Landslide blockage length estimation for the man-made linear structures     

Chien-Yuan Chen  Tung-Lin Tsai 《Environmental Earth Sciences》2012,67(6):1781-1787

The landslide blockage length along a man-made linear structure, the Alishan railway, is analyzed herein. The Alishan railway runs from Chiayi City to the Alishan scenic area. Numerous landslide and debris flow disasters have blocked the railway since it began operations in 1911. In this study, features of landslides are interpreted from Spot 5 images along the Alishan railway. The results show that larger landslides along the railway exhibit a power-law distribution in frequency-area analysis. The railway blockage length by landslide and its frequency can be linearized by plotting it in a log scale for a blockage length over 0.02?km. The characteristics may be attributed to the fact that the landslide magnitude for its area and volume versus frequency exhibits a power-law distribution. It may thus be possible to estimate the blockage length of linear structures (e.g., railway and expressway) by landslides using the power-law distribution.  相似文献   

Stochastic sediment transport: anomalous diffusions and random movement     

Tsai  Christina W.  Hung  Serena Y.  Wu  Tsung-Han 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(2):397-413

Stochastic Environmental Research and Risk Assessment - A sediment particle in a flow not only follows the flow direction but also randomly diffuses through the surrounding fluid, because of the...  相似文献   

Development of a tunable friction pendulum system for semi‐active control of building structures under earthquake ground motions          下载免费PDF全文

Pan Peng  Zhang Dongbin  Zeng Yi  Tsai Yachun  Nie Xin 《地震工程与结构动力学》2018,47(8):1706-1721

The Friction Pendulum System (FPS) isolator is commonly used as a base isolation system in buildings. In this paper, a new tunable FPS (TFPS) isolator is proposed and developed to act as a semi‐active control system by combining the traditional FPS and semi‐active control concept. Theoretical analysis and physical tests were carried out to investigate the behavior of the proposed TFPS isolator. The experimental and theoretical results were in good agreement, both suggesting that the friction force of the TFPS isolator can be tuned to achieve seismic isolation of the structure. A series of numerical simulations of a base‐isolated structure equipped with the proposed TFPS isolator and subjected to earthquake ground motions were also conducted. In the analyses, the linear quadratic regulator (LQR) method was adopted to control the friction force of the proposed TFPS, and the applicability and effectiveness of the TFPS in controlling the structure's seismic responses were investigated. The simulation results showed that the TFPS can reduce the displacement of the isolation layer without significantly increasing the floor acceleration and inter‐story displacement of the superstructure, confirming that the TFPS can effectively control a base‐isolated structure under earthquake ground motions.  相似文献   

Particle transport mechanics and induced seismic noise in steep flume experiments with accelerometer-embedded tracers     

Florent Gimbert  Brian M. Fuller  Michael P. Lamb  Victor C. Tsai  Joel P. L. Johnson 《地球表面变化过程与地形》2019,44(1):219-241

Recent advances in fluvial seismology have provided solid observational and theoretical evidence that near-river seismic ground motion may be used to monitor and quantify coarse sediment transport. However, inversions of sediment transport rates from seismic observations have not been fully tested against independent measurements, and thus have unknown but potentially large uncertainties. In the present study, we provide the first robust test of existing theory by conducting dedicated sediment transport experiments in a flume laboratory under fully turbulent and rough flow conditions. We monitor grain-scale physics with the use of ‘smart rocks’ that consist of accelerometers embedded into manufactured rocks, and we quantitatively link bedload mechanics and seismic observations under various prescribed flow and sediment transport conditions. From our grain-scale observations, we find that bedload grain hop times are widely distributed, with impacts being on average much more frequent than predicted by existing saltation models. Impact velocities are observed to be a linear function of average downstream cobble velocities, and both velocities show a bed-slope dependency that is not represented in existing saltation models. Incorporating these effects in an improved bedload-induced seismic noise model allows sediment flux to be inverted from seismic noise within a factor of two uncertainty. This result holds over nearly two orders of magnitude of prescribed sediment fluxes with different sediment sizes and channel-bed slopes, and particle–particle collisions observed at the highest investigated rates are found to have negligible effect on the generated seismic power. These results support the applicability of the seismic-inversion framework to mountain rivers, although further experiments remain to be conducted at sediment transport near transport capacity. © 2018 John Wiley & Sons, Ltd.  相似文献   

Hybrid testing with model updating on steel panel damper substructures using a multi-axial testing system     

Kung-Juin Wang  Ming-Chieh Chuang  Keh-Chyuan Tsai  Chao-Hsien Li  Pu-Yuan Chin  Shen-Yuo Chueh 《地震工程与结构动力学》2019,48(3):347-365

This paper describes a series of hybrid tests performed on a steel panel damper (SPD) specimen by using a multi-axial testing system. The building under investigation adopted a three-dimensional six-story moment resisting frame with four SPDs installed at each story as the main seismic resisting system. The structural model was subjected to bi-directional ground excitations of three hazard levels. The finite element analysis program “Platform of Inelastic Structural Analysis for 3D Systems” (PISA3D) was used as the analysis kernel for hybrid tests. Relevant programming extensions in PISA3D were created to support geographically distributed hybrid testing in a general-purpose manner. An external displacement control (EDC) method was developed such that the actual boundary deformation of the specimen fixtures could be continuously measured and immediately compensated during tests. An online model updating (OMU) technique was developed and employed such that the material properties of the specimen could be identified directly from the specimen response during the test. The identified material properties were then immediately used to update those of the other relevant numerical elements to enhance the overall simulation fidelity. Superior flexibility of the underlying software architecture was well demonstrated in this series of hybrid tests since no hardcoding was used to support all the complex test settings. Test results confirmed the effectiveness of the proposed EDC method, as well as the capacity of the proposed OMU technique to satisfactorily and efficiently capture the hysteretic properties of the specimen.  相似文献   

Effect of wave non‐linearity on the standing‐wave‐induced seabed response     

C. P. Tsai  T. L. Lee  J. R. C. Hsu 《国际地质力学数值与分析法杂志》2000,24(11):869-892

A standing wave in front of a seawall may reach a height more than twice of its incident component. When excess pore pressure occurs, it may even induce seabed instability, hence endangering the structure. This issue was studied previously using only linear wave theory. In this paper, standing‐wave theory to a second‐order approximation is applied, in order to demonstrate the differences between these two solutions. The spatial and temporal variations in the instantaneous pore pressure are first calculated, in addition to their vertical distributions. The effects of wave height, water depth and the degree of soil saturation on pore pressure distributions are then discussed, followed by the net pore pressure averaged over one wave cycle. The results suggest the existence of a residual pore pressure in the seabed and its net pore pressure can be used to estimate the wave‐induced liquefaction potential in a soil column. It also indicates that, in deep water, the second‐order solution predicts that a negative pore pressure at an antinode which may be greater than a positive pressure. Overall, the second‐order solution is found to agree better with the experimental results of the pore pressures available, compared to the linear solution. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Improved time integration for pseudodynamic tests     

Shuenn-Yih Chang  Keh-Chyuan Tsai  Kuan-Chou Chen 《地震工程与结构动力学》1998,27(7):711-730

Converting the second-order differential equation to a first-order equation by integrating it with respect to time once as the governing equation of motion for a structural system can be very promising in the pseudodynamic testing. This was originally found and developed by Chang. The application of this time-integration technique to the Newmark explicit method is implimented and investigated in this paper. The main advantages of using the integral form of Newmark explicit method instead of the commonly used Newmark explicit method in a pseudodynamic test are: a less-error propagation effect, a better capability in capturing the rapid changes of dynamic loading and in eliminating the adverse linearization errors. All these improvements have been verified by theoretical studies and experimental tests. Consequently, for a same time step this time-integration technique may result in less-error propagation and achieve more accurate test results than applying the original form of Newmark explicit method in a pseudodynamic test due to these significant improvements. Thus, the incorporation of this proposed time-integration technique into the direct integration method for pseudodynamic testings is strongly recommended. © 1998 John Wiley & Sons, Ltd.  相似文献   

Liquefaction,building settlement,and residual strength of two residential areas during the 2016 southern Taiwan earthquake     

Tsai  Chi-Chin  Hwang  Yu-Wei  Lu  Chih-Chieh 《Acta Geotechnica》2020,15(6):1363-1379

Acta Geotechnica - On February 6, 2016, a moment magnitude (Mw) 6.4 earthquake struck southern Taiwan and devastated the Tainan area. Although the intensity of ground shaking was only moderate...  相似文献