<abstract xmlns="http://www.w3.org/1999/xhtml">This paper presents a new type of seismic isolator that uses the principle of electromagnetic attraction and repulsion, to control the friction force between two electromagnets during earthquakes. The two electromagnets are used in conjunction with a secondary high friction dissipating and damping mechanism composed from a 10mm thick neoprene ring layer and two steel surfaces coated with Si3N4 that are used to dissipate the kinetic energy in the bridge deck at some maximum ground accelerations. The isolator utilizes tri-axial accelerometers embedded in the abutments, high current rechargeable batteries and an automated controlling unit. The presented isolator was developed specifically for a concrete bridge deck with a span of 36 meters and simple supported on two abutments, using time history electromagnetic and structural analyses. The paper presents the advantages of using this active seismic isolation system, compared to classical passive devices and the important results obtained in terms of decreasing internal forces on the substructure elements cross sections together with the reduction of relative displacements between the two electromagnets.</abstract>

Technical University of Civil Engineering Bucharest

Technical University of Civil Engineering

Strength of Materials, Bridges and Tunnels Department

Seismic Isolation of Bridges Using the Principle of Electromagnetic Attraction and Repulsion

<abstract xmlns="http://www.w3.org/1999/xhtml">Dynamic testing of bridges has as target to establish their response on pulse forces between the wheels and unevenness of road surface. Generally, during the tests, real time accelerations or deformations are to be measured and which through successive processing methods lead to other data as velocities, displacements, dynamic impact factor, but also the damping ratio. In order to validate the bridge response following testing, the measured data are compared both with allowable limits existing in standards and with the results obtained using analytical or numerical models.In Romania, the dynamic testing of bridges is recommended by the current standards, only for important bridges, erected in complex or special solutions and also for large span bridges.The aim of this paper is to outline the results obtained from the on-site measurements during dynamic testing of a viaduct placed on the motorway A1, sector Orăştie-Sibiu. The bridge superstructure is a composite one, continuous girder on 12 spans: 40+10×60+40 m, the substructure consisting in 11 piers with lamellar elevations and variable height in the range 8.50-24m.In the paper a finite element model is also presented which was used for time-history analyses using an impulse type load. Finally, the results obtained on the site and using the numerical model are compared and discussed.</abstract>

Department of Strenth of Materials, Bridges and Tunnels

Dynamic Test of a Viaduct on the Orastie–Sibiu Highway

<abstract xmlns="http://www.w3.org/1999/xhtml">According to their size, aggregates are classified in coarse grained, fine grained, and fines. The determination of fines content in aggregate materials is very simple and is performed through the aggregate washing during the sieving procedure to define the gradation curve. The very fine material consists of grains having a size lower than 63 μm. The presence of fines directly influences the composition and performance of concrete and asphalt mixtures (e.g. asphalt content, elasticity, fracture). The strength and load carrying capacity of hot mix asphalt (HMA) results from the aggregate framework created through particle-particle contact and interlock. Fines or mineral filler have a role in HMA. The coarse aggregate framework is filled by the sand-sized material and finally by the mineral filler. At some point, the smallest particles lose contact becoming suspended in the binder not having the particle-particle contact that is created by the larger particles. The overall effect of mineral filler in hot mix asphalt specimens has been investigated through a series of laboratory tests. It is clear that a behaviour influenced by the adherence of fines to asphalt film has been developed. The optimum bitumen content requirement in case of stone filler is almost the same as that for fly ash. It has been found that the percentage of fly ash filler is crucial if it exceeds approximately a value of 4%.</abstract>

Significance of Fines in Hot Mix Asphalt Synthesis

<abstract xmlns="http://www.w3.org/1999/xhtml">A current worldwide economy problem includes both the responsible management of the planet's non-renewable resources and the waste management. The benefits of using recyclable materials and recycling technologies with asphalt mixtures consist mainly of reducing fuel consumption and greenhouse gas emissions. It is well known that oil (from which bitumen is obtained) is a non-renewable resource, hence the its price increase. Therefore, at present, the world is looking for solutions that will lead to a better use of natural resources and to an economic integration of sub-products from various industries. This paper intends to raise awareness of the possibilities for asphalt mixtures recycling and of the recyclable materials that can be used as additives with benefits of each.</abstract>

Considerations on the Benefits of Using Recyclable Materials for Road Construction

<abstract xmlns="http://www.w3.org/1999/xhtml">The judicious pavement design is the key factor in achieving the longest service life and the lowest maintenance and rehabilitation costs. It is based on the consideration of the phenomena in which the pavement structures are subjected to exploitation and the limitation of their destructive effects.The aim of this study is to verify the possibility of implementing in the flexible pavement structures design practice of another design criterion based on limiting the bituminous mixtures creep phenomenon and that to be called: <italic>The criterion of admissible octahedral shear stresses in the bituminous layers</italic>.Estimation of octahedral shear stresses is done with a calculation model based on finite element method, and hereafter referred to as <bold>2D ASFEM</bold> (<bold>2D A</bold>xi-<bold>S</bold>ymmetric <bold>F</bold>inite <bold>E</bold>lement <bold>M</bold>odel). The paper presents the results obtained by modeling several specific calculation assumptions for the behaviour of flexible pavement structures in service.The study underlines the fact that the <bold>O</bold>ctahedral <bold>S</bold>hear <bold>S</bold>tresses <bold>R</bold>atio (<bold>OSSR</bold>) can be an additional design criterion to be taken into account when designing flexible pavement structures alongside other established criteria.</abstract>

Department of Roads, Railways and Construction Materials

Flexible Pavement Design Criterion Based on Octahedral Shear Stresses

<abstract xmlns="http://www.w3.org/1999/xhtml">Analysis of the traffic safety factors in some region (road, section of road, road’s kilometer) is an important task in the field of traffic safety. It is necessary to constantly monitor, analyze, compare traffic safety situation in order to develop and improve measures for increasing the level of traffic safety. The first part of each analysis is finding of positions of traffic accidents and its casualties, in other words it is necessary to find its coordinates in the space-time coordinate system.This paper shows results of the descriptive statistical analysis of traffic accidents frequency on the rural road for the period 2005-2011. It will be point out advantages and disadvantages of this approach and also it will be suggested a new individual approach for determinate the mean time between consecutive traffic accidents.</abstract>

The Time-Space Approach in the Analysis of Traffic Safety on Rural Road

AHEAD OF PRINT

Volume 12 (2023): Issue 2 (December 2023)

Volume 12 (2023): Issue 1 (July 2023)

Volume 11 (2022): Issue 2 (December 2022)

Volume 11 (2022): Issue 1 (July 2022)

Volume 10 (2021): Issue 2 (December 2021)

Volume 10 (2021): Issue 1 (July 2021)

Volume 9 (2020): Issue 2 (December 2020)

Volume 9 (2020): Issue 1 (July 2020)

Volume 8 (2019): Issue 2 (December 2019)

Volume 8 (2019): Issue 1 (July 2019)

Volume 7 (2018): Issue 2 (December 2018)

Volume 7 (2018): Issue 1 (July 2018)

Volume 6 (2017): Issue 2 (December 2017)

Volume 6 (2017): Issue 1 (July 2017)

Volume 5 (2016): Issue 2 (December 2016)

Volume 5 (2016): Issue 1 (July 2016)

Volume 4 (2015): Issue 2 (December 2015)

Volume 4 (2015): Issue 1 (July 2015)

Volume 3 (2014): Issue 2 (December 2014)

Volume 3 (2014): Issue 1 (July 2014)

Volume 2 (2013): Issue 2 (December 2013)

Volume 2 (2013): Issue 1 (July 2013)

Volume 1 (2012): Issue 1 (December 2012)

Romanian Journal of Transport Infrastructure

Through its appearance (twice per year) magazine aims to be a high-quality scientific source of information for researchers, academics, engineers, practitioners, policy – makers, PhDs, students and anyone interested in various issues related to transport infrastructure: roads, bridges, railways and geotechnics.  The aim of the journal is to reflect the results of fundamental and applied research at a high level, maintained through a rigorous peer review performed by specialists, well known in the field, both at national and international level.  Romanian Journal of Transport Infrastructure (RJTI) involves the design, manufacture and maintenance of all categories of roads, airports, bridges, railways, tunnels and all types of transportation mean. The journal deals also with the materials and technologies in transport infrastructure and transportation engineering.  Welcome to receive original research papers involving latest discoveries and improvements in this area.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 