TY - JOUR
T1 - Full-scale identification of the wave forces exerted on a floating bridge using inverse methods and directional wave spectrum estimation
AU - Petersen, Øyvind Wiig
AU - Øiseth, Ole
AU - Lourens, Eliz-Mari
PY - 2019
Y1 - 2019
N2 - The dynamic behaviour of long-span bridges is governed by stochastic loads from typically ambient excitation sources. In real life, these loads cannot be measured directly at full scale. However, inverse methods can be utilised to identify these unknown forces using response measurements together with a numerical model of the relevant structure. This paper presents a case study of full-scale identification of the wave forces on the Bgsøysund bridge, a long-span pontoon bridge that has been monitored since 2013. First, a numerical model of the structure is formed, resulting in a reduced-order state-space model that takes into account the frequency-dependent hydrodynamic mass and damping from the fluid, based on fitting of rational transfer functions. Using acceleration data of the structure measured during several events of moderate and strong seas, the wave forces are identified using stochastic-deterministic methods for combined state and input estimation. In addition, a separate frequency-domain assessment of the wave forces is performed, in which the spectral density of the first-order wave forces is constructed from an estimated directional wave field model driven by wave elevation data. When compared in the frequency domain, the force estimates from the two approaches are of comparable magnitude. However, uncertainties in the assumptions and models behind the force estimates from the two approaches still play a significant role.
AB - The dynamic behaviour of long-span bridges is governed by stochastic loads from typically ambient excitation sources. In real life, these loads cannot be measured directly at full scale. However, inverse methods can be utilised to identify these unknown forces using response measurements together with a numerical model of the relevant structure. This paper presents a case study of full-scale identification of the wave forces on the Bgsøysund bridge, a long-span pontoon bridge that has been monitored since 2013. First, a numerical model of the structure is formed, resulting in a reduced-order state-space model that takes into account the frequency-dependent hydrodynamic mass and damping from the fluid, based on fitting of rational transfer functions. Using acceleration data of the structure measured during several events of moderate and strong seas, the wave forces are identified using stochastic-deterministic methods for combined state and input estimation. In addition, a separate frequency-domain assessment of the wave forces is performed, in which the spectral density of the first-order wave forces is constructed from an estimated directional wave field model driven by wave elevation data. When compared in the frequency domain, the force estimates from the two approaches are of comparable magnitude. However, uncertainties in the assumptions and models behind the force estimates from the two approaches still play a significant role.
KW - structural monitoring
KW - wave force
KW - force identification
KW - floating bridge
KW - wave field
KW - Structural monitoring
KW - Wave force
KW - Floating bridge
KW - Force identification
KW - Wave field
UR - http://www.scopus.com/inward/record.url?scp=85056278309&partnerID=8YFLogxK
U2 - 10.1016/j.ymssp.2018.10.040
DO - 10.1016/j.ymssp.2018.10.040
M3 - Article
SN - 0888-3270
VL - 120
SP - 708
EP - 726
JO - Mechanical Systems and Signal Processing
JF - Mechanical Systems and Signal Processing
ER -