scholarly journals Multi-angle and nonuniform ground motions on cable-stayed bridges

2021 ◽  
pp. 875529302110513
Author(s):  
Eleftheria Efthymiou ◽  
Alfredo Camara
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Waves ◽  
Incidence Angle ◽  
Design Parameters ◽  
System Configuration ◽  
Cable System ◽  
Parametric Problem ◽  
Wide Range ◽  
Cable Stayed Bridges

The definition of the spatial variability of the ground motion (SVGM) is a complex and multi-parametric problem. Its effect on the seismic response of cable-stayed bridges is important, yet not entirely understood to date. This work examines the effect of the SVGM on the seismic response of cable-stayed bridges by means of the time delay of the ground motion at different supports, the loss of coherency of the seismic waves, and the incidence angle of the seismic waves. The focus herein is the effect of the SVGM on cable-stayed bridges with various configurations in terms of their length and of design parameters such as the pylon shape and the pylon–cable system configuration. The aim of this article is to provide general conclusions that are applicable to a wide range of canonical cable-stayed bridges and to contribute to the ongoing effort to interpret and predict the effect of the SVGM in long structures. This work shows that the effect of the SVGM on the seismic response of cable-stayed bridges varies depending on the pylon shape, height, and section dimensions; on the cable-system configuration; and on the response quantity of interest. Furthermore, the earthquake incidence angle defines whether the SVGM is important to the seismic response of the cable-stayed bridges. It is also confirmed that the SVGM excites vibration modes of the bridges that do not contribute to their seismic response when identical support motion is considered.

scholarly journals On the effect of multi-angle and spatially variable ground motions on cable-stayed bridges

2020 ◽  
Author(s):  
Eleftheria Efthymiou ◽  
Alfredo Camara
Keyword(s):  
Seismic Response ◽  
Seismic Waves ◽  
Incidence Angle ◽  
Design Parameters ◽  
Cable System ◽  
Parametric Problem ◽  
Wide Range ◽  
Support Excitation ◽  
Definition Of ◽  
Cable Stayed Bridges

The definition of the Spatial Variability of the Ground Motion (SVGM) is a com- plex and multi-parametric problem. Its effect on the seismic response of long and multiply-supported structures in general, and on cable-stayed bridges, in particular, is important but not entirely understood. This work examines the effect of the SVGM on the seismic response of cable-stayed bridges by means of the time delay of the earth- quake at different supports and of the loss of coherency of the seismic waves. The focus herein is the effect of the SVGM on cable-stayed bridges with various configu- rations in terms of their length and of design parameters, such as the pylon shape and the pylon–cable system configuration, combined with the influence of the incidence angle of the seismic waves. The aim of this paper is to provide general conclusions that are applicable to a wide range of cable-stayed bridges and to contribute to the ongoing effort to interpret and predict the effect of the SVGM. It has been found that the influence of the multi-support excitation on the seismic response of the bridges is strongly affected by the shape of the pylons, by the pylon–cable system configura- tion and by and the earthquake’s incidence angle. It is also observed that the SVGM excites vibration modes of the bridges that do not contribute to their seismic response when identical support motion is considered.

Surface topography effects on seismic ground motion and correlation with earthquake-induced landslide: An example of the JiuJiu peaks in 1999 Chi-Chi Taiwan earthquake

2020 ◽  
Author(s):  
Chun-Te Chen ◽  
Shiann-Jong Lee ◽  
Yu-Chang Chan
Keyword(s):  
Surface Topography ◽  
Seismic Response ◽  
Ground Motion ◽  
Seismic Waves ◽  
Velocity Structure ◽  
Seismic Hazard Assessment ◽  
Buffer Layers ◽  
Small Scale ◽  
Ground Shaking ◽  
Mesh Model

<p>The topography effect has been thriving investigated based on numerical modeling. It impacts the seismic ground shaking, usually amplifying the amplitude of shaking at top hills or ridges and de-amplifying at valleys. However, the correlation between the earthquake-induced landslide and the topographic amplification is relatively unexplored. To investigate the amplification of seismic response on the surface topography and the role in the Chi-Chi earthquake-induced landslide in the JiuJiu peaks area, we perform a 3D ground motion simulation in the JiuJiu peaks area of Taiwan based on the spectral element method. The Lidar-derived 20m resolution Digital Elevation Model (DEM) data was applied to build a mesh model with realistic terrain relief. To this end, in a steep topography area like the JiuJiu peaks, the designed thin buffer layers are applied to dampen the mesh distortion. The three doubling mesh layers near the surface accommodate a more excellent mesh model. Our results show the higher amplification of PGA on the tops and ridges of JiuJiu peaks than surrounding mountains, while the de-amplification mostly occurs near the valley and hillside. The relief topography could have a ±50% variation in PGA amplification for compression wave, and have much more variety in PGA amplification for shear wave, which could be in the range between -50% and +100%. We also demonstrate that the high percentages of the landslide distribution right after the large earthquake are located in the topographic amplified zone. The source frequency content interacts with the topographic feature, in general, small-scale topography amplifies the higher-frequency seismic waves. It is worthy of further investigating the interaction between the realistic topography and the velocity structure on how to impact the seismic response in the different frequency bands. We suggest that the topographic seismic amplification should be taking into account in seismic hazard assessment and landslide evaluation.</p>

scholarly journals Seismic Response Characteristics of Stabilizing Pile Based on Elastic-Plastic Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Honglue Qu ◽  
Ying Liu ◽  
Hao Luo ◽  
Huanguo Hu ◽  
Qindi Hu
Keyword(s):  
Plastic Zone ◽  
Seismic Response ◽  
Ground Motion ◽  
Seismic Design ◽  
Design Parameters ◽  
Plastic State ◽  
Elastic Plastic ◽  
Stabilizing Pile ◽  
Response Characteristics ◽  
Plastic Analysis

