| 1. |
- Arvidsson, Therese, et al.
(författare)
-
Influence of Sleeper Passing Frequency on Short Span Bridges : Validation against Measured Results
- 2017
-
Konferensbidrag (refereegranskat)abstract
- The railway track, being discretely supported at each sleeper, has a varying stiffness. The periodic loading from the wheels passing the sleepers at a certain speed introduces the sleeper passing frequency. This excitation of the track is a well-known source of vibration for track embankments. However, the interaction between the sleeper passing frequency and the railway bridge vibration is not well studied. In this paper, a 2D finite element model is calibrated against measured frequency response functions from a short span portal frame bridge. The track is modelled with the rail as a beam resting on discrete spring–dashpots at each sleeper location. In replicating the measured signals from train passages, the train load is typically idealized as moving forces. For the case study bridge, the resulting bridge deck acceleration amplitudes from such a moving force analysis were significantly lower compared to the measured signal. It is shown that if the wheel mass is introduced in the model, and thus the sleeper passing frequency, the model provides results in good agreement with measured data. Thus, it is demonstrated that the bridge deck vibration can be greatly amplified if the sleeper passing frequency matches a bridge frequency. A sensitivity analysis shows that the effect of the sleeper passing frequency is sensitive to track stiffness and bridge frequency.
|
|
| 2. |
- Hosseini Tehrani, Seyed Amin, et al.
(författare)
-
Dynamic soil-structure interaction of a continuous railway bridge
- 2024
-
Ingår i: Eurodyn 2023. - : IOP Publishing. ; , s. 102007-
-
Konferensbidrag (refereegranskat)abstract
- This paper presents an efficient 2D beam model of a continuous single-trackconcrete slab bridge considering the effect of surrounding soil conditions at the location ofthe retaining walls. A 3D model is used to investigate the backfill soil’s added flexibility fordifferent soil properties. It is shown that for the first bending mode, the additional dynamicstiffness of the backfill soil can be modeled using equivalent vertical and rotational springs.Various experimental tests have been performed on the studied railway bridge, including forcedvibration tests and train passage loadings. Good agreement is found between the 2D model andthe experimental data. It is shown that removing the soil causes both a shift in the structure’snatural frequencies (and their corresponding resonant speed) and a substantial increase inacceleration amplitude. This may give the impression that the bridge is not suitable for highspeedtrain passage. It is also shown that the bridge’s response to train passage is mainlygoverned by the first bending mode.
|
|
| 3. |
- Silva, Artur, et al.
(författare)
-
New Contributions for Damping Assessment on Filler-Beam Railway Bridges Framed on In2Track EU Projects
- 2023
-
Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 13:4
-
Tidskriftsartikel (refereegranskat)abstract
- Structural damping is an important characteristic in railway bridges, which affects the performance of the structure, especially for bridges with train speeds higher than 200 km/h. The accurate evaluation of damping must be performed properly to correctly assess the structural performance of the bridge under dynamic loading conditions. The present article introduces an alternative methodology that contributes to the assessment of damping coefficients with application to railway bridges. The methodology is based in the Prony method with an energy-sorting technique for the identification of dominant frequencies of a free vibration signal of a passing train. The numerical validation of the method is based on a sensitivity analysis of the free vibration periods of signals through the evaluation of influence lines of displacement and numerically simulated receptance tests, and in the estimation of the damping coefficient from the free vibration period obtained in a train-bridge interaction dynamic analysis with a known imposed value. Finally, and in the scope of the In2Track2 and In2Track3 projects, the experimental assessment of damping coefficients using this methodology was carried out, considering four filler-beam bridges from the Portuguese Railway Network. The ambient vibration tests allowed the evaluation of the main frequencies and damping in these bridges, and the dynamic tests under railway traffic allowed the definition of the dynamic response of these bridges and subsequent application of the Prony method for two types of trains. The results of this work allow a new update of the database for damping coefficients of filler-beam railway bridges, contributing to future revisions of EN1991-2.
|
|
| 4. |
- Tehrani, Seyed Amin Hosseini, et al.
