The implementation of road infrastructure projects often results in delays due to objective causes, with repercussions on the final execution deadline and with value implications. The use of critical path method for planning and the executin windows, will result in better time process management and optimization delays.
In this paper will be presented the influence of high temperatures on asphalt street pavement in terms of the influence of temperature on permanent deformations and thus the technical condition of the streets, comparable to the effects induced on extra-urban roads.
Environmental factors are one of the mayn factors being assaulted in operation and road structures are very important in terms of the influence they can have on the state road transport technical infrastructure.
Will be presented differences between urban road structures (streets) and extra-urban (road) both in terms of construction, the demands of traffic and environmental conditions to which they are subject.
Road structures extra-urban and urban areas are required differently in terms of the environmental conditions of the location ambient different thereof, that is, when the streets they are inside localities and the built environment significantly affect road infrastructure, unlike in the case of roads where they are located just outside the settlements, reducing the effect of air currents accumulation pavement surface temperature.
To demonstrate the influence of high temperatures on the pavement were conducted laboratory tests on asphalt mixtures in order to demonstrate the occurrence of reduction of physical characteristics, with adverse implications on the performance of applications similar to traffic.
Actually, the seismic movement has an irregular cyclic character.This can be equivalent to a determined number of uniform cyclical stresses equivalent in terms of effect.
Modeling the behavior of the soil to cyclical stress, is usually done, by establishing a relationship for primary loading like τ = f (γ) and after drawing the diagram “effortless strain curve”, in which τ is the stress, and γ is shear deformation. For modeling nonlinear behavior of the soil, we used like nonlinear models. The best known are the hyperbolic model and the Ramberg-Osgood model.
A missing piece in the design of bridge substructure is that the equation given in structural mechanics that assesses the axial forces in the piles of a deep foundation does not take into account the effect of lateral forces acting on the pile cap. In practice, pile forces are determined using a FEA software. This method, however, can not be easily incorporated into an automated program that performs local and global optimizations of a structure. One of the reasons is that this method is particularly demanding on the computational resources. Since a bridge can have a number of deep foundations, which must be verified for various combinations of actions, which need to be optimized, recalculated in various scenarios and then the entire process reiterated for all structural solutions, computational cost can become prohibitive. Another reason is that due to the lack of a relation between all the parameters and dimensions that influence the behaviour of a deep foundation, their optimization is difficult.
For this purpose, a parametric study has been carried out to investigate what parameters influence the relation between the lateral forces applied to the foundation and the axial forces that develop in the piles, and ultimately propose an equation that takes into account the lateral forces. The study is carried out using experimental data obtained on models using the finite element analysis method using SAP 2000 (v.15) software.
In Europe the need for local authorities to provide a high standard of living for their communities led to the establishment of the European noise mapping directive 2002/49/EC. Whilst Noise mapping itself doesn’t need continuous noise monitoring, states must produce a noise action plan which highlights actions they intend to take to reduce the number of people affected.
SUNET platform (System for Urban Noise and Eco-Traffic) was designed for improved management of the noise pollution in Cluj-Napoca and to provide up-to-date public data on a user-friendly interface. The implementation of the application over the entire municipality is highly advantageous for it creates a link between the town’s administration (the local authorities, the City Hall of Cluj-Napoca) and the user (the citizens) through this system which is dynamic, modern and compliant with the European regulations.
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.
Ghindea Cristian Lucian, Răcănel Ionuţ Radu and Cruciat Radu Iuliu
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.
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: The criterion of admissible octahedral shear stresses in the bituminous layers.
Estimation of octahedral shear stresses is done with a calculation model based on finite element method, and hereafter referred to as 2D ASFEM (2D Axi-Symmetric Finite Element Model). 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 Octahedral Shear Stresses Ratio (OSSR) can be an additional design criterion to be taken into account when designing flexible pavement structures alongside other established criteria.
Silviu Alexandru Constantinescu and Ionuț Radu Răcănel
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.
Elvira Kalaitzaki, George Kollaros and Antonia Athanasopoulou
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%.