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In-plane dynamic Green's functions for inclined and uniformly distributed loads in a multi-layered transversely isotropic half-space

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Earthquake Engineering and Engineering Vibration 2018年第2期17卷 293-309页

作者： ba zhenning Kang Zeqing Liang Jianwen Department of Civil Engineering Tianjin UniversityTianjin 300072China Key Laboratory of Coast Civil Structure Safety(Tianjin University) Tianjin 300072China

The dynamic stiffness method combined with the Fourier transform is utilized to derive the in-plane Green’s functions for inclined and uniformly distributed loads in a multi-layered transversely isotropic（TI）*** loaded layer is fixed to obtain solutions restricted in it and the corresponding reactions forces,which are then applied to the total system with the opposite *** adding solutions restricted in the loaded layer to solutions from the reaction forces,the global solutions in the wavenumber domain are obtained,and the dynamic Green’s functions in the space domain are recovered by the inverse Fourier *** presented formulations can be reduced to the isotropic case developed by Wolf（1985）,and are further verified by comparisons with existing solutions in a uniform isotropic as well as a layered TI halfspace subjected to horizontally distributed loads which are special cases of the more general problem *** deduced Green’s functions,in conjunction with boundary element methods,will lead to significant advances in the investigation of a variety of wave scattering,wave radiation and soil-structure interaction problems in a layered TI *** numerical results are given to investigate the influence of material anisotropy,frequency of excitation,inclination angle and layered on the responses of displacement and stress,and some conclusions are drawn.

关键词： Green's functions transversely isotropic medium multi-layered half-space stiffness method dynamic response

Scattering and diffraction of plane SH-waves by periodically distributed canyons

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Earthquake Engineering and Engineering Vibration 2016年第2期15卷 325-339页

作者： ba zhenning Liang Jianwen Zhang Yanju Department of Civil Engineering Tianjin University Key Laboratory of Coast Civil Structure Safety (Tianjin University) Ministry of Education

A new method is presented to study the scattering and diffraction of plane SH-waves by periodically distributed canyons in a layered half-space. This method uses the indirect boundary element method combined with Green＇s functions of uniformly distributed loads acting on periodically distributed inclined lines. The periodicity feature of the canyons is exploited to limit the discretization effort to a single canyon, which avoids errors induced by the truncation of the infinite boundary, and the computational complexity and the demand on memory can be significantly reduced. Furthermore, the total wave fields are decomposed into the free field and scattered field in the process of calculation, which means that the method has definite physical meaning. The implementation of the method is described in detail and its accuracy is verified. Parametric studies are performed in the frequency domain by taking periodically distributed canyons of semi-circular and semi-elliptic cross-sections as examples. Numerical results show that the dynamic responses of periodically distributed canyons can be quite different from those for a single canyon and significant dynamic interactions exist between the canyons.

关键词： periodically layered uniformly verified decomposed truncation elliptic discretization scattered circular

Diffraction of SH-waves by topographic features in a layered transversely isotropic half-space

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Earthquake Engineering and Engineering Vibration 2017年第1期16卷 11-22页

作者： ba zhenning Liang Jianwen Zhang Yanju Department of Civil Engineering Tianjin University Tianjin 300072 China Key Laboratory of Coast Civil Structure Safety ( Tianjin University) Ministry of Education Tianjin 300072 China

Abstract： The scattering of plane SH-waves by topographic features in a layered transversely isotropic （TI） half-space is investigated by using an indirect boundary element method （IBEM）. Firstly, the anti-plane dynamic stiffness matrix of the layered TI half-space is established and the free fields are solved by using the direct stiffness method. Then, Green＇s functions are derived for uniformly distributed loads acting on an inclined line in a layered TI half-space and the scattered fields are constructed with the deduced Green＇s functions. Finally, the free fields are added to the scattered ones to obtain the global dynamic responses. The method is verified by comparing results with the published isotropic ones. Both the steady-state and transient dynamic responses are evaluated and discussed. Numerical results in the frequency domain show that surface motions for the TI media can be significantly different from those for the isotropic case, which are strongly dependent on the anisotropy property, incident angle and incident frequency. Results in the time domain show that the material anisotropy has important effects on the maximum duration and maximum amplitudes of the time histories.

