Nonlinear dynamic response of sea-crossing bridges to 3D correlated wind and wave loads

Directional effects of correlated wind and waves on the dynamic response of long-span sea-crossing bridges

Nonlinear buffeting responses of a coastal long-span bridge under the coupled wind, wave and current loads

Uncertainties from random multiple factors bring great challenges for assessing response of long-span bridges. This study proposes a dynamic analysis framework by integrating the wind–wave–bridge system with Bayesian regularized back propagation neural network, and then investigates stochastic response of a cross-sea cable-stayed bridge under extreme wind and wave parameters. The wind–wave–bridge system involving wind–bridge and wave–bridge interactions is constructed to calculate dynamic response of the bridge by Newmark-β method, considering stationary fluctuating wind fields and multidirectional random wave fields. To reduce the calculation cost, a Bayesian regularized back propagation neural network model is introduced, and the model evaluation is carried out to illustrate its accuracy and efficiency. After performing small-scale finite element analyses, the response statistics are obtained and later used as the known samples for training the neural network. The power spectrum analyses of the deterministic results are performed to investigate the contribution mechanism of the wind and wave. Finally, the correlation between the bridge response and the single wind–wave parameter is given by uncertainty analysis of the Bayesian regularized back propagation neural network model. The results show that the proposed framework is capable of capturing the nonlinear bridge response resulting from nonlinear wind and wave loads, which, however, is significant different from that under wind alone. The bridge response receives significant contribution from wind and waves relative to the vibration characteristic of the bridge at smaller wind and wave loads. The contribution from vibration characteristic of the bridge becomes significant at larger wind and wave loads. The uncertainty analyses illustrate the significant effects of four wind and wave parameters on girder, tower, and submerged structure.

Serviceability analysis of sea-crossing bridges under correlated wind and wave loads

Dynamic response of a sea-crossing cable-stayed suspension bridge under simultaneous wind and wave loadings induced by a landfall typhoon

According to the characteristics of floating cranes, an affordable numerical method to model the floating cranes and the external excitations such as wind, wave and shimmy loads was proposed. Local coordinates modifying wind, wave and shimmy loads which are determined separately were combined in the global coordinate system according to the geometric positions. The spectra of wind loads and wave loads were converted into time domain separately according to the linear method, while a shimmy load is determined according to the Lagrange’s Equation. As an example, the external excitation caused by random wind, wave and shimmy loads on a 7500-ton giant floating crane were simulated, and the transient dynamic response was predicted and discussed. Focusing on the characteristics of structure of floating cranes, the research indicates that the dominant frequency of the wave load is low, as compared to wind and shimmy loads, and that the shimmy load is closely related to the environmental excitations such as wind and wave loads. The results also suggest that the transient response of the crane is mainly related to the shimmy load.

Directional effects on the nonlinear response of vehicle-bridge system under correlated wind and waves

Long-span bridges suspended from floating towers are a promising design concept to cross the strait with deep water depth. This paper presents an alternative dynamic simulation framework for floating suspension bridge by integrating the calculations of wave, radiation and wind loads with common software and computing scripts, and verifies the numerical models, including structure, wave load, radiation and wind load. Bridge schemes with different sag-to-span ratios inspired by a prototype long-span floating bridge were proposed. Static, modal and dynamic analyses are conducted through the developed simulation framework to obtain the bridge response. The influence of the sag-to-span ratio on the dynamic response of a long-span bridge suspended from floating towers under wave and wind conditions was investigated. The results indicate that the natural period of the floating bridge decreases with the reduction in the sag-to-span ratio, and the sag-to-span ratio significantly affects the dynamic response of the example floating bridge.

