Accepted Papers to Appear in Future Issues

Enhanced soft computing for ensemble approach to estimate the compressive strength of high strength concrete
Munish Kumar, Parveen Sihag, Varun Singh

High strength concrete (HCS) define as the concrete that meets unique mixture of performance uniformity requirements that cannot be reached routinely using conventional constituents and regular mixing, placing, and curing events. The modeling of such type of concrete is very difficult. In this investigation, the performance of the gaussian process (GP) regression, support vector Machine (SVM) and artificial neural network (ANN) were compared to estimate the 28th day compressive strength of the HSC. Total data set consists of 83 data out of which 70 % of total dataset used to train the model and residual 30% used to test the models. The model accuracy was depend upon the five performance evaluation parameter which were correlation coefficient (R), Bias, mean square error (MAE), root mean square error (RMSE) and Nash-Sutcliffe model efficiency (E). The results recommend that ANN model is more accurate to predict the compressive strength as compare to GP and SVM based models. Sensitivity analysis indicated that Cement (C), Silica fume (SF), Fly ash (FA) and Water (W) are the most valuable constituents in which compressive strength of the HCS is mainly depend for this data set.
Date accepted : 2018-12-21

Rachid Bouras, Chafiaa Si Hadj Mohand, Mohammed Sonebi

An adhesive mortar in fresh state is considered as a granular suspension in a complex fluid. The study of the rheological behavior of such materials involves the rheology of complex fluids, including granular suspensions, colloidal dispersions, etc... To characterize the rheological behavior of an adhesive mortar, in quasi-static regime, we use a three-parameter behavior law that includes a yield stress, a viscosity coefficient and a fluidity index. The adhesiveness of the mortar can be characterized by identifying the evolution of the adhesive force [ these phan] , the cohesive force and the adherence force. The mortar characteristics are measured by a commercial rheometer from Texas Instruments (TA). In this study, we use a plane-plane geometry for the Probe Tack Test to determine the adhesiveness of the materials. The rheological property of the mortar is investigated using the Vane-Cylinder geometry (figure 1.5). The mechanisms of separation and rupture in a tensile material confined between two parallel plates are studied theoretically and experimentally. This study is conducted for a materials selected for his rheological behavior (Herschel Buckley). We studied the rheological behavior and the influence of additions of organic additives on the rheological parameters intrinsic to the material, and the failure mechanisms. This study has allowed us to observe the different types of rupture. This indicates that these materials are neither adhesive failure nor cohesive failure.
Date accepted : 2018-12-10

Etude expérimentale de l’effet du processus électro-osmotique dans un sol fin salin de la région de Mostaganem

L'électro-osmose est une technique utilisée comme moyen de déshydratation et traitement des sols fins, en génie civil et en génie de l’environnement pour l’amélioration et la dépollution des sols, ainsi qu’en agriculture pour la désalinisation des sols. Son efficacité dépend de la nature du sol traité. Le traitement électrocinétique est une méthode qui utilise un courant électrique de faible intensité, ou une faible différence de potentiel électrique pour générer un flux hydrique. Dans cette étude, l'effet de ce processus d’électro-osmose sur les propriétés d'un sol fin de la région d’Ain Nouissy (Mostaganem –Algérie) sous une différence de potentiel électrique a été analysé.
L’objectif est d’étudier le comportement de l’écoulement hydrique et la modification de certains paramètres, tels que la conductivité électrique, le pH ou les limites d’Atterberg durant et après le processus électrocinétique. Ces paramètres permettent de comprendre et de contrôler la performance de cette technique vis-à-vis du traitement considéré. Le chauffage du sol durant le processus électrocinétique a été abordé à travers la température de surface, indiquant une perte d’énergie relative lorsque le gradient de tension dépasse une valeur optimale.
Date accepted : 2018-07-26

Elaboration of geopolymer cement based on dredged sediment
Fouzia MOSTEFA, Nasr-Eddine BOUHAMOU, Habib MESBAH, Salima AGGOUNE

