scholarly journals Dynamic Response Evaluation of Bridges Considering Aspect Ratio of Pier in Near-Fault and Far-Fault Ground Motions

2020 ◽  
Vol 10 (17) ◽  
pp. 6098
Author(s):  
Hyojoon An ◽  
Jong-Han Lee ◽  
Soobong Shin
Keyword(s):  
Aspect Ratio ◽  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Nonlinear Static Analysis ◽  
Structural System ◽  
Seismic Capacity ◽  
Near Fault ◽  
Aspect Ratios ◽  
Far Fault

The recent increase in earthquake activities has highlighted the importance of predicting the seismic response of structures. Damage to civil infrastructure, particularly bridges, can cause considerable human and property losses. The seismic performance of a structure should be evaluated based on the characteristics of structures and earthquakes. For this, this study defined the two main factors of ground motion and structural system that affect the seismic response of a structure. Ground motions, which are mainly dependent on the distance from the epicenter, were defined as near-fault and far-fault ground motions. Near-fault ground motion includes the characteristics of forward directivity and fling step. In addition to ground motion, the aspect ratio of the pier, as a representative factor of a structural system, influences the seismic behavior of bridges. Thus, this study assessed the seismic response of bridges with various aspect ratios under the near-fault and far-fault ground motion conditions. Nonlinear static analysis was first performed to evaluate the seismic capacity of the pier. Then modal and dynamic analyses were carried out to examine the effects of the aspect ratio and ground motion on the displacement and force response and the change in the natural frequency of the bridge.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

Simulation and analysis of a vertically irregular building subjected to near-fault ground motions

2020 ◽  
Vol 36 (3) ◽  
pp. 1485-1516
Author(s):  
Jui-Liang Lin ◽  
Wen-Hui Chen ◽  
Fu-Pei Hsiao ◽  
Yuan-Tao Weng ◽  
Wen-Cheng Shen ◽  
...  
Keyword(s):  
Numerical Model ◽  
Seismic Response ◽  
Ground Motion ◽  
Ground Motions ◽  
Far Field ◽  
Near Fault ◽  
Study Results ◽  
Rc Building ◽  
Near Fault Ground Motion ◽  
Story Building

A shaking table test of a three-story reinforced concrete (RC) building was conducted. The tested building is vertically irregular because of the first story’s elevated height and the third story’s added RC walls. In addition to far-field ground motions, near-fault ground motions were exerted on this building. A numerical model of the three-story building was constructed. Comparing with the test results indicates that the numerical model is satisfactory for simulating the seismic response of the three-story building. This validated numerical model was then further applied to look into two issues: the effective section rigidities of RC members and the effects of near-fault ground motions. The study results show the magnitude of the possible discrepancy between the actual seismic response and the estimated seismic response, when the effective section rigidities of the RC members are treated as in common practice. An incremental dynamic analysis of the three-story RC building subjected to one far-field and one near-fault ground motion, denoted as CHY047 and TCU052, respectively, was conducted. In comparison with the far-field ground motion, the near-fault ground motion is more destructive to this building. In addition, the effect of the selected near-fault ground motion (i.e. TCU052) on the building’s collapse is clearly identified.

scholarly journals Seismic Response of a Historical Masonry Bridge under Near and Far-fault Ground Motions

2021 ◽  
Author(s):  
Alper Özmen ◽  
Erkut Sayın
Keyword(s):  
Finite Element ◽  
Natural Disasters ◽  
Seismic Response ◽  
Ground