(författare)
-
Dynamic soil–structure interaction of a three-span railway bridge subject to high-speed train passage
- 2024
-
Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 301
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, the influence of Soil-Structure Interaction (SSI) on the dynamic behavior of a three-span concrete slab railway bridge with integrated retaining walls is investigated. The bridge is subjected to controlled excitations using a hydraulic actuator with different frequencies and load amplitudes. A 3D model of the railway bridge-soil system is implemented and calibrated using the experimental frequency response functions at each sensor location. A soil-free model is also created to compare with the calibrated model. It is observed that the dynamic behavior of the railway bridge is substantially altered by the presence of the surrounding soils, and neglecting SSI can lead to underestimation and inaccurate results. Additionally, the calibrated model is used for further train-passage analyses. For the studied bridge, neglecting SSI increases the maximum acceleration response of the bridge during high-speed train passages from 5.5 m/s2 up to 14.5 m/s2. It is also shown that the response of the bridge during train passage is predominantly influenced by its first bending mode, with higher modes inducing no discernible effect. Finally, parametric studies are performed in order to study the uncertainties related to the soil properties.
|
|
| 5. |
- Zangeneh, Abbas, et al.
(författare)
-
Dynamic soil-structure interaction in resonant railway bridges with integral abutments
- 2020
-
Ingår i: Proceedings of the International Conference on Structural Dynamic , EURODYN. - : European Association for Structural Dynamics. ; , s. 1625-1633
-
Konferensbidrag (refereegranskat)abstract
- In this work, the effect of the surrounding soil condition on the fundamental modal characteristics and dynamic response of railway bridges with integral abutments is studied. Due to the computational cost of the full FE models and the lack of reliable simplified models, the effect of the soil-structure interaction is usually neglected in the vibration analysis of the high-speed railway bridges. In the present study, an efficient simplified numerical model is employed to evaluate the modal characteristics of the railway bridge-soil systems. After verifying the accuracy of the simplified numerical model against rigorous models, the effect of the span length and abutment/soil stiffness on the dynamic response of the studied bridges is investigated through a comprehensive parametric study. Several case studies which covers different span lengths and abutment conditions are chosen. It is shown that the SSI has substantial effect on the dynamic response of the short and stiff bridges while its effect decreases as the ratio between the deck stiffness and the abutment/soil stiffness decreases. The results may lead to review the recommended modal damping ratios for this type of bridges in the code provisions and design manuals.
|
|
| 6. |
- Zangeneh, Abbas, 1980-, et al.
(författare)
-
Fundamental Modal Properties of Simply Supported Railway Bridges Considering Soil-Structure Interaction Effects
- 2019
-
Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier. - 0267-7261 .- 1879-341X. ; 121, s. 212-218
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a simplified discrete model for calculating the modal parameters of the fundamental vertical mode of a simple beam on viscoelastic supports is proposed. Exact closed-form expressions for the fundamental natural frequency and modal damping ratio of the aforementioned coupled system are derived, as a function of the beam geometry and the foundation impedances. Using this model, the effect of the dynamic stiffness and dissipation capacity of the foundation-soil system on the modal characteristics of the fundamental vertical mode of the railway beam bridges is investigated and discussed. The proposed closed-form expressions, in combination with the impedance functions of different foundation-soil systems, can clarify the main features of dynamic SSI analysis of the railway beam bridges and lead to review the recommended modal damping ratios in the code provisions and design manuals.
|
|
| 7. |
- Zangeneh, Abbas, et al.
(författare)
-
Identification of soil-structure interaction effect in a portal frame railway bridge through full-scale dynamic testing
- 2018
-
Ingår i: Engineering structures. - : ELSEVIER SCI LTD. - 0141-0296 .- 1873-7323. ; 159, s. 299-309
-
Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to identify the effect of soil-structure interaction on the dynamic response of,a portal frame railway bridge. The study aims to validate the accuracy of numerical models in evaluating the dynamic stiffness and modal properties of the bridge-soil system. To achieve this aim, a controlled vibration test has been performed on a full-scale portal frame bridge to determine the modal properties of the system through measuring Frequency Response Functions. The results of the dynamic test provide reference data for FE model calibration as well as valuable information about the dynamic behavior of this type of bridges. Using the experimental data, an FRF-based model updating procedure was used to calibrate a full 3D solid model involving the entire bridge track-soil system. Both measured and computed responses identify the substantial contribution of the surrounding soil on the global damping of the system and highlight the importance of the soil-structure interaction on the dynamic response of this type of bridges. The identified modal damping ratio corresponding to the fundamental bending mode of the studied bridge was nearly 5 times higher than the recommended design values. A simplified model for the surrounding soil was also proposed in order to attain a less complicated model appropriate for practical design purposes.
|
|
| 8. |
- Zangeneh, Abbas, 1980-, et al.