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria). Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1. Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.
Date accepted : 2018-10-25

The Influence of Deformability of Horizontal Diaphragms in the Distribution of Seismic Loads to Bracing Elements in Rectangular Buildings

The operations of a floor, as a significant structural element, have an influence on the stability of the structure when it acts as a horizontal diaphragm. In this study, the in-plane deformability of rectangular floors of single story buildings is examined under the effects of horizontal seismic actions. Therefore, the effects of parameters influencing the behavior of the floor such as size opening and their location, position of shear walls, span-to-depth ratio, and materials constituting the floor were studied. Results suggest that a diaphragm will behave in a flexible manner whether it is classified as rigid or flexible. However, a small opening in the floor can change the behavior of a diaphragm assumed rigid and make it behave like a flexible diaphragm. Additionally, flexible diaphragms can distribute horizontal seismic shear forces to vertical resisting elements due to the relative rigidity of the shear wall. These results are in contradiction with seismic codes such as ASCE/SEI 7-10 [1], FEMA 356 [2], and Eurocode 8[3], further the size of opening that make flexible diaphragm behave like rigid diaphragm was suggested by formula. For the building with a shear wall, the classification of the diaphragm in seismic codes such ASCE is not accurate enough and they need to reform with taking into consideration the location of the opening in the floor.
Date accepted : 2018-12-29

Experimental and numerical analysis of the fields of the frozen stresses in an epoxy sphere using the method of freezing mechanical cutting

Kamel TOUAHIR, Ali BILEK, Philippe BOCHER, Mustapha BELDI

The stresses induced by a mechanical contact imposed on a sphere have been studied experimentally and numerically. The technique of freezing and mechanical cutting in thin slices was used. Slices are analyzed on a polariscope using plane light and circular light. The photoelastic fringes are used to determine the principal directions of the stresses as well as the values of the stresses. A numerical simulation using the finite elements made it possible to make a comparison with the experimental results. The analysis shows a good correlation between experimental measurements and numerical simulation.
Date accepted : 2018-12-25

Durabilité des ciments Portland composés de fillers de déchets industriels dans un milieu acide
Mohammed EZZIANE, Ibrahim MESSAOUDENE, Laurent MOLEZ

Ce travail expérimental étudie la durabilité de mortiers réalisés avec un ciment Portland composé de fillers industriels : laitier granulé et poudre de marbre. Les échantillons sont conservés durant 12 mois dans l’acide sulfurique. L’évolution des phases cristallines est suivie par diffraction X et les minéraux sont observés au MEB, la microanalyse qui lui est associée permet de confirmer leur composition chimique. Les résultats montrent qu’à une concentration de 0,05M, les hydrates du ciment (CSH, CH, ettringite) ne semblent pas affectés à l’intérieur de l’échantillon, le soufre est y totalement absent. En revanche, les mortiers exposés à une forte concentration (0,25M) en acide sulfurique développent un dépôt extérieur dense de gypse. Le mécanisme de l'attaque est principalement dû à l'action expansible du gypse.
Date accepted : 2018-11-05

Protection of structures subject to seismic and mechanical vibrations using periodical networks
Amine AMRANE, Nouredine BOURAHLA, Abdelkader HASSEIN-BEY, Abedelkrim KHELIF

The concept of frequency gaps in phononic crystals is widely used in physics. The feasibility and efficiency of applying this principle in damping out seismic and mechanical induced vibrations in real scale of civil engineering constructions are presented in this article through the results obtained from numerical modeling and analysis of a concrete substratum embedding steel elements (pillars) coated in a polyvinyl chloride polymer (PVC). The first configuration having the elements fully embedded into the substrate resulted in two narrow band gaps at relatively high frequencies; and when only the metallic pillars are emerging from the substrate, the band gaps shift towards the low frequencies. The results are improved and show the existence of three band gaps at medium frequencies ranging from 80 to 200 m/s when both the pillars and the polymer are emerging from the foundation. Exploring other metal-polymer pairs of materials such as "steel-rubber", "steel-silicone"," lead-rubber" and "lead-silicone", shows that a range of band gaps has shifted again towards the lower frequencies which cover part of the seismic frequency domain. Further improvement are obtained by notching the ends of the substrate in order to widen and lower the band gaps especially for "metal-rubber" pairs. These results show the potential of using periodic networks to mitigate seismic and mechanical vibration effects on large scale structures and components.
Date accepted : 2018-12-04

