Browse

71 - 80 of 80 items :

  • Engineering, other x
  • Materials Sciences, other x
  • Introductions and Overviews x
Clear All
The Reflective Cracking in Flexible Pavements

Abstract

Reflective cracking is a major concern for engineers facing the problem of road maintenance and rehabilitation. The problem appears due to the presence of cracks in the old pavement layers that propagate into the pavement overlay layer when traffic load passes over the cracks and due to the temperature variation. The stress concentration in the overlay just above the existing cracks is responsible for the appearance and crack propagation throughout the overlay. The analysis of the reflective cracking phenomenon is usually made by numerical modeling simulating the presence of cracks in the existing pavement and the stress concentration in the crack tip is assessed to predict either the cracking propagation rate or the expected fatigue life of the overlay. Numerical modeling to study reflective cracking is made by simulating one crack in the existing pavement and the loading is usually applied considering the shear mode of crack opening. Sometimes the simulation considers the mode I of crack opening, mainly when temperature effects are predominant.

Open access
Steel-Concrete Viaducts in the Orastie-Sibiu Highway: a Eurocode Compliant Project

Abstract

This paper is intended to show the design of two composite bridges along the Orastie- Sibiu motorway, from the basic concepts, applied without the need for a clause-by- clause checking of codes and standards, to the construction methods.

The bridges are seismically isolated in the longitudinal direction, while transversally the seismic action is distributed among the piers.

Calculations have been carried out through state of the art procedures, taking into account form effect of the cross section. For this reason, different FE models have been set up to study different aspects of the behavior, with increasing degrees of approximation. For example, “beam” elements have been utilised to investigate global effects both in the linear and non linear range, while more accuate 2D and 3D elements have been used for refined cases such as stress checks and local buckling analyses.

The present paper goes into detail in particular for what concerns some of the most interesting parts of the design process for the specific case. Namely, time dependent properties of the materials have been considered, and extensive “staged construction” analyses have been carried out to ensure safety in each phase of the complex life of the bridges, while at the same time guaranteeing significant cost savings.

Open access
Sustainable Urban Transport Planning

Abstract

Environmental protection has become a common issue in every area, but extremely important for the domains which deal with intensive energy consumption as it is the case of the transportation. Achieving the sustainable cities on the other hand, is also focused on the protection of the environment in order to provide a higher quality of life for the population. Therefore it is considered that by improving the urban transportation planning additional benefits could be provided for both the environment and the sustainable development of the cities. One possibility is to supplement the traditionally land-use plans with the transportrelated zones analysis, where the city is divided in public transport, pedestrian and caroriented zones. Analyzing the transport-related zones of a city is important as it provides additional information in the assessment of the development trend. The process of zoning was conducted for the city of Cluj-Napoca, Romania. In this paper, the outcome of the zoning was analyzed for a more comprehensive review of the urban transport in order to attain a sustainable-oriented approach of the urban area development.

Open access
Asphalt Mixtures with Limestone Aggregate for Base Layer

Abstract

Asphalt mixtures are mixtures of mineral aggregates, filler, bitumen and eventually additives in proportions determined by recipe designed in the laboratory. Asphalt mixtures used as base course are bituminous concrete.

The natural aggregates are granular materials of mineral origin that come from natural or artificial crushing of the rocks. In our country there are the various rocks: eruptive or magmatic rocks, metamorphic rocks, sedimentary rocks.

To the category of sedimentary rocks belong limestone. Sedimentary rocks are characterized by relatively high porosity and a pronounced stratification, which causes mechanical resistance to be low and vary by direction of load. Due to the structure less dense and weaker mechanical resistance, the limestone are used less in heavy traffic pavement structures.

This paper presents an asphalt mixture recipe for the base layer developed in the Laboratory of Roads from Technical University of Civil Engineering Bucharest (TUCEB), using limestone aggregates extracted from Hoghiz Quarry. The paper contains laboratory test results to determine the recipe and laboratory findings leading to the schedule of product.

