Full-Scale Forced Vibration Tests of a Railway
Bridge
Andreas Andersson (B)
Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden
adde@kth.se
Abstract. This paper presents results from experimental testing of a railway
bridge. Forced vibration tests was performed using a hydraulic actuator with variable load amplitude. The estimated modal properties show that the increased load
amplitude results in lower natural frequency and higher damping, especially for
the first mode of vibration. Despite this, even at relatively large amplitude of vibration the estimated damping is lower than proposed by Eurocode EN 1991–2. A
simple 2D model is presented that shows good agreement with the experimental
results, both regarding natural frequencies, mode shapes and the response from
passing trains.
Keywords: Railway bridge · Dynamic · Forced vibration test · Damping ·
Resonance
1 Introduction
Railway bridges may experience large vibrations from passing trains if the load frequency
of the train coincides with the natural frequency of the bridge. For slender bridges on
high-speed lines this may occur within the range of the operational speed. In combination
with low inherent damping of the bridge, excessive vibrations during train passage may
pose both a safety risk and riding comfort problems.
When assessing the dynamic performance of a bridge it is vital to have accurate
estimates of the dynamic characteristics, something that is often difficult to assess prior
to testing the bridge. Values for modal damping is often taken from design codes, e.g.
EN 1991–2, which are based on lower bound estimates of experimental testing. Most
of these experimental tests are however based on free vibrations after train passages,
typically at much lower amplitudes of vibration than the design limits. Due to different
nonlinear effects, the response may change at higher amplitudes of vibration, potentially
resulting in increased damping.
In this paper full-scale experimental testing of an existing railway bridge is presented.
Forces vibration tests are performed using a hydraulic actuator that enables the study of
relatively high amplitude of vibrations at resonance.
The case study bridge is part of the Bothnia Line in Sweden, located about 500 km
North of Stockholm. It is a single track bridge and the allowable train speed is 250 km/h.
A photo of the bridge is shown in Fig. 1, during passage of an X62 passenger train.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 224–232, 2021.
https://doi.org/10.1007/978-3-030-64690-5_21
Bridge
Andreas Andersson (B)
Royal Institute of Technology, Brinellvägen 23, 100 44 Stockholm, Sweden
adde@kth.se
Abstract. This paper presents results from experimental testing of a railway
bridge. Forced vibration tests was performed using a hydraulic actuator with variable load amplitude. The estimated modal properties show that the increased load
amplitude results in lower natural frequency and higher damping, especially for
the first mode of vibration. Despite this, even at relatively large amplitude of vibration the estimated damping is lower than proposed by Eurocode EN 1991–2. A
simple 2D model is presented that shows good agreement with the experimental
results, both regarding natural frequencies, mode shapes and the response from
passing trains.
Keywords: Railway bridge · Dynamic · Forced vibration test · Damping ·
Resonance
1 Introduction
Railway bridges may experience large vibrations from passing trains if the load frequency
of the train coincides with the natural frequency of the bridge. For slender bridges on
high-speed lines this may occur within the range of the operational speed. In combination
with low inherent damping of the bridge, excessive vibrations during train passage may
pose both a safety risk and riding comfort problems.
When assessing the dynamic performance of a bridge it is vital to have accurate
estimates of the dynamic characteristics, something that is often difficult to assess prior
to testing the bridge. Values for modal damping is often taken from design codes, e.g.
EN 1991–2, which are based on lower bound estimates of experimental testing. Most
of these experimental tests are however based on free vibrations after train passages,
typically at much lower amplitudes of vibration than the design limits. Due to different
nonlinear effects, the response may change at higher amplitudes of vibration, potentially
resulting in increased damping.
In this paper full-scale experimental testing of an existing railway bridge is presented.
Forces vibration tests are performed using a hydraulic actuator that enables the study of
relatively high amplitude of vibrations at resonance.
The case study bridge is part of the Bothnia Line in Sweden, located about 500 km
North of Stockholm. It is a single track bridge and the allowable train speed is 250 km/h.
A photo of the bridge is shown in Fig. 1, during passage of an X62 passenger train.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. N. Atluri and I. Vušanovi´ c (Eds.): ICCES 2020, MMS 97, pp. 224–232, 2021.
https://doi.org/10.1007/978-3-030-64690-5_21