Stabilizing pile is widely used in the landslide controlling projects and shows excellent seismic performance under the action of earthquake. Therefore, in order to improve seismic design theory, it is of importance to study the seismic response characteristics of stabilizing pile based on elastic-plastic analysis. In view of this, elastic-plastic constitutive model was established to deduce the plastic zone of stabilizing pile. Based on elastic-plastic analysis, the seismic response characteristics and the influence of different section sizes, material strengths, and peak ground motion acceleration (PGA) were analyzed by ANSYS 3D. Resultantly, the elastic-plastic fourth-order tensor Cijklep was deduced, which can be used to calculate plastic strain of stabilizing pile under loading. Compared with Chinese code, the material of stabilizing pile working with elastic-plastic state will be decreased under the same section size and the same property. Furthermore, stabilizing pile is in the elastic stage at the beginning under the action of earthquake. With the increase of ground motion time, the section starts to exhibit elastic-plastic state and then the plastic zone expands gradually. Finally, the plastic zone runs through the whole section, resulting in the performance loss of the pile. In addition, under the different design parameters, pile shows different seismic response characteristics; namely, changing these parameters reasonably can improve the seismic design.

Influence of near-fault ground motion characteristics on the seismic response of cable-stayed bridges

2020 ◽  
Vol 18 (14) ◽  
pp. 6375-6403
Author(s):  
Chao Zhang ◽  
Jian-bing Lu ◽  
Hong-yu Jia ◽  
Zhi-chao Lai ◽  
Xu Li ◽  
...  
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Near Fault ◽  
Motion Characteristics ◽  
Near Fault Ground Motion ◽  
Cable Stayed Bridges

Ground motion spatial variability and cable-stayed bridges: do we need to consider the asynchronous motion?

2021 ◽  
Author(s):  
Eleftheria Efthymiou ◽  
Alfredo Camara
Keyword(s):  
Spatial Variability ◽  
Seismic Response ◽  
Ground Motion ◽  
Structural Integrity ◽  
Seismic Behaviour ◽  
Long Span ◽  
Seismic Fault ◽  
Differential Movement ◽  
Extensive Program ◽  
Cable Stayed Bridges

<p>Cable-stayed bridges are landmark structures and key parts of transportation networks worldwide. It is of vital importance that their integrity is ensured even under very large earthquakes. The spatial variability of the ground motion could be a significant aspect of the seismic behaviour of long-span cable-stayed bridges due to the differential movement of the pylons, which may lead to an amplified seismic response and increased damage in the pylons. The purpose of this paper is to examine the effect of the spatial variability of the ground motion on the seismic response of cable-stayed bridges with H-shaped pylons and various span lengths. Focus is placed on the pylons of the bridges because the constitute key members for the overall stability and structural integrity of the bridge. The study explores how important the spatial variability is in the seismic response of cable-stayed bridges by considering two different orientations of the structures with respect to the seismic fault in an extensive program of non-linear response-history analyses.</p>

scholarly journals Seismic rocking effects on a mine tower under induced and natural earthquakes

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Piotr Adam Bońkowski ◽  
Juliusz Kuś ◽  
Zbigniew Zembaty
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Ground Surface ◽  
Tall Buildings ◽  
Earthquake Ground Motion ◽  
Seismic Action ◽  
Seismic Effects ◽  
Copper Ore ◽  
Rotational Components ◽  
Natural Earthquakes

AbstractRecent research in engineering seismology demonstrated that in addition to three translational seismic excitations along x, y and z axes, one should also consider rotational components about these axes when calculating design seismic loads for structures. The objective of this paper is to present the results of a seismic response numerical analysis of a mine tower (also called in the literature a headframe or a pit frame). These structures are used in deep mining on the ground surface to hoist output (e.g. copper ore or coal). The mine towers belong to the tall, slender structures, for which rocking excitations may be important. In the numerical example, a typical steel headframe 64 m high is analysed under two records of simultaneous rocking and horizontal seismic action of an induced mine shock and a natural earthquake. As a result, a complicated interaction of rocking seismic effects with horizontal excitations is observed. The contribution of the rocking component may sometimes reduce the overall seismic response, but in most cases, it substantially increases the seismic response of the analysed headframe. It is concluded that in the analysed case of the 64 m mining tower, the seismic response, including the rocking ground motion effects, may increase up to 31% (for natural earthquake ground motion) or even up to 135% (for mining-induced, rockburst seismic effects). This means that not only in the case of the design of very tall buildings or industrial chimneys but also for specific yet very common structures like mine towers, including the rotational seismic effects may play an important role.

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