关键词： wave scattering and diffraction Green's function transversely isotropic SH-waves indirect boundaryelement method

An end-to-end 3D seismic simulation of underground structures due to point dislocation source by using an FK-FEM hybrid approach

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Frontiers of Structural and Civil Engineering 2022年第12期16卷 1515-1529页

作者： zhenning ba Jisai FU Zhihui ZHU Hao ZHONG State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300350China National Engineering Research Center of High Speed Railway Construction Technology Central South UniversityChangsha 410075China School of Civil Engineering Central South UniversityChangsha 410075China

based on the domain reduction idea and artificial boundary substructure method,this paper proposes an FK-FEM hybrid approach by integrating the advantages of FK and FEM(i.e.,FK can efficiently generate high-frequency three translational motion,while FEM has rich elements types and constitutive models).An advantage of this approach is that it realizes the entire process simulation from point dislocation source to underground *** with the plane wave field input method,the FK-FEM hybrid approach can reflect the spatial variability of seismic motion and the influence of source and propagation *** approach can provide an effective solution for seismic analysis of underground structures under scenario of earthquake in regions where strong earthquakes may occur but are not recorded,especially when active faults,crustal,and soil parameters are *** Daikai subway station as an example,the seismic response of the underground structure is simulated after verifying the correctness of the approach and the effects of crustal velocity structure and source parameters on the seismic response of Daikai station are *** this example,the influence of velocity structure on the maximum interlayer displacement angle of underground structure is 96.5%and the change of source parameters can lead to the change of structural failure direction.

关键词： source-to-structure simulation FK-FEM hybrid approach underground structures point dislocation source

2.5D scattering of incident plane SH waves by a canyon in layered half-space

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Earthquake Science 2010年第1期23卷 25-33页

作者： zhenning ba Jianwen Liang Department of Civil Engineering Tianjin University Tianjin 300072 China

This paper presents 2.5D scattering of incident plane SH waves by a canyon in layered half-space by the indirect boundary element method (IBEM). The free field response is carried out to give the displacements and stresses on the line which forms boundary of the canyon. The fictitious uniform moving loads are applied to the same line to calculate the Green's functions for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The displacements due to the free field and from the fictitious uniform moving loads have to be added to obtain the whole motion. The numerical results are carried out for the cases of a canyon in homogenous and in one layer over bedrock. The results show that the 2.5D wave scattering problem is essentially different from the 2D case, and there exist distinct differences between the wave amplification by a canyon in layered half-space and that in homogeneous half-space. The reasons for the distinct difference are explored, and the effects of the thickness and stiffness of the layer on the amplification are discussed.

关键词： canyon layered half-space plane SH wave amplification 2.5D scattering

Physics-based seismic analysis of ancient wood structure:fault-to-structure simulation

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 727-740页

作者： ba zhenning Fu Jisai Wang Fangbo Liang Jianwen Zhang Bin Zhang Long State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation (Tianjin University)Tianjin 300350China School of Civil Engineering Tianjin UniversityTianjin 300350China Administrative Office of the Summer Palace Beijing 100091China School of Architecture Tianjin UniversityTianjin 300072China

based on the domain reduction method,this study employs an SEM-FEM hybrid workflow which integrates the advantages of the spectral element method(SEM)for flexible and highly efficient simulation of seismic wave propagation in a three-dimensional(3D)regional-scale geophysics model and the finite element method(FEM)for fine simulation of structural response including soil-structure interaction,and performs a physics-based simulation from initial fault rupture on an ancient wood *** verification of the hybrid workflow,a large-scale model of an ancient wood structure in the Beijing area,The Tower of Buddhist Incense,is established and its responses under the 1665 Tongxian earthquake and the 1730 Yiheyuan earthquake are *** results from the simulated ground motion and seismic response of the wood structure under the two earthquakes demonstrate that this hybrid workflow can be employed to efficiently provide insight into the relationships between geophysical parameters and the structural response,and is of great significance toward accurate input for seismic simulation of structures under specific site and fault conditions.