Open access
The Distance Between Real Time Data and Decision Making in Urban Road Freight Transportation Systems; The Example of the City of Thessaloniki

Abstract

Road freight transport in urban areas (city logistics) is under study worldwide, especially during the last years, mainly due to its negative impacts to the environment and to the efficient operation of the road network. The modern approach to deal with this rising issue includes the deployment of strategies and measures that take into consideration the conditions prevailing in each study area. In order the decision makers to adopt the proper measures and define the strategy, it is vital for them to have full knowledge of the way an Urban Road Freight Transportation (URFT) system is organized and functions in the field. For this to happen, the decision makers must have under their disposal reliable real time data. After all URFT systems evolve through time and space and it is s crucial that the necessary data not only will be collected correctly but also they will be accessible anytime and anywhere. In this paper a new approach is proposed in order to achieve real time monitoring for URFT systems in order to provide the decision makers with all the necessary data for the case of Greece.

Open access
Microfibre Reinforced Hot Mix Asphalt

Abstract

Cracks are common disturbances in pavement structure. The ability of hot mix asphalt to withstand tensile stresses is limited. This paper presents influence of different microfiber reinforcement types ITERFIBRA to hot mix asphalt behaviour in its chosen properties. Bulk density of hot mix asphalt, stiffness , resistance to the permanent deformation and resistance to the crack propagation are taken into consideration.

Open access
Some Investigations Performed for the Bridge Over Jiu at Aninoasa

Abstract

The carrying structure of the bridge over the Jiu River at Aninoasa consists in two parallel concrete arches with variable height of the cross section, sustaining a concrete deck through vertical concrete hangers. In the time period passed since the bridge was erected, some structural elements shown damages. In order to establish the technical state of the bridge, a technical appraisement was performed and according to this, the most exposed elements to the risk of failure are the hangers.

The purpose of this paper is to present briefly both, the method used to test the actual bridge carrying capacity in situ and the finite element model developed for the static and dynamic analysis of the structure.

In order to estimate the state of the structural elements, two ways were followed. In the first stage, a test project was carried out and in the second stage, a complete 3D finite element model was developed to analyze the bridge structure.

The test project has foreseen the loading of the bridge by heavy unloaded trucks, disposed in some positions on the deck and the measurements of the deck and arches displacements. The positions of the trucks were established in order to obtain the maximum values both for arches transverse displacements and vertical displacements of the deck. Using electro-resistive transducers the hangers elongations and strains values on their cross section were also measured. These measured values were compared with those obtained from the numerical calculations performed by using the complete finite element model. By means of the finite element model, also the response of the structure following the dynamic action of vehicles was investigated.

Open access
Traffic Lights on Consecutive Intersections and Pedestrian Crossings Along Linear Settlements Located on National Roads

Abstract

In Romania, with time, settlements located along the main roads have developed and transformed into linear towns, with significant local and connection traffic, important administrative, economic, commercial and touristic activities concentrated in the central area, as well as pedestrian traffic of over 200 pedestrians per hour in the main pedestrian crossings on the route.

The object of the present study is made by a series of junctions situated on National Road 1 in Busteni town, on a dangerous road sector. For this study, traffic measurements, simulations and suggestions for improving the existing situation were made.

Based on the simulated traffic flows, there were performed capacity analysis with PTV Vissim and Traficware Synchro softwares, and were developed appropriate planning solutions for the intersections, resulting in tables with extracted performance indicators based on micro simulation of the traffic values. Also planning solutions for horizontal design and proposals for traffic lights were made for junctions that can not operate under priority traffic on one direction or which are presenting traffic safety risk.

Based on the traffic data, it was taken in consideration the necessity to make planning proposals and to develop design solutions immediately applicable, with minimum intervention.

Solutions will refer to the geometric planning of the intersections, but with new plans and timings for traffic lights, including proposals for new equipment; regulating the traffic flow: development/ refurbishment of intersections and pedestrian crossings; optimization of routing programs in order to achieve a higher level of service and more efficient traffic control indicators; segregation of pedestrian movements by vehicles traffic, implementation of physical devices to lock / channel the traffic.

Open access
Transport Demand Forecast on Pan-European Road Corridor X. Methodology, Results and their Assessment Through Comparisons with Actual Demand

Abstract

Transport demand forecast is a crucial parameter for transport planning. It defines the infrastructure dimensioning for a required level of service in a planning period, but moreover, it is determinative in the socioeconomic and financial feasibility study of transport projects. This paper presents the methodology and the results of the traffic flows forecasting exercise for the Pan-European Corridor X, which was elaborated to serve as a sound basis for documentation of the transport investments priorities, and the assessment of the results of the forecasted demand through comparisons with actual demand.

Open access
Romanian Journal of Transport Infrastructure
The Journal of Technical University of Civil Engineering Bucharest
Open access