An improved method of hydrodynamic pressure calculation for circular hollow piers in deep water under earthquake

Advances in Civil Engineering

Liu

et al. 2021

Based on the Hong Kong-Zhuhai-Macao project, considering the fluid-structure interaction and soil-structure interaction, the seismic response of a sea-crossing continuous girder bridge is analyzed. Three-dimensional nonlinear numerical bridge model is developed, in which the hydrodynamic force is represented by added mass and pile-soil interaction is represented by p-y elements. Meanwhile, stratification of soil is considered in the free field analysis. Through the comparison of responses of the bridge cases, the effects of earthquake-induced hydrodynamic force and pile-soil interaction are studied. For the influence of hydrodynamic force, the results show that it is relatively slight as compared with pile-soil interaction; moreover pile foundation is more sensitive to it than other bridge components. The influence of pile-soil interaction is relatively significant. When both of the interactions are considered, the influence is not a simple superposition of acting alone, so it is recommended to consider both factors in dynamic analysis.

Section: Introductionmentioning

confidence: 99%

Influence of Water‐Structure and Soil‐Structure Interaction on Seismic Performance of Sea‐Crossing Continuous Girder Bridge

Guo

Advances in Civil Engineering

Liu

et al. 2021

“…Additionally, effect of the hydrodynamic pressure can be simply modeled as an 'added mass' when the surface wave and water compressibility are ignored. Assuming the structure rigid, the simplified formulas of the added mass for the earthquake induced hydrodynamic pressure on circular cylinder and elliptical cylinders were given by Jiang et al (2017), Li and Yang (2013), and Wang et al (2018a). Considering the flexible of the structure, a simple and accurate added mass representation was also presented by Han and Xu (1996).…”

Section: Introductionmentioning

confidence: 99%

“…A special boundary method based on the use of a complete and non-singular set of Trefftz functions was presented for hydrodynamic pressure on axisymmetric offshore structures (Sun and Nogami 2010;Avilés and Li 2001). The free surface wave effect on the water-cylinder interaction is significant in wave force (Ti et al 2020), but it has been validated that free surface waves have less effect on the earthquake-induced hydrodynamic force on cylinders by Liaw and Chopra (1974) and Li and Yang (2013).…”

Section: Introductionmentioning

confidence: 99%

An accurate frequency-domain model of water interaction with cylinders of arbitrary shape during earthquakes

Zhao

et al. 2021

ABEN

An accurate frequency domain model is proposed to analyze the seismic response of uniform vertical cylinders with arbitrary cross section surrounded by water. According to the boundary conditions and using the variables separation method, the vertical modes of the hydrodynamic pressure are firstly obtained. Secondly, the three-dimensional wave equation can be simplified to a two-dimensional Helmholtz equation. Introducing the scaled boundary coordinate, a scaled boundary finite element (SBFE) equation which is a linear non-homogeneous second-order ordinary equation is derived by weighted residual method. The dynamic-stiffness matrix equation for the problem is furtherly derived. The continued fraction is acted as the solution of the dynamic-stiffness matrix for cylinder dynamic interaction of cylinder with infinite water. The coefficient matrices of the continued fraction are derived recursively from the SBFE equation of dynamic-stiffness. The accuracy of the present method is verified by comparing the hydrodynamic force on circular, elliptical and rectangle cylinders with the analytical or numerical solutions. Finally, the proposed model is used to analyze the natural frequency and seismic response of cylinders.

“…It should be noted that the incompressible water can be replaced by an added mass [3]. Recently, a series of simplified formulas to evaluate the added mass of a single cylinder are presented by assuming the cylinder rigid, such as the circular cylinder [18,19], the elliptical cylinder [20,21], the round-ended and rectangular cylinders [22], and the circular tapered cylinders [23]. In addition, the simple added mass models for a flexible cylinder vibrating in water were also proposed by Han and Xu [24], Yang and Li [25], and Wang et al [26].…”

Section: Introductionmentioning

confidence: 99%

Seismic Fragility Analysis of Bridge Group Pile Foundations considering Fluid-Pile-Soil Interaction

Zhang

2020

Shock and Vibration

The cross-sea bridges play an important role to promote the development of regional economy. These bridges located in earthquake-prone areas may be subjected to severe earthquakes during their lifetime. Group pile foundations have been widely used in cross-sea bridges due to their structural efficiency, ease of construction, and low cost. This paper investigates the seismic performance of bridge pile foundation based on the seismic fragility analysis. Based on the analysis platform OpenSees, the three-dimensional finite model of the bridge pile foundation is developed, where the pile-water interaction is replaced by the added mass method, nonlinear p-y, t-z, and q-z elements are used to simulate pile-soil interaction, and the displacement of the surface ground motion due to seismic excitations is applied on all spring supports. The seismic fragility curves of the bridge pile foundation are generated by using the earthquake records recommended by FEMA P695 as input motions. The curvature ductility based fragility curves are obtained using seismic responses for different peak ground accelerations. The effects of pile-water interaction, soil conditions, and different types of ground motions on the bridge pier fragilities are studied and discussed. Seismic fragility of the pier-group pile system shows that Sec C (the bottom section of the pier) is the most vulnerable section in the example fluid-structure-soil interaction (FSSI) system for all four damage LSs. The seismic responses of Sec E (a pile section located at the interface of the soil layer and water layer) are much lower than other sections. The parameter analysis shows that pile-water interaction has slight influence (less than 5%) on the fragility curves of the bridge pier. For the bridge group pile foundations considering the fluid-pile-soil interaction, PNF may induce larger seismic response than far-field (FF) and no-pulse near field (NNF). The bridge pile foundation in stiff soil is most vulnerable to seismic damage than soft condition.