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Amouzandeh A.,Vienna University of Technology | Zeiml M.,Vienna University of Technology | Zeiml M.,FCP Fritsch | Lackner R.,University of Innsbruck
Engineering Structures | Year: 2014

The development of measures to avoid or minimise the destructive effects of fires in tunnels requires a quantitative assessment of the thermal intake of the structure during such incidents. In the underlying work, a typical tunnel-fire scenario is analysed with the help of Computational Fluid Dynamics (CFD) in order to predict temperature distributions inside the tunnel which in turn shall be used to assess the structural stability of the concrete lining. The CFD simulations are based on a fire code previously developed within the framework of OpenFOAM. The fire is simulated in an arched single-track, an arched double-track and a rectangular double-track cross-section of real dimensions taking into account two different ventilation velocities (0.5 and 3. m/s). Results are compared in terms of temperature distributions within the cross-section and longitudinal temperature distributions at ceiling level. Except for the temperature distribution within the cross-sections, little difference in results is seen for the two double-track tunnels with the low ventilation velocity (0.5. m/s), whereas higher temperature levels and a faster downstream movement of hot gases are observed in the single-track tunnel. For the high ventilation velocity (3. m/s), temperature levels drop dramatically and flow parameters within the three tunnel cross-sections differ insignificantly. In addition, a comparison of temperature profiles inside the concrete tunnel lining with results of a more detailed 1D calculation is presented. In order to obtain the most accurate temperature profiles, a procedure is suggested, where the 1D heat-conduction equation is solved by using the fluid temperatures from a previous CFD simulation, taking into account the temperature dependency of thermo-physical parameters of concrete and, if necessary, the risk of spalling. © 2014 Elsevier Ltd.


Zhang Y.,Vienna University of Technology | Zeiml M.,FCP Fritsch | Pichler C.,University of Innsbruck | Lackner R.,University of Innsbruck | Mang H.A.,Vienna University of Technology
Poromechanics V - Proceedings of the 5th Biot Conference on Poromechanics | Year: 2013

During spalling of fire-loaded concrete, the cross-sectional area of the concrete member is reduced, seriously affecting the integrity of the structure. Spalling is mainly attributed to two types of processes: thermo-hygral and thermo-mechanical. Thermo-hygral processes refer to the build-up of vapor pressure inside the concrete pores. Thermo-mechanical processes refer to the thermally-induced, restrained deformation of concrete. Both types of processes are closely connected to the physical and chemical behavior of concrete as a porous material. This contribution aims at realistic simulation of the stress state within fire-loaded concrete in order to attain insight into the development and occurrence of the critical state right before and during the event of spalling. This requires modeling of the two above-mentioned types of processes via a coupled thermo-hygro-chemo-mechanical model. Based on a coupled thermo-hygro-chemical model, the authors adopted a formulation of the effective-stress theory by combining the respective model with a multiscale homogenization approach (with the latter considering dehydration as the reverse of hydration), which gave access to the Biot's coefficent as a function of temperature. This led to a coupled thermo-hygro-chemo-mechanical code simulating the stress state in fire-loaded concrete as a consequence of both thermo-hygral and thermo-mechanical processes. In this coupled code, an embedded strong-discontinuity model is to be implemented, which is capable of capturing and tracking the propagation of a crack evolving in concrete as a quasi-brittle material. The aim is to attain the crack path as well as the width of the crack with the latter being closely connected to permeation of gas and water through the crack. With the resulting coupled model, it will be possible to take into account all major couplings, allowing to realistically simulate the spalling process. © 2013 American Society of Civil Engineers.


Zeiml M.,FCP Fritsch | Zeiml M.,University of Innsbruck | Zhang Y.,Vienna University of Technology | Pichler C.,University of Innsbruck | And 2 more authors.
MATEC Web of Conferences | Year: 2013

The presented research work contributes to the realistic simulation of the stress state within fire-loaded concrete in order to attain insight into the development and occurrence of the critical state right before and during the event of spalling. A coupled thermo-hygro-chemo-mechanical code simulating the stress state as a consequence of both thermo-hygral and thermo-mechanical processes is presented together with an embedded strong-discontinuity model which is capable of capturing and tracking the propagation of a crack evolving in concrete as a quasi-brittle material. Combination of the two mentioned models is currently under way. With the resulting coupled model, it will be possible to take into account all major couplings, allowing to realistically simulate the spalling process. © Owned by the authors, published by EDP Sciences, 2013.