关键词： spectral element method finite element method fault-to-structure simulation physical model domain reduction method

Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅰ)

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Earthquake Science 2012年第4期25卷 275-285页

作者： Jianwen Liang Ji Zhang zhenning ba Department of Civil Engineering Tianjin University Tianjin Key Laboratory of Civil Engineering Structures and New Materials

Amplification of in-plane seismic ground motion by underground group cavities in layered half-space is studied both in frequency domain and time domain by using indirect boundary element method （IBEM）, and the effect of cavity interval and spectrum of incident waves on the amplification are studied by numerical examples. It is shown that there may be large interaction between cavities, and group cavities with certain intervals may have significant amplification to seismic ground motion. The amplification of PGA （peak ground acceleration） and its PRS （peak response spectrum） can be increased up to 45.2% and 84.4%, for an example site in Tianjin, under the excitation of Taft wave and E1 Centro wave; and group cavities may also affect the spectra of the seismic ground motion. It is suggested that the effect of underground group cavities on design seismic ground motion should be considered.

关键词： underground group cavity amplification in-plane seismic ground motion time domain frequency domain indirect boundary element method (IBEM)

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3D seismic response of a 2D hill-valley staggered topography modeled by a 2.5D multi-domain IBEM

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Earthquake Science 2019年第3期32卷 125-142页

作者： zhenning ba Qiaozhi Sang Jianwen Liang Department of Civil Engineering Tianjin UniversityTianjin 300072China Key Laboratory of Coast Civil Structure Safety(Tianjin University) Ministry of EducationTianjin 300072China

A two and a half dimensional(2.5D)multi-domain indirect boundary element method(IBEM)is developed to study the wave scattering of obliquely incident P-,SV-and SH-waves by a hill-valley staggered topography in a multi-layered *** IBEM algorithm includes using 2.5D full-space and half-space Green’s functions to construct scattered fields in decomposed closed and opened half-space regions,respectively,and using the dynamic stiffness method to solve the free *** regions are finally integrated by introducing the compatibility conditions to obtain the total wave *** proposed 2.5D IBEM has the flexibility in dealing with complex boundaries by directly applying the fictitious loads on the regions’boundaries,with a less storage requirement compared to the full 3D ***,by combining the specific advantages of the two kinds of Green’s functions,the method is well suitable for handling coupled topographies with high *** method is validated by comparison with published results for a single valley as well as a single hill *** effects of height-to-width ratio of hill and layering on dynamic responses are further parametrically investigated by numerical implementations in frequency *** show that the interaction between valley and hills can lead to a more significant amplification within the valley region,and dynamic responses are deeply influenced by the height-to-width of hill,simultaneously depending on incident angle and ***,the site effects become more complex when the stratification feature is taken into account.

关键词： 2.5D multi-domain IBEM Green’s functions for moving load hill-valley staggered topography wave scattering layered half-space

Seismic analysis of high-speed railway irregular bridge–track system considering V-shaped canyon effect

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Railway Engineering Science 2022年第1期30卷 57-70页

作者： Zhihui Zhu Yongjiu Tang zhenning ba Kun Wang Wei Gong Department of Civil Engineering Central South UniversityChangsha 410075 National Engineering Laboratory for High Speed Railway Construction Changsha 410075China Department of Civil Engineering Tianjin UniversityTianjin 300350China|

To explore the effect of canyon topography on the seismic response of railway irregular bridge-track system that crosses a V-shaped canyon, seismic ground motions of the horizontal site and V-shaped canyon site were simulated through theoretical analysis with 12 earthquake records selected from the Pacific Earthquake Engineering Research Center(PEER) Strong Ground Motion Database matching the site condition of the *** seismic response analyses of an existing 11-span irregular simply supported railway bridge-track system were performed under the simulated spatially varying ground motions. The effects of the V-shaped canyon topography on the peak ground acceleration at bridge foundations and seismic responses of the bridge-track system were analyzed. Comparisons between the results of horizontal and V-shaped canyon sites show that the top relative displacement between adjacent piers at the junction of the incident side and the back side of the V-shaped site is almost two times that of the horizontal site, which also determines the seismic response of the fastener. The maximum displacement of the fastener occurs in the V-shaped canyon site and is 1.4 times larger than that in the horizontal site. Neglecting the effect of V-shaped canyon leads to the inappropriate assessment of the maximum seismic response of the irregular high-speed railway bridge-track system. Moreover, engineers should focus on the girder end to the left or right of the two fasteners within the distance of track seismic damage.

关键词： V-shaped canyon Nonlinear seismic response Irregular bridge Simply supported railway bridge Analytical solution Topography effect