Near-fault seismic risk assessment of simply supported bridges

2020 ◽  
Vol 36 (4) ◽  
pp. 1645-1669 ◽  
Author(s):  
Jian Zhong ◽  
Linwei Jiang ◽  
Yutao Pang ◽  
Wancheng Yuan
Keyword(s):  
Seismic Risk ◽  
Fault Location ◽  
Hazard Analysis ◽  
Near Field ◽  
Peak Ground Velocity ◽  
Seismic Demand ◽  
Simply Supported ◽  
Directivity Effect ◽  
Near Fault ◽  
Bridge Models

Bridges tend to sustain excessive seismic demand (e.g. displacement) under pulse-like ground motions attributing to the effect of forward directivity, which is of high likely to occur at locations near the fault rupture. This study tries to incorporate the pulse effect into the probabilistic seismic hazard analysis (PSHA) and probabilistic seismic demand analysis (PSDA) framework, which are combined to quantify the risk of earthquake-induced damage in the near-fault location. The near-fault PSDA and PSHA are established and connected conditioned on peak ground velocity (PGV). Four sets of typical simply supported bridge types with the varying heights, representing the range of the period, are simulated by taking account the strength and stiffness degradation associated with material and geometry nonlinearity. The detailed investigation of the near-fault seismic risk is performed for these bridge models located at representative near-fault sites namely 5, 10, 15, and 20 km, respectively. The results reveal that near-field directivity effect strongly impacts the bridge damage risk with the observation of higher risk at the closer site; the bridges with the period of approximately Tp/2(pulse period) tend to experience the highest seismic risk, and the relative vulnerability of four bridge types is also compared.

scholarly journals Analysis of the Seismic Demand of High-Performance Buckling-Restrained Braces under a Strong Earthquake and Its Aftershocks

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Luqi Xie ◽  
Jing Wu ◽  
Qing Huang ◽  
Chao Tong
Keyword(s):  
Plastic Deformation ◽  
Ground Motion ◽  
Strong Earthquake ◽  
High Performance ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Threshold Value ◽  
Seismic Demand ◽  
Near Fault ◽  
Probabilistic Seismic Demand

The analysis of the ductility and cumulative plastic deformation (CPD) demand of a high-performance buckling-restrained brace (HPBRB) under a strong earthquake and its aftershocks is conducted in this paper. A combination of three continuous excitations with the same ground motion is used to simulate the affection of a strong earthquake and its aftershocks. A six-story HPBRB frame (HPBRBF) is taken as an example to conduct the incremental dynamic analysis (IDA). The seismic responses of the HPBRBF under one, two, and three constant continuous ground motions are compared. The IDA result indicates that the ductility and CPD demand of the BRBs under the three constant continuous ground motions are significantly larger than that excited by only one. Probabilistic seismic demand analysis (PSDA) is performed using seven near-fault ground motions and seven far-fault ground motions to consider the indeterminacy of ground motion. The probabilistic seismic demand curves (PSDCs) for the ductility and CPD demand for the HPBRB under the strong earthquake and its aftershocks are obtained in combining the probabilistic seismic hazard analysis. The results indicate that the AISC threshold value of the CPD with 200 is excessively low for a HPBRBF which suffers the continuous strong aftershocks with near-fault excitations, and a stricter threshold value should be suggested to ensure the ductility and plastic deformation capacity demand of the HPBRB.

Ground Motion Selection in the Near-Fault Region considering Directivity-Induced Pulse Effects

2019 ◽  
Vol 35 (2) ◽  
pp. 759-786 ◽  
Author(s):  
Karim Tarbali ◽  
Brendon A. Bradley ◽  
Jack W. Baker
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Ground Motions ◽  
Seismic Hazard Analysis ◽  
Response Analysis ◽  
Seismic Demand ◽  
Ground Motion Selection ◽  
Near Fault ◽  
Fault Region

This paper focuses on the selection of ground motions for seismic response analysis in the near-fault region, where directivity effects are significant. An approach is presented to consider forward directivity velocity pulse effects in seismic hazard analysis without separate hazard calculations for ‘pulse-like’ and ‘non-pulse-like’ ground motions, resulting in a single target hazard (at the site of interest) for ground motion selection. The ability of ground motion selection methods to appropriately select records that exhibit pulse-like ground motions in the near-fault region is then examined. Applications for scenario and probabilistic seismic hazard analysis cases are examined through the computation of conditional seismic demand distributions and the seismic demand hazard. It is shown that ground motion selection based on an appropriate set of intensity measures (IMs) will lead to ground motion ensembles with an appropriate representation of the directivity-included target hazard in terms of IMs, which are themselves affected by directivity pulse effects. This alleviates the need to specify the proportion of pulse-like motions and their pulse periods a priori as strict criteria for ground motion selection.

