Journal of Building Materials and Structures

Design and Construction Criteria of Twin Tunnel: Taking an Adverse Wind Condition Effects on Air Pollution Short Circuit at Tunnel Portals as a case

2020-03-30T20:41:08+00:00

This paper aims to study the influence of the tunnel portal designs, wind conditions and ventilation rate on the amount of air pollution short circuit from one tunnel tube to the other. These effects are investigated by Computational Fluid Dynamics (CFD) code used a Large Eddy Simulation (LES) method to control air quality inside the tunnel and reduced as far as possible a short circuited (flow Recirculation) flow level. A validation of CFD code to experimental data in 1:100 scale model of the road traffic tunnel tested in wind-tunnel showed that the CFD gave satisfactory prediction of the air pollution short circuit in the vicinity of tunnel portal. The predicted concentration of the gas tracer (CO₂) used as the safety criterion provide the useful information about a short circuit amount resulted for each structural variant of tunnel portals, such as a central dividing wall built as extensions from the end of road tunnel and offset tunnel portal entrance exit tested under different speed ratio of wind and ventilation. A detailed look at results is beyond the scope of analysis to determine optimal air pollution short circuit percentages. Finally, the perfect tunnel portals geometry can be suggested.

Comparative design procedures of stone columns for liquefaction stabilization

2020-05-16T11:46:14+00:00

Soil liquefaction is one of the most important and complex phenomena of soil dynamics. It is a loss of résistance of loose granular soils under a seismic shock.

The aim of this work is to study the improvement made on a liquefiable soil using a stone column solution by several methods namely observational, static and dynamic solutions. The site used for this application is located in a terminal port container in Algiers. The analysis was carried out using the test results of standard penetration and cone penetrometer tests completed during a site investigation.

A comparative study between the methods was carried out to determine the most suitable method. The results of the 3 methods showed that the sizing by taking into account the earthquake, the mesh of stone columns is denser. It was deduced that it is important to analyze by the dynamic method in seismic zones and by static or observational techniques in areas of no or low risk of liquefaction. Recommendation for further research was put forward to develop new tools in order to improve current design methods.

Valorization of calcined kaolinitic clay used in high performance mortar

2020-05-16T11:45:03+00:00

In this work, an experimental investigation was carried out to evaluate the potential of an industrial pozzolan, the metakaolin, on the behavior of mortar. The aim is to use metakaolin as a 10% partial replacement of cement. Its effect on the physico-mechanical properties of the mortar has been analyzed. The results show that the incorporation of metakaolin decreases the density of the dried mortar and increases that of the wet mortar but these remain lower than those of the control mortar. Moreover, thermal analysis ATD / ATG shows that in the heat flow curve appears two endothermic peaks which correspond to the loss of mass of the cement pastes. Heat flux of these pastes increases when metakaolin is used into the cement. In addition, metakaolin increases the compressive and flexural strengths of wet and dry mortars by approaching without exceeding those of the control mortar. The use of metakaolin as a cement substitution has shown its potential to be a pozzolanic material that can offer economic, environmental and technical benefits.

Stabilization of compressed earth block clayey materials from Adrar (Algeria) by lime and crushed sand

2020-05-16T11:44:51+00:00

The objective of this article is to determine the physical and mechanical properties of stabilized compressed earth bricks (SCEB), made from a mixture of clay with crushed sand, and stabilized by lime. In this study, we first examine the identifying properties of raw materials. Then an experimental study was conducted with cylindrical test pieces of a mixture of clay and crushed sand prepared by the addition of lime and statically compaction, to study the physical and mechanical characteristics of the mixture. The experimental study shows that for use as a building material, the clay mixture with 30% crushed sand and stabilized with 4% and 6% lime is the optimum mixture for as a stabilized compressed earth bricks.

Optimal seismic response using a Passive Tuned Mass Damper Inerter (TMDI)

2020-05-16T11:44:52+00:00

The latest earthquakes history shows that resistant conception, safe and economical structures are a daily challenge for structural engineers. Among the newest vibration control devices figures the inerter which is a device which can develop a large fictive mass (it consists of a mass amplification effect) using rotational inertia. In this research work, the effectiveness of a traditional passive tuned mass damper (TMD) is compared with a tuned mass damper inerter (TMDI) which consists generally of tuned mass damper coupled with an Inerter. Both devices are used to control a base-isolated structure vibration submitted to several seismic records. In This study, a base-isolated structure of six stories (6 DOF) was equipped with (TMD) and (TMDI) and a time history analysis were performed under different earthquake records (El Centro, Kobe, Kocaeli). The mathematical model of the building is established in MATLAB Simulink. The simulation results illustrated he robustness, performance and effectiveness of the structure equipped with a (TMDI). The dynamical parameters of interest were base and top displacement as well as the base shear force and peak inerter force produced.

Pathology Evaluation and Repair of Bridges in Masonry

2020-05-16T11:44:12+00:00

The field of repair and rehabilitation of civil engineering works is evolving. Indeed, most of these structures, especially masonry structures, are over 50 years old and many of them require maintenance and repair work due to their deteriorated condition. To achieve this objective, a study was carried out concerning the different pathologies affecting the masonry bridges, but also the ways and means necessary for the evaluation and repair of the affected works. The results of this work have not only helped to carry out the diagnosis and verification of the structural state of the bridge over river Kentra Stora Skikda (North-East of Algeria), on the section of the 3AA National Road Skikda, but also for the proposal of repair solutions best adapted to the disorders observed.