Mechanical Behaviour of Corrugated Laminates
David J.G. Pinheiro, Maria Amélia R. Loja, Inês C.J. Barbosa, João Milho

The present research work intends to perform a wide set of structural analyses upon corrugated composite laminated panels and based on these analyses to assess their mechanical response in correspondence to the constructive solutions, which may range from the composite materials selection to the geometrical features and other modelling parameters. To improve the mechanical performance of those panels one may consider enhancing their geometrical characteristics, their corrugation shape configuration and the materials used to build them. In this latter case, when considering materials selection, laminated composites may also constitute an important alternative. In any case it is considered necessary to assess the impact that each of these parameters may have in the static and in the free vibration behaviour of the structures, in a comprehensive and detailed way. To achieve the main objective of this research work, a comprehensive and diversified set of case studies is considered in order to characterize the influence that each of the modelling, material and geometrical parameters and characteristics may have in the mechanical response of a corrugated panel. This study allowed concluding that for the wide set of design parameters considered, the fibre orientation and corrugation parameters are the ones that show to be responsible for the majority of the significantly improved performances.
Date accepted : 2018-12-18

Effects of Poly Vinyl Acetate on Characteristics of Expansive Soil

Soil stabilization using polymer materials has become of great potential in recent years. In this regard, an attempt is made to investigate and understand the influence of Poly Vinyl Acetate (PVA) on the engineering properties of expansive soil. A series of treated soil specimens were prepared and tested at four different percentages of PVA (0%, 1.5%, 3.75%, and 5% by weight of dry soil). These treated specimens were subjected to laboratory testing for measuring Atterberg limits, free swell, compaction characteristics, and unconfined compression strength properties. It was found that PVA had significant influence on the properties of treated soil. An increase in PVA content resulted in an increment of unconfined compressive strength of the soil. Addition of 3.75% of PVA increased the unconfined compressive strength value almost 6 times the value of the virgin soil. On the other hand, an increase in PVA content led to a reduction of free swell and plasticity index. The soil plasticity and free swell indices values were reduced from 62% to 0% and from 190% to 50% respectively by addition of 5% PVA. It can be concluded that an increasing trend for soil strength and decreasing in swelling with addition of PVA, suggesting its potential applications in stabilization of expansive soils.
Date accepted : 2018-12-30

Reliability assessment of frame steel considering semi-rigid connections

Initial stiffness and Moment resistance are two parameters that make up the hardness of between columns and beams connection in frame steel. This problem has been studied based on empirical values and connecting method of many authors. In this research been used Initial stiffness and Moment resistance models for reliability assessment of frame steel under the internal force of semi-rigid joints when random input parameters. A stochastic model for the design of frame steel considering semi-rigid and Monte Carlo reliability analysis. This program is written by using the Matlab programming language and author’s surveys numerical and conclusions and recommendations.
Date accepted : 2019-01-11

Parametric study with FE model of cold-formed plain lipped C-section in shear, and combined bending and shear
Tabassum Mahzabeen RAKA, Khan Mahmud AMANAT

The study focuses on the finite element (FE) modelling of cold formed plain lipped C-section in shear, and combined bending and shear, which was developed using ANSYS. Hence, a parametric study on plain C-section was conducted to investigate the applicability of the direct strength method (DSM). In addition, DSM capacity curves were constructed to find out the limitations of DSM. It is found that the DSM equations for nominal shear capacity with tension field action (TFA) gives the capacity that is acceptable when full tension field action is developed while the nominal DSM moment capacity at local buckling outlines conservative results. However, the study also reveals that the DSM nominal shear capacity without tension field action provides lower capacity than the real peak capacity and therefore, it concludes that this method is more conservative.
Date accepted : 2019-01-02