Rapid Detection of Earthquake Rupture Directivity Using Strong Ground Motion Data in Taiwan

2020 ◽  
Author(s):  
Cheng-Feng Wu ◽  
Ting-Li Lin ◽  
Ying-Chi Chen
Keyword(s):  
Real Time ◽  
Detection System ◽  
Near Field ◽  
Strong Motion ◽  
Peak Ground Velocity ◽  
Earthquake Rupture ◽  
Rupture Directivity ◽  
Motion Data ◽  
Directivity Effect ◽  
Source Studies

<p>In the past decade, there have been several disaster earthquakes occurred in Taiwan.<br>From the observed data of the disaster earthquakes, the stations located in the source<br>rupture direction have obvious directivity pulses, and the distribution of the earthquake<br>disaster is related to the peak ground velocity. Therefore, how to use a large and high-<br>dense seismic database to develop a near-real-time detection system on the earthquake<br>rupture directivity, which is a very important task in Taiwan. In this study, we determine<br>the earthquake rupture directivity using near-field velocity data from 1991 to 2018, which<br>were collected under the Taiwan Strong Motion Instrument Program (TSMIP). The used<br>method is mainly constructed in the interpolation of the peak-ground-velocity map and<br>the directional attenuation regression analysis. Through the analysis of moderate-to-large<br>magnitude (M L > 5.5) seismic events, the source rupture directivity can be detected<br>effectively and quickly by the applied method. The detection results are also comparable<br>with those from the previous source studies. We also find out a linear relationship between<br>the directivity effect and earthquake magnitude. Since the TSMIP station may provide<br>real-time services in the future, the detection system proposed by this research can quickly<br>provide disaster prediction information, which is of great importance for earthquake<br>emergency response and hazard mitigation.</p>

scholarly journals Co-Seismic Ionospheric Disturbance with Alaska Strike-Slip Mw7.9 Earthquake on 23 January 2018 Monitored by GPS

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 83
Author(s):  
Yongming Zhang ◽  
Xin Liu ◽  
Jinyun Guo ◽  
Kunpeng Shi ◽  
Maosheng Zhou ◽  
...  
Keyword(s):  
Fault Location ◽  
Ionospheric Disturbance ◽  
Near Field ◽  
Singular Spectrum Analysis ◽  
Maximum Amplitude ◽  
Strike Slip ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Total Electron Contents ◽  
Alaska Earthquake

The Mw7.9 Alaska earthquake at 09:31:40 UTC on 23 January 2018 occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Global positioning system (GPS) data were used to calculate the slant total electron contents above the epicenter. The singular spectrum analysis (SSA) method was used to extract detailed ionospheric disturbance information, and to monitor the co-seismic ionospheric disturbances (CIDs) of the Alaska earthquake. The results show that the near-field CIDs were detected 8–12 min after the main shock, and the typical compression-rarefaction wave (N-shaped wave) appeared. The ionospheric disturbances propagate to the southwest at a horizontal velocity of 2.61 km/s within 500 km from the epicenter. The maximum amplitude of CIDs appears about 0.16 TECU (1TECU = 1016 el m−2) near the epicenter, and gradually decreases with the location of sub-ionospheric points (SIPs) far away from the epicenter. The attenuation rate of amplitude slows down as the distance between the SIPs and the epicenter increases. The direction of the CIDs caused by strike-slip faults may be affected by the horizontal direction of fault slip. The propagation characteristics of the ionospheric disturbance in the Alaska earthquake may be related to the complex conditions of focal mechanisms and fault location.

scholarly journals Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Gansu Province ◽  
Mitigation Measures ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Acceleration Time Histories

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.

scholarly journals Installation Uncertainty of Field Level Calculation around a Base Station Antenna

2007 ◽  
Vol 3 (2) ◽  
pp. 115
Author(s):  
Antonio Šarolić ◽  
Borivoj Modlic
Keyword(s):  
Hazard Analysis ◽  
Near Field ◽  
Three Dimensional ◽  
Real Life ◽  
Base Station ◽  
Radiation Hazard ◽  
Specific Situation ◽  
Field Calculation ◽  
Single Antenna ◽  
Level Calculation

In the near field, the antenna pattern provided by the antenna manufacturer is generally not applicable, or shouldbe considered with caution, even for the single antenna in free space. In the real life, antenna is often surrounded by other conductive objects in the immediate vicinity. These objects tend to distort the antenna radiation pattern. Since the electromagnetic field calculation for the coverage or radiation hazard analysis depends on the three-dimensional antenna gain, this effect should be taken into account. This paper suggests the use of "installation uncertainty" that should be added to the field calculation. The amount of this quantity depends on the installation geometry and can be calculated numerically for a specific situation. This paper shows the results of numerical calculations for some typical antenna installation geometries.

Simulation of Palu IV Bridge Collapse using Near-Fault Ground Motions

2019 ◽  
Author(s):  
Iswandi Imran ◽  
Budi Santoso ◽  
Ary Pramudito ◽  
Muhammad Kadri Zamad
Keyword(s):  
Spatial Variation ◽  
Ground Motions ◽  
Time History ◽  
Seismic Demand ◽  
Fault Line ◽  
Near Fault ◽  
Failure Simulation ◽  
Bridge Collapse ◽  
Pulse Type ◽  
Bridge Bearing

<p>The earthquake near Palu, Sulawesi (Indonesia) on September 28, 2018 with a magnitude of M7.4 was caused by a shallow strike-slip of Palu-Koro fault. The earthquake and the subsequent tsunami have caused the collapse of the Ponulele Bridge (Palu IV Bridge). The steel box bowstring arch bridge was located near-fault regions (within 1,5 km from fault line) that have not been identified during the design process. This bridge may have been damaged by the presence of fling-step pulses in the near-fault pulse-type ground motions that increases the damaging potential of such ground motions. This paper presents the failure simulation of the bridge subjected to the near fault pulse type time history with spatial variation ground motions applied on multiple bridge supports. From the simulation, it is concluded that the near fault effects and the spatial variation of the ground motion have increased significantly the seismic demand on the bridge. This increase causes the failure in the anchorage of the bridge bearing system.</p>

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