The analysis of dynamic response of seabed due to wave loading is of practical significance in design and construction of marine structures and offshore installations. Recently considerable efforts for this problem have been made with growing interest by many researchers and marine engineers, and many representative results have been achieved. It is obvious that wave loading plays a significant role in the evaluation of construction safety and seabed instability. But there are few results of research and engineering design that can consider the feature of wave loading and soil parameters together. The purpose of this paper is to establish a reasonable numerical model to simulate dynamic response of seabed under random wave loading. The dynamic relation between random wave and seabed can also be described through this model. Comparative studies are principally made between the proposed analysis considering actual feature of ocean situation and conventional analysis based on linear theory of regular wave. The effect of randomness of wave loading on the dynamic response of seabed is investigated. The necessity is also discussed about considering the influence of damping energy on propagating wave by porous seabed. In the conventional analyses of seabed dynamics, wave loading is basically treated as a deterministic process and is usually taken into consideration by using linear theory of regular wave. In fact, ocean wave is of intrinsic randomness in both time sequences and spatial distribution. The random nature of both wave and wave-induced loading will subsequently affect dynamic behavior of seabed. In this paper, the analyses which can consider characteristics of randomness of wave loading and dynamic interaction between seabed and random waves, are formulated in a stochastic framework. Integrated numerical analysis model is established by employing wave spectrum of AVERAGE JONSWAP. The comparative studies are conducted among the methods of conventional random analysis, proposed random analysis, and linear regular wave theory. The results show that the amplitudes of dynamic response of seabed subjected to random wave loading are larger than that of regular linear wave loading. Therefore the stochastic feature of wave loading has to be duly taken into account in the analysis for dynamic response of seabed.

The third-generation gravity base foundation, which consists of a concrete-based structure with infill aggregates, is designed for water depths greater than 20 m. In this study, a simplified method in the time domain for predicting the nonlinear dynamic response of the offshore wind turbine supported on the third-generation gravity base foundation is proposed. The results obtained by the proposed method are compared with 3D finite element simulations, and the consistency of the results verifies the reliability of the simplified method. In addition, the dynamic response of the wind turbine supported on GBF under wind and wave loads is investigated. The results indicate that the lateral dynamic responses of the GBF are more affected by the thrust force than by the distributed force when the wind loads are only considered; the maximum dynamic displacement of the GBF caused by the drag force is almost the same as that of the GBF caused by the inertia force when the wave loads are only considered, and the dynamic response of the GBF under combined wind and wave loads show a similar trend to that of the GBF under the wind loads only, especially the existence of a large displacement on the horizontal direction at the beginning of the loading.

Probabilistic analysis of monopile-supported offshore wind turbine in clay

Long-term fatigue analysis of multi-planar tubular joints for jacket-type offshore wind turbine in time domain

A comprehensive performance evaluation methodology for sea-crossing cable-stayed bridges under wind and wave loads

Shaking table tests and numerical analysis of monopile-supported offshore wind turbines under combined wind, wave and seismic loads

The main objective of this research is to investigate the response of the pre-piled offshore wind farm jacket structure when the structure undergoes operational cyclic (wind+wave) loads combined with earthquake loads. Hence, a two-layered soil condition was chosen, with the shallow-loose layer overlying a deep-denser layer. The scaled model of an exact jacket configuration was designed and tested in a centrifuge along with the wind tower and nacelle arrangement, which matches the dynamic properties of an equivalent 9MW turbine. Two cases were considered, one with lateral load (wind load) and another with no lateral load during the earthquake. The lateral load was applied at the nacelle level using an in-flight mass on a pneumatic piston arrangement to generate the equivalent pile head moment due to the wave and wind loads. The key findings are that the generation of excess pore pressures causes the soil to liquefy under strong earthquakes, eventually leading the structure to settle and rotate more than its allowable serviceability limit state (SLS). While it is evident that the lateral loads combined with seismic load cause excessive settlement and rotation, the structure also shows considerable settlement and rotation without any lateral load during the seismic event. Also, the effect of including operational wind and wave loads in combination with the seismic loads recommended by DNV-ST-0437 (2016) and DNV-RP-0585 (2021) are also discussed.