The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
Said Jalali - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on the mechanical behaviour of the fiber reinforced high performance Concrete Tunnel segment
Composite Structures, 2011Co-Authors: Yining Ding, Hekai Liu, F Pachecotorgal, Said JalaliAbstract:The main objective of this paper is to investigate the composite effect of macro steel fiber and steel rebar on the mechanical behaviour of Tunnel segment with fiber reinforced high-performance Concrete (FRHPC). A new experimental method is used for simulating the loading state of the Tunnel segment. The experiment including several symmetric-inclination beams with various steel ratios and fiber contents has been carried out. The results indicate that the addition of 50 kg/m 3 steel fibers can partly replace the shear reinforcement, and increases the ultimate load and the energy absorption capacity as well as the toughness. The combination of steel fibers and steel rebars illustrates synergistic response and indicates an optimal choice of reinforcement for Tunnel segment.
L Daloia - One of the best experts on this subject based on the ideXlab platform.
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effect of fibres on early age cracking of Concrete Tunnel lining part ii numerical simulations
Tunnelling and Underground Space Technology, 2016Co-Authors: Matthieu Iffau, Farid Enboudjema, L DaloiaAbstract:Abstract The early-age cracking of Concrete structures increases permeability and diffusivity and moreover accelerates the penetration of liquid, gas and aggressive agents. Consequently, the serviceability of these structures could be reduced drastically. Early-age cracking might be due to external loading, but also to the internal or external restraint resulting from autogenous, drying and thermal shrinkage. This study focuses more specifically on these latter phenomena. In the first part of this study (see effect of fibres on early-age cracking of Concrete Tunnel lining - Part I: Laboratory testing), ring tests were performed to investigate the sensitivity of Concrete to cracking due to both shrinkage strain and type of fibre (two organic fibres and one steel fibre were studied). Ring test results were then used to validate the capacity of a chemo-thermo-viscoelastic damage model aimed at reproducing the complex behaviour of fibre-reinforced Concrete subjected to restrained shrinkage through identifying the material parameters with standardised tests. The numerical simulations conducted on a real Tunnel lining show that for the studied geometries and Concrete mixtures, thermal shrinkage constitutes the major phenomenon capable of causing early-age transverse cracks and moreover crack opening is highly dependent on the type of reinforcement. Modifications to both fibre type and lining thickness may serve to avoid the onset of transverse cracks.
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effect of fibres on early age cracking of Concrete Tunnel lining part i laboratory ring test
Tunnelling and Underground Space Technology, 2016Co-Authors: Matthieu Iffau, Farid Enboudjema, L DaloiaAbstract:Abstract The cracking of Concrete structures can drastically reduce their serviceability, specifically by inducing a decrease in bearing capacity while their permeability and diffusivity are being increased. Cracking therefore leads to a faster penetration of liquid, gaseous and aggressive agents, which may reduce the durability and the tightness of the structures. It may be caused by an external loading or else by the self- or external restraint of autogenous, drying and thermal shrinkage. This paper will focus on the latter of these phenomena. In the first part of this study (part I: Laboratory test), ring tests are performed to investigate the sensitivity of Concrete to cracking due to both shrinkage strain and fibre type (two organic fibres and one steel fibre have been studied). Results obtained show that the use of polypropylene microfibres does not delay the age at which the first crack appears but does slightly reduce crack opening. Polypropylene and steel macrofibres have a greater effect since cracking is delayed and the crack opening is significantly reduced. Tensile strength results indicate that a portion of the cracking delay may be attributed to the tensile strength increase resulting from fibre reinforcement.
Z Rinaldi - One of the best experts on this subject based on the ideXlab platform.
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precast Concrete Tunnel segments with gfrp reinforcement
Journal of Composites for Construction, 2017Co-Authors: Simone Spagnuolo, Alberto Meda, Z Rinaldi, Antonio NanniAbstract:AbstractThe possibility of substituting traditional steel reinforcement with glass fiber–reinforced polymer (GFRP) bars in precast Concrete Tunnel segmental linings is investigated. The use of GFRP...
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design according to mc2010 of a fibre reinforced Concrete Tunnel in monte lirio panama
Structural Concrete, 2012Co-Authors: Angelo Caratelli, Alberto Meda, Z RinaldiAbstract:This paper discusses the possibility of using precast Tunnel segments in fibre-reinforced Concrete without traditional reinforcement. The case study of a hydraulic Tunnel in Monte Lirio, Panama, excavated with a Tunnel boring machine (TBM) by SELI S.p.A., has been analysed. The segments were designed according to the draft of Model Code 2010. In order to achieve the required performance and to optimize the structural behaviour, three different types of steel fibre were considered in the research. The design was backed up by full-scale tests on precast segments. In particular, 18 full-scale tests were performed, including point load tests simulating the thrust of the TBM and bending tests. The results show the good behaviour of the elements and indicate the fibre-reinforced Concrete suitable for the precast elements.
Claus Germann Petersen - One of the best experts on this subject based on the ideXlab platform.
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rapid and economical evaluation of Concrete Tunnel linings with impulse response and impulse radar non destructive methods
Ndt & E International, 2005Co-Authors: Allen G Davis, Claus Germann PetersenAbstract:Concrete Tunnel linings, whether pre-cast or cast in place, are designed to distribute external soil pressures as uniformly as possible through the Tunnel shell. To this effect, the contact between the lining and the surrounding soil is usually assured by grouting the annular space between. Any voiding in the grout at this interface negates the purpose of the grout. This paper describes the use of non-destructive testing to examine the efficiency of Tunnel lining grouting programmes, with particular emphasis on results obtained by the impulse response and impulse radar methods. The rail, water supply and sewer Tunnels discussed in this article vary in diameter between 1 and 5 m, and emphasis is placed on the rapid results obtained by these methods.
Ki Yong A - One of the best experts on this subject based on the ideXlab platform.
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probabilistic assessment to predict the time to corrosion of steel in reinforced Concrete Tunnel box exposed to sea water
Construction and Building Materials, 2009Co-Authors: Hawo Song, Seungwoo Pack, Ki Yong AAbstract:Abstract This study concerned the service life prediction, in terms of chloride-induced steel corrosion, of a Concrete Tunnel-box structure placed on seabed. To calculate the time to steel corrosion, the rate of chloride transport in the identical Concrete mix to the structure was tested, and the chloride threshold level for corrosion was assumed by a literature review from 65 published data. Then, the Monte Carlo Simulation was used to calculate the probability of steel corrosion and its corresponding service life, assuming that the corrosion initiates at 10% of the probability of corrosion. As a result, the service life depended on the time dependency of chloride transport. The service life was equated to 31, 51, 85, and 147 years, at 0.1, 0.2, 0.3 and 0.4 of the age factors, respectively, while the time independent model indicated only 27 years of the service life. Finally, methods to raise the service life were discussed.