(författare)
-
Modal analysis of coupled soil-structure systems
- 2021
-
Ingår i: Soil Dynamics and Earthquake Engineering. - : Elsevier BV. - 0267-7261 .- 1879-341X. ; 144
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an efficient approach for the modal analysis of coupled soil-structure systems, for which the dynamic response is strongly influenced by the embedment in the soil. The methodology is based on a finite element-perfectly matched layer model that allows for the derivation of frequency-independent system matrices and the computation of the modal properties of the coupled system. This is achieved by solving a nonlinear eigenproblem using a Compact Rational Krylov (CoRK) eigensolver. A procedure is developed to sort the computed eigenpairs, filter out the spurious modes of the system which are related to the near-field and truncated far-field soil subdomains and select the physical structural modes of system. The proposed method can be used in the dynamic assessment and structural identification of strongly coupled soil-structure systems such as fully or partially buried structures and allows for the interpretation of experimentally identified modal properties of these systems, especially in the presence of highly damped or closely spaced coupled modes. The applicability and the scalability of the proposed approach for 2D and 3D problems is demonstrated in two case studies.
|
|
| 9. |
- Zangeneh Kamali, Abbas, 1980-
(författare)
-
Dynamic Soil-Structure Interaction Analysis of High-Speed Railway Bridges : Efficient modeling techniques and Experimental testing
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work reported in this thesis presents a general overview of the resonant response of high-speed railway bridges considering soil-structure interaction. The study aims to identify the effect of the surrounding and underlying soil on the global stiffness and damping of the structural system. This may lead to better assumptions and more efficient numerical models for design. A simple and accurate analytical model for computing the dynamic characteristics of the fundamental bending mode of single span beam bridges on viscoelastic supports was proposed. This model was used to study the effect of the dynamic stiffness of the foundation on the modal parameters of railway beam bridges. It was shown that the variation in the underlying soil profiles leads to a different dynamic response of the system. This effect depends on the ratio between the flexural stiffness of the bridge and the dynamic stiffness of the foundation-soil system but also on the ratio between the resonant frequency of the soil layer and the fundamental frequency of the bridge. In addition, an approximate formula to estimate maximum resonant acceleration of beams under passage of high-speed trains has been proposed.The effect of the surrounding soil conditions on the vertical dynamic response of portal frame bridges was also investigated both numerically and experimentally. To this end, different numerical models have been developed. A simplified and accurate model for the surrounding soil was also proposed in order to define a less complicated approach appropriate for practical design purposes. Controlled vibration tests have been performed on six full-scale portal frame bridges to determine the modal properties of the bridge-soil system and calibrate the numerical models. Both experimental and numerical results identified the substantial contribution of the surrounding soil on the global damping of short-span portal frame bridges while the effect decreases as the ratio between the deck stiffness and the abutment/soil stiffness decreases.
|
|
| 10. |
- Zangeneh Kamali, Abbas, 1980-
(författare)
-
Dynamic Soil-Structure Interaction Analysis of Railway Bridges : Numerical and Experimental Results
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work reported in this thesis presents a general overview of the dynamic response of short-span railway bridges considering soil-structure interaction. The study aims to identify the effect of the surrounding and underlying soil on the global stiffness and damping of the structural system. This may lead to better assumptions and more efficient numerical models for design.A simple discrete model for calculating the dynamic characteristics of the fundamental bending mode of single span beam bridges on viscoelastic supports was proposed. This model was used to study the effect of the dynamic stiffness of the foundation on the modal parameters (e.g. natural frequency and damping ratio) of railway beam bridges. It was shown that the variation in the underlying soil profiles leads to a different dynamic response of the system. This effect depends on the ratio between the flexural stiffness of the bridge and the dynamic stiffness of the foundation-soil system but also on the ratio between the resonant frequency of the soil layer and the fundamental frequency of the bridge.The effect of the surrounding soil conditions on the vertical dynamic response of portal frame bridges was also investigated both numerically and experimentally. To this end, different numerical models (i.e. full FE models and coupled FE-BE models) have been developed. Controlled vibration tests have been performed on two full-scale portal frame bridges to determine the modal properties of the bridge-soil system and calibrate the numerical models. Both experimental and numerical results identified the substantial contribution of the surrounding soil on the global damping of short-span portal frame bridges. A simplified model for the surrounding soil was also proposed in order to define a less complicated model appropriate for practical design purposes.
|
|