Zhang Y.,Vienna University of Technology | Pichler C.,University of Innsbruck | Yuan Y.,Tongji University | Zeiml M.,Vienna University of Technology | And 2 more authors.
Engineering Structures | Year: 2013

In the process of hydration of concrete, there are considerable interacting physical and chemical changes inside the material, affecting both composition and morphology of concrete at early ages. These changes are properly considered within multiscale models comprising several scales of observation and giving access to the effective properties via upscaling. In this paper, a multiscale model for early-age concrete is implemented into a multifield (thermo-hygro-chemo-mechanical) framework, which accounts for all major processes among the solid, liquid, and gas phases of concrete by means of mass, energy, and momentum equilibrium. The proposed modeling approach is employed for the investigation of the effect of formwork removal (stripping) of early-age concrete, exposing the concrete surface to the outside environment which may cause early-age cracking of concrete structures. Based on the multiscale approach, the authors evaluate the cracking risk of concrete members with respect to the underlying mix-design, size of the concrete member, and stripping time, providing first insight into the influence of these parameters on the cracking risk of early-age concrete. © 2012 Elsevier Ltd.


Grant
Agency: Cordis | Branch: H2020 | Program: Shift2Rail-RIA | Phase: S2R-CFM-IP3-02-2016 | Award Amount: 7.29M | Year: 2016

IN2SMART represents the 1st proposal of the Shift2Rail members referred, according to MAAP, to the following Technology Demonstrators (TDs): TD3.7 Railway Information Measuring and Monitoring System (RIMMS), TD3.6 Dynamic Railway Information Management System (DRIMS) and TD3.8 Intelligent Asset Management Strategies (IAMS). These TDs will deploy an overall concept for Intelligent Asset Management based on the following three main interlinked layers: Measuring and Monitoring systems to collect data from the field related to the railway assets status: IN2SMART will develop unmanned systems for remote monitoring; track geometry, switches & crossings and signalling monitoring systems; innovative measurement of train parameters and wheel defects combined with rolling stock identifications systems. Data management, data mining and data analytics procedures to process data from the field and from other sources: IN2SMART will develop standard open interfaces to access heterogeneous maintenance-related data; analytic tools to automatic detect anomalies, discover and describe maintenance workflow processes and predict railway assets decay towards prescriptive maintenance. Degradation models and decision making tools to support maintenance strategies and execution: IN2SMART will lay the foundation of a generic framework for asset management and decision support process. This framework will specify the scope, objectives, workflow and outcomes of the decision-making process for maintenance interventions planning, and will be the enabler for the development of future decision support tools and systems. IN2SMART will also develop an optimised tamping tool and a robot platform for maintenance works. IN2SMART will complement the work of the IN2RAIL lighthouse project to reach a homogeneous TRL4/5 demonstrator. The following Grant will start from IN2SMART to reach the final Integrated Technology Demonstrators that will deploy the overall concept of Intelligent Asset Management.


Strauss A.,University of Natural Resources and Life Sciences, Vienna | Karimi S.,University of Natural Resources and Life Sciences, Vienna | Kopf F.,FCP Fritsch | Capraru C.,FCP Fritsch | Bergmeister K.,University of Natural Resources and Life Sciences, Vienna
Structural Concrete | Year: 2015

For today's railways, the continuous welded rail, which enhances driving dynamics and comfort for passengers, is often the construction method of choice. However, bridges and viaducts, which can be seen as singularities in the railway substructure, still pose a few unsolved problems; the bridge structure deforms under the impacts of thermal variation, creep, shrinkage, train passage and braking. The track-bridge interaction is an important parameter in railway bridge design. Measurement campaigns and research projects have been performed to investigate the interaction process and learn how to predict longitudinal forces in the rail and the concrete slab track. For the construction of long bridges on high-speed railway lines, new computational tools, monitoring systems and enhanced verification methods for tolerable rail stresses on bridges had to be developed. In order to take the modified stiffness conditions and recent findings on rail resistance into account, the verification schemes and safety concepts based on monitoring data have to be revised and performance-based methods need to be developed. The target of this article is to present monitoring- and reliability-based assessment methods for the concrete structure-rail interaction using monitoring and non-linear analysis techniques. Copyright © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.


Apostolidi E.,University of Natural Resources and Life Sciences, Vienna | Bergmeister K.,University of Natural Resources and Life Sciences, Vienna | Hilber R.,University of Natural Resources and Life Sciences, Vienna | Strauss A.,University of Natural Resources and Life Sciences, Vienna | And 5 more authors.
Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014 | Year: 2015

The current European road network and concrete bridges in particular have suffered in the past few decades serious and increasing damages, due to e.g. insufficient maintenance, incorrect calculation assumptions, change in use, constructional mistakes, environmental influences, etc. As engineering structures are designed in planning and execution according to current regulations and state of the art, the maintenance of such structures constitutes a serious problem for engineers. Although the addition of new reinforced concrete layers is a common practice to increase the shear capacity of a structural element, the objective of the paper is the development, optimization and assessment of an innovative steel reinforcement in form of sheet, replacing common reinforcing bars. A preliminary investigation considering the material and geometrical parameters of such a reinforcement type is presented, through a series of numerical simulations and experimental tests. © 2015 Taylor & Francis Group, London.


Pistrol J.,Vienna University of Technology | Adam D.,Vienna University of Technology | Villwock S.,HA MM AG | Volkel W.,HA MM AG | Kopf F.,FCP Fritsch
Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015 | Year: 2015

Dynamic roller compaction has become the common method for near-surface compaction, because dynamic rollers are much more efficient compared to static rollers. Two types of excitation are mainly used for dynamic roller compaction, the vibratory and the oscillatory roller. In the presented study the differences in functioning, mode of operation and loading the soil are outlined for the two types of excitation. First results of large-scale in-situ tests are presented in which the vertical earth pressure and tri-axial accelerations have been measured. Moreover a new indicator for the evaluation of the slip between the surface of an oscillatory drum and soil is presented. © The authors and ICE Publishing: All rights reserved, 2015.


Pistrol J.,Vienna University of Technology | Villwock S.,HAMM AG | Volkel W.,HAMM AG | Kopf F.,FCP Fritsch | Adam D.,Vienna University of Technology
Procedia Engineering | Year: 2016

CCC systems are the state of the art method for an assessment of the achieved compaction success with vibratory rollers. However, CCC systems were not available for oscillatory rollers, which differ from vibratory rollers not only in their construction, but also in their motion behaviour and way of dynamically loading the soil. Experimental field tests were performed to analyse the motion behaviour of an oscillatory drum and a CCC value for oscillating rollers is presented based on empirical observations and a semi-analytical modelling of the drum-soil interaction. Moreover, the algorithm of the CCC value is tested on measurement data of the experimental field tests and the influence of weak spots on the CCC values is investigated. © 2016 The Authors. Published by Elsevier B.V.


Kopf F.,FCP Fritsch | Schafer D.,ZT GmbH | Pistrol J.,Vienna University of Technology
Research and Applications in Structural Engineering, Mechanics and Computation - Proceedings of the 5th International Conference on Structural Engineering, Mechanics and Computation, SEMC 2013 | Year: 2013

In common buildings the Soil-Structure-Interaction (SSI) is governed by the elastic behavior of the building. The best conditions to see the soil effect predominate would be a dynamic rigid body movement of a massive building. For this reason measurements were carried out on an old anti-aircraft tower from World War II on typical Viennese soil conditions. The dynamic properties of the soil could be determined in two different ways. The first one is the common way using the dispersion of the Rayleigh waves on the soil surface and the back calculation to shear wave profiles. The second approach is the back calculation of the soil stiffness based on the soil-structure-interaction. With the simultaneous measurement of the dynamic movement of the building the kinematic behavior of the SSI could be determined. The tilting oscillations of the tower in both directions with different frequencies transmitted to the soil could be measured in the surroundings. The decay of these vibrations and their influence on the H/V-method results was studied. The results of the dynamic measurements were compared with different methods of numerical simulation. The benefits and the disadvantages of the methods can be compared. The calculation values of the numerical models could be calibrated with the real dynamic properties of the measured SSI-system. © 2013 Taylor & Francis Group.

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