Seismic performance of mid-rise code-conforming X-braced steel frames
Mokhtar ANSARI, Hosein Gholi POUR, Amir SAFIEY

Prolixity and complexities inherent in non-linear dynamic analysis (NDA) impels engineers to lean towards nonlinear static analysis (NSA) in practice. This paper partly explores differences and similarities in responses obtained from these two simulation techniques. The scope of study is narrowed down to ubiquitous regular code-conforming mid-rise steel X-braced frames. Different common lateral load patterns are coupled with NSA to study their interactive effects on responses. Modal nonlinear static analysis is also carried out, where deemed necessary. NDA using three different earthquake records are conducted as well, to validate NSA results. Results of nonlinear analyses are undertaken to compare provisions of seismic rehabilitation code with those of seismic design codes. Base shear, story drift, lateral displacement profile obtained for each model are independently thoroughly discussed. Eventually, some suggestions to improve design code requirements are accordingly provided, as applicable.
Date accepted : 2018-12-08

Study of Mortars Made with Natural and Artificial Pozzolans

The objective of this work is to evaluate the thermal activation potential of clay soils, particularly the clay fraction of dam mud, for the production of artificial pozzolan which can be substituted to cement in concrete and mortars applications and also to make a comparative study with the natural pozzolan available in the area of Beni Saf in considerable quantities. The research study is carried out on three mortars 10, 20 and 30% of natural pozzolan of Beni Saf and artificial pozzolan from the mud calcined at 850 ° C / 3 hours of the dredged sediments of the dams of Fergoug and Ouizert, and on a control mortar without additions for the need of comparison. Several physical, mechanical, microstructural and sustainable tests have been carried out to carry out this research study: maneuverability in the fresh state, impeded shrinkage, mechanical performance, absorption, acid attack (5% CH3COOH, 5% HNO3 and 5% H2SO4), mass loss and pH reading follow-up in the hardened state. Compressive strengths indicate that pozzolan-based mortars have the best results in particular over the long term, whereas the results of acid attack tests show that the calcined mud has a significantly greater influence than natural pozzolan.
Date accepted : 2018-12-10

Use of crushed clay brick waste as dune sand granular corrector in mortar manufacturing
Abderrahmane Ghrieb, Yacine Abadou

The purpose of this work is to use the crushed clay brick waste to make it a useful material for correcting dune sand granulometry, in order to manufacture with them mortars with satisfactory performance in terms of consistency, compactness, mechanical strength and resistance to aggressive agents. The mixtures composition method is based on the progressive substitution of dune sand with crushed waste at different weight contents; 5, 10, 15, 20 and 25%. The results obtained show that the incorporation of the used waste has a significant influence on the behavior of the mortar, in the fresh state and the hardened state. Further to this, it has also been observed that its inclusion with certain percentages makes it possible to obtain performances comparable to those of the alluvial sand-based mortar, which demonstrates its effectiveness in improving the various properties of the mortar.
Date accepted : 2019-01-15

Numerical Analysis of the Tetrapylon Roman's Triumphal Arch of Tebessa: A Case Study.
Ahmed Rouili, Mabrouk Touahmia

The Tetrapylon Roman Triumphal Arch or commonly called 'Caracalla Gate', located in Tebessa City (Northern Algeria), is considered as one of the most distinctive type of arches associated with the ancient Roman's architecture. This historical monument, erected in the 3rd century, was dedicated to the Roman Emperor Caracalla. In the 6th Century the Caracalla gate was enclosed in the Byzantine old city, built by the General Salomon. Although the monument is still standing, over time, it suffered apparent damages. The conservation and restoration of this monument is actually a major preoccupation for the concerned authorities. In this paper a 3D numerical analysis of the deformations and global stability of the gate are presented. The numerical results obtained were compared to previous site survey and measurements, and were found to be in good agreement. The results revealed that part of the monument damages and deformations occurred following the construction of the Byzantine walls. In its actual state, the monument was found sufficiently stable, and the restoration would not affect its firmness, if appropriate materials and techniques are deployed.
Date accepted : 2019-01-15

Contribution to Probabilistic Modeling of Soil Geo-mechanical Properties for Structural Reliability Analysis of Shallow Foundations
KAZI TANI Nabil, NEDJAR Djamel, TAMINE Tawfik, HAMANE Mabrouk

This present study synthesizes a numerical approach to optimize foundation systems design and underground pipes based on the combination of elasto-plastic soil behavior and probabilistic modeling of its geo-mechanical characteristics. Also, this work allows quantifying the effects of soil spatial variability on the mechanical and structural reliability of civil engineering infrastructures anchored at shallow depths in the ground. The illustrated simulations are based on simultaneous combination of the elasto-plastic soil behavior and its spatial variability, which allow to describe accurately the mechanical behavior of civil engineering infrastructures in complex environments.
Date accepted : 2019-01-20

Development and Characterization of E-Glass Particulate Reinforced Epoxy Composite for Automobile Application
Johnson Olumuyiwa Agunsoye

The structure and mechanical properties of epoxy composites reinforced with E-glass particles have been evaluated to assess the possibility of using the composite as a new material for car bumper fabrication. Epoxy resin of the type LY556 reinforced with 5 – 25% of E-glass particles added at 5% intervals was investigated. The fabrication of E-glass particle reinforced epoxy composite was successful and a prototype car bumper was made. The newly developed E-Glass particles/epoxy composites were characterized for their mechanical and structural properties using Thermo-Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), X-Ray Diffraction Analysis (XRD), Tensile, Flexural, and Impact tests. The results showed that 20 wt. % glass particle addition gave the ultimate mechanical properties with tensile and flexural strengths of 154.5 and 181.55 MPa respectively. SEM morphology had also shown good adhesion between fibers and polymer matrix up to 20 wt. % glass particle addition with minimal segregation of reinforcement glass particles. Thermal stability of the composite was not impaired going by a stable degradation temperature (Td) after E-glass particles addition. A prototype bumper was fabricated from epoxy-15 wt% E glass particle composite possessing peak impact energy.
Date accepted : 2019-01-20

Etude expérimentale de la réparation des structures d'aéronefs par collage des patchs à base d’époxy et fibre de verre
Djamel Basaid, Abdelbaki Benmounah, Chouaib Aribi, Abdelghani May

The composite materials present weakness to shocks and impact caused by different projectiles (Foreign Object damage, birds, lightning ....), Studies are carried out in order to minimize the consequences of these defects solutions are adopted for temporary or permanent repairs existing as procedures in a manual called SRM (manual repair structure). This experimental work carried out at the University of Boumerdes in collaboration with AIR ALGERIE airlines. This paper aims to study some cases of repair of aircraft structures. These repairs are applied to the defects present on the composite materials of the "Low Energy Impact" type aircraft structure using the Epoxy matrix composite patch method: EPOCASTA50-1, a non-diluted resin reinforced with glass of the same type as that of the aircraft fuselage. Then, the effectiveness of these repairs is verified using the study of conventional tensile behavior by applying a stress of the order of 80% of maximum stress, in relaxation mode. For the characterization of the damaged state and validation of our results we used the method of non-destructive NDT control based on ultrasound, this verification is carried out on specimens developed under the same conditions as repair plates attached to the fuselage plane.
Date accepted : 2019-01-20

Experimental study of the long-term shortening of reinforced concrete columns under maintaining concentric axial load
Ngoc Long TRAN, The Truyen TRAN, Manh Hung NGUYEN, Van Quyet TRUONG

