Hussein Aied | University College Dublin (original) (raw)
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Key Engineering Materials, 2013
The translational restraints associated to pin and rocker bearings are typically idealized in the... more The translational restraints associated to pin and rocker bearings are typically idealized in the form of fixed and free conditions. However, elastomeric bearings need to be represented with springs to reasonably predict the time- and frequency-domain response of bridges under traffic-induced vibrations. Therefore, changes in the response of these bearings are common as a result of aging, deterioration, variation in loading levels and/or environmental changes. The latter makes difficult to discern if changes in the frequency content of the structural response to ambient vibration are due to changes in temperature, changes in normal operational loads or the occurrence of damage. In this paper, the bridge is idealized by a beam model supported on a hysteretic translational sprung support. The purpose is twofold: (a) to gather a better understanding of the variations of the bridge response with bearing performance; and (b) to be able to quickly identify an anomaly in the bearing. Empir...
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Advances in Mechanical Engineering, 2015
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Moving load problems typically consider a structural material with properties that do not vary wh... more Moving load problems typically consider a structural material with properties that do not vary while the load traverses the structure. However, there is evidence that for some materials the structure will respond with a higher modulus of elasticity than that corresponding to a static test for sufficiently high strain rates. This paper investigates the variation in strain rate of a simply supported beam made of a viscoelastic material traversed by a moving load and its effect on the modulus of elasticity. The influence of speed and magnitude of the moving load on the displacement and strain responses of the beam is discussed.
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The use of an accurate modulus of elasticity when defining the mathematical model of a structure ... more The use of an accurate modulus of elasticity when defining the mathematical model of a structure is important to evaluate the true response to a load. In the case of moving loads, a constant ‘static’ modulus of elasticity has been typically employed. However, a moving load has a dynamic nature and it is able to generate a response in the underlying structure with significant changes in strain rate. Most of research agrees that the increase in loading rate and strain rate increases the ‘dynamic’ modulus, sometimes significantly with respect to a ‘static’ loading case. Factors that influence the magnitude of the increase include temperature, reinforcement, and type of concrete. In the case of a moving load, other parameters are the location of the section under investigation, and the velocity and magnitude of the load. This paper addresses the influence of these parameters on the mechanical characteristics of a concrete beam model when traversed by a load.
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The response of a simply supported Finite Element (FE) beam model is simulated under single movin... more The response of a simply supported Finite Element (FE) beam model is simulated under single moving load at different velocities. The beam is discretized into small elements and strain and displacement measurements are obtained at each time step. Contrary to previous work based on a constant modulus of elasticity, here the strain measurements use a time-variant (dynamic) modulus of elasticity. A time-variant modulus influences the bridge response, being more significant at highest velocities.
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A simply supported bridge is modelled to investigate the effect of a strain rate dependent modulu... more A simply supported bridge is modelled to investigate the effect of a strain rate dependent modulus of elasticity on the dynamic response of the structure to a moving load. The bridge is modelled as a one-dimensional discretized finite element beam and the moving load is represented by a point force. A constant modulus of elasticity is traditionally employed when simulating the dynamic response of structures under moving loads. In this paper, a time-variant modulus is used to calculate strains and displacements and compare them to the traditional approach for different speeds and bridge spans. The time-variant modulus is obtained from the strain rate of the structure which is used in turn to update the strain. The results show significant changes in the modulus and in the resulting load effect as load magnitude and speed increase.
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Bookmarks Related papers MentionsView impact
Key Engineering Materials, 2013
The translational restraints associated to pin and rocker bearings are typically idealized in the... more The translational restraints associated to pin and rocker bearings are typically idealized in the form of fixed and free conditions. However, elastomeric bearings need to be represented with springs to reasonably predict the time- and frequency-domain response of bridges under traffic-induced vibrations. Therefore, changes in the response of these bearings are common as a result of aging, deterioration, variation in loading levels and/or environmental changes. The latter makes difficult to discern if changes in the frequency content of the structural response to ambient vibration are due to changes in temperature, changes in normal operational loads or the occurrence of damage. In this paper, the bridge is idealized by a beam model supported on a hysteretic translational sprung support. The purpose is twofold: (a) to gather a better understanding of the variations of the bridge response with bearing performance; and (b) to be able to quickly identify an anomaly in the bearing. Empir...
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Advances in Mechanical Engineering, 2015
Bookmarks Related papers MentionsView impact
Moving load problems typically consider a structural material with properties that do not vary wh... more Moving load problems typically consider a structural material with properties that do not vary while the load traverses the structure. However, there is evidence that for some materials the structure will respond with a higher modulus of elasticity than that corresponding to a static test for sufficiently high strain rates. This paper investigates the variation in strain rate of a simply supported beam made of a viscoelastic material traversed by a moving load and its effect on the modulus of elasticity. The influence of speed and magnitude of the moving load on the displacement and strain responses of the beam is discussed.
Bookmarks Related papers MentionsView impact
The use of an accurate modulus of elasticity when defining the mathematical model of a structure ... more The use of an accurate modulus of elasticity when defining the mathematical model of a structure is important to evaluate the true response to a load. In the case of moving loads, a constant ‘static’ modulus of elasticity has been typically employed. However, a moving load has a dynamic nature and it is able to generate a response in the underlying structure with significant changes in strain rate. Most of research agrees that the increase in loading rate and strain rate increases the ‘dynamic’ modulus, sometimes significantly with respect to a ‘static’ loading case. Factors that influence the magnitude of the increase include temperature, reinforcement, and type of concrete. In the case of a moving load, other parameters are the location of the section under investigation, and the velocity and magnitude of the load. This paper addresses the influence of these parameters on the mechanical characteristics of a concrete beam model when traversed by a load.
Bookmarks Related papers MentionsView impact
The response of a simply supported Finite Element (FE) beam model is simulated under single movin... more The response of a simply supported Finite Element (FE) beam model is simulated under single moving load at different velocities. The beam is discretized into small elements and strain and displacement measurements are obtained at each time step. Contrary to previous work based on a constant modulus of elasticity, here the strain measurements use a time-variant (dynamic) modulus of elasticity. A time-variant modulus influences the bridge response, being more significant at highest velocities.
Bookmarks Related papers MentionsView impact
A simply supported bridge is modelled to investigate the effect of a strain rate dependent modulu... more A simply supported bridge is modelled to investigate the effect of a strain rate dependent modulus of elasticity on the dynamic response of the structure to a moving load. The bridge is modelled as a one-dimensional discretized finite element beam and the moving load is represented by a point force. A constant modulus of elasticity is traditionally employed when simulating the dynamic response of structures under moving loads. In this paper, a time-variant modulus is used to calculate strains and displacements and compare them to the traditional approach for different speeds and bridge spans. The time-variant modulus is obtained from the strain rate of the structure which is used in turn to update the strain. The results show significant changes in the modulus and in the resulting load effect as load magnitude and speed increase.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact