of interaction between the dam and the reservoir plays an important role in the precise estimation of the dynamic response of gravity dams. The hydrodynamic water pressure from the reservoir increases stresses in the dam body and horizontal displacements at the crest. The seismic response obtained by the incompressible water model (Westergaard) is compared with that of the compressible water model.

The aim of this research is to assess the mechanical performance of self-compacting concrete containing different percentages of fine aggregates, produced from the wastes generated by the cement plant industry and construction sites. Eight mixes, incorporating cement kiln dust (CKD) and hardened cement waste with partial fine aggregate replacement of 5%, 10%, 15%, and 20%, were produced and compared with a control mix made with 100% of crushed sand. The workability properties (e.g., flowability, passing ability, and resistance to segregation) and mechanical properties (e.g., compressive, flexural, and splitting tensile strengths) of all mixes were evaluated. The results showed that concretes containing recycled fine aggregates proved to have the best mechanical properties, compared to one made with crushed calcareous sand. However, self-compacting concrete with high mechanical strength could be produced with up to 15% wt. CKD replacement and with 10% wt. hardened cement waste replacement.

The characteristics of aerodynamic forces acting on an elliptic cylinder with an aspect ratio of 0.5 with a wind attack angle from 0 to 90° and subjected to the boundary layer wind tunnel were investigated. The model was initially calibrated and compared with the existing work. The aspect ratio of the investigated model was 0.5, and the model was emerging in a turbulent flow. The mean and fluctuating drag and lift coefficients were investigated. The minimum drag coefficient occurred in the wind direction of 0° and the maximum at 90°. The lift coefficient was the largest in the 30° wind direction and the smallest at 0°. Fluctuating coefficients were similar profiles as the mean coefficients. Around the 30° wind direction, an inappropriate phenomenon occurred, caused by the generation of asymmetrical vortices structures and wake instabilities.

The use of superplasticizers in concrete production has become a common practice, especially when a high fluidity is required. On the other hand, the risk of segregation and the stability of these mixtures is ensured by the incorporation of a large volume of fine mineral additions. The present investigation is devoted to the study of the influence of three types of superplasticizers of different chemical compositions, namely: Combined Synthetic Polymers (CSP), Poly-Carboxylate Ether (PCE), and Modified Poly-Carboxylate Ether (MPCE) on the rheological behavior of self-compacting concrete (SCC) as well as on the mechanical properties at 3, 7, and 28 days of curing. Natural pozzolana (NP) and ground granulated blast furnace slag (GGBFS) were used as additions to stabilize the mixtures. The results revealed that the ether-based superplasticizer PCE gave the best workability and mechanical performance with low amounts (high efficiency). In addition, blast furnace slag promotes the obtaining of better properties whether in the fresh or hardened state compared to natural pozzolana.

This article emphasizes the value of applying sophisticated constitutive soil models in numerical modeling as daily geotechnical practice. The capabilities of two different constitutive relations for the modeling of the second Heinenoord bored tunnel are compared. The hypoplastic model of Wolffersdorff for granular materials (Hypo) is a relatively simple model without recourse to yield surface or plastic potential based on rational mechanics, whereas the chosen elastoplastic model, the Hardening Soil Model (HSM) belongs to the non-associative plasticity with double hardening. A modification of the hypoplastic model with improved intergranular strain (IGS) was tested, leading to improve model behavior. Comparisons between numerical simulations and experimental values demonstrate the advantages of using the hypoplastic model with improved intergranular strain (IGS).

The paper presents a theoretical analysis that models the effects of temperature load induced on a two-pole, twobox reinforced concrete bridge. Implemented was theoretical analysis of thermodynamic effects, which was performed on a closed double-box reinforced concrete bridge structure. The modelling and analysis only considered the upper part of the load-bearing bridge structure. This type of bridge was selected to present the results of this study which analysed the worst effects of temperature acting on the bridge structure.

The stone column is a cost-effective, sustainable, and technically sound ground improvement solution for enhancing bearing capacity, minimizing settlement, and mitigating the liquefaction potential of a wide range of soils. In this study, the main methods of stone column execution are briefly explained, design approaches are discussed, and testing procedures are elaborated on in more detail. The results of plate load tests (PLT) are numerically simulated to back-calculate stone column properties. In this research, the Hardening Soil model (HS) is selected to simulate stone columns and soil profiles. The outcomes of this modelling and the adopted calculation approach are verified by three-zone load tests (ZLT) performed on grounds reinforced by stone columns in various projects. Reasonably good matches are observed between experimental and numerical results, approving parameters back-analyzed from PLTs and the employed calculation methodology. Finally, a widely used analytical approach of the calculation of stone columns (Priebe method) is compared with the numerical and experimental results of the studied ZLTs. The comparison confirmed that the Priebe method could practically calculate the settlement of grounds treated by stone columns although settlements were slightly higher than experimentally observed values. In the end, the advantages and limitations of each method are discussed.

The mechanical parameters of the soil that must be introduced into geotechnical calculations, in particular those carried out by the Finite Element Method, are often poorly understood. The search for the numerical values of these parameters so that the models best reflect the observed reality constitutes the inverse analysis approach. In this article, we are interested in the identification of the mechanical parameters of the soil based on the principle of inverse analysis using the two methods of stochastic optimization, the genetic algorithm and the hybrid genetic algorithm with Tabu search. Soil behavior is represented by the constitutive soil Mohr-Coulomb model. The identification relates to the following two parameters: The shear modulus (G) and the friction angle (φ). The validation of these two stochastic optimization methods is done on the experimental sheet pile wall of Hochstetten in Germany. The results obtained by applying the genetic algorithm method and the hybrid genetic algorithm method for the identification of the two Mohr-Coulomb parameters (G, φ) show that the hybridization process of the genetic algorithm combined with the Tabu search method accelerated the convergence of the algorithm to the exact solution of the problem whereas the genetic algorithm alone takes a much longer computation time to reach the exact solution of the problem.

This research is oriented towards the valorisation of local materials and the reduction of energy consumption with the aim of judicious use of these materials. In front of the world economic crisis, that also affects our region, it is necessary to solve the problem of pollution and enable important links for the balance with nature. In Algeria, buildings are very inefficient in terms of energy use and therefore remain a major source of energy consumption. To reduce this consumption and improve the thermal comfort of a building and save energy, it is necessary to use particularly high-performance materials that ensure good thermal insulation. The objective set in this work is to study the thermal behaviour of walls of different compositions, in order to identify those that allow the greatest energy savings in the case of air-conditioning for the Saharan context. The results proved that it is possible to use local materials to reduce energy consumption by 50% and save energy, improve the performance of the construction, and ensure the thermal comfort of buildings.

The building industry, like many other industries, is driven to take a significant turn due to the pressing issue of global climate change. The potential in digital technologies and digital design approaches is pushed forward and exploited in architecture, structural, civil, and geotechnical engineering. The challenges such as the overheating of buildings and urban spaces, lack of drinking water, expensive and environment-aggressive building materials, and many more are investigated in more depth in Volume 17 of the Selected Scientific Papers - Journal of Civil Engineering.