This paper presents the results of an experimental study to measure the shortening of reinforced concrete (RC) columns under long-term maintaining concentric axial load. Long-term axial deformation due to shrinkage and creep of the concrete were recorded beside deformation due to mechanical load. Eight RC cylinder - columns (content of reinforcement 1.5% and 2%) with diameter of 150 mm and height of 600 mm were tested during the period of 600 days to determine their shortening. The experimental results showed that the long-term deformation of RC columns occurs primarily during the first year of loading. The deformation creep of concrete is much greater than the shrinkage deformation. The reinforcement content has a significant effect on the long-term deformation of concrete columns.
Date accepted : 2019-01-27

Comparison between DRF for displacement and acceleration spectra with uncertain damping for EC8
baizid benahmed, Abbas Moustafa

A damping reduction factor (DRF) is used to estimate high damping response spectra from their 5% counterpart. DRF has been studied by many researchers using mathematical relations as function of damping ratio xi and natural period T, are available in the literature which have been implemented in the seismic codes worldwide.
The damping force experienced by a building during an earthquake differs significantly from the value specified in the design process. This introduces uncertainties in the design process of buildings under earthquake loads. Accordingly, it is desirable to consider not only the effects of uncertainties in loading but also the uncertainties in the structural parameters. The aim of this work investigates the effects of uncertainties inherent on damping ratio on the use of DRF for the evaluation of high damping response spectra. The DRF values are evaluated from both acceleration and displacement response spectra. Effects of period of vibration, level of damping ratio and site class and the level of uncertainties of damping on the DRFs are evaluated and discussed. The damping uncertainties are represented by a lognormal probability distribution function and the Monte Carlo Simulation (MCS) technique is used to generate the random values of xi .
First, three sets of natural records, compatible (on average) with the EC-8 response spectra have been selected in accordance with the Europeen seismic code EC8 Afterwards, the selected records have been used to derive response spectra with uncertain dampings through response history analysis for the displacement and the acceleration responses. Finally, a comparison between these approaches was presented and important conclusions were attired on the light of the results obtained.
Date accepted : 2019-02-01

Mechanical and structural reliability based algorithm optimization

The overall aim of this paper is the development of nonlinear formulations of BEM (Boundary Element method) for the analysis of fracture problems and also the realization of a probabilistic approach to the fatigue problem through the coupling between a mechanical model that deals with the propagation of cracks under fatigue, and structural reliability models. On the BEM/MEF coupling model, the crack propagation model was introduced on a linear elastic regime. This model leads to interesting results and allows to analyse some structures where this effect is important. Closing the topic related to the development of BEM formulations, a formulation was also developed for the analysis of fatigue cracking propagation problems. Probabilistic models are applied to the analysis of structures submitted to fatigue. It is known that the integrity of the structures in service essentially depends on its ability to maintain a resistance pattern over time. To this probabilistic model was coupled an optimization algorithm for the determination of parameters such as the geometry dimensions of the structure as well as intervals for the performance of the maintenance and inspection procedures, taking into account objective functions written in terms of structural cost and safety. The investigation shows that direct coupling scheme converged for all problems studied, irrespective of the problem nonlinearity.
Date accepted : 2019-02-04

Evaluation of Fatigue Limit and Mechanism of Fatigue Crack Initiation of Epoxy Coatings used as Lining for Crude Oil Storage Tanks
Haider Hadi Jasim

In this paper, the fatigue performance of three types of epoxy coatings (pure, Novolac and reinforced by glass-flake) were studied in crude oils and air environments. A group of equipment is constructed in a laboratory and used in rotating bending fatigue tests of single and double layers of coats applied to ASTM A537-C1 steel. The results showed that the fatigue limit of A537 steel improved after coatings and that the fatigue limits of the coated and uncoated steel conducted in the crude oil solution was significantly lower than those obtained in the air environment. The results of the microscopic inspection indicate that there are three types of fatigue cracks initiation mechanism in steel coatings and environment affects the shape of fracture surface. In addition, the observation of the broken section of the single-layer test sample showed that it has more coat failure compared to the double layers coats.
Date accepted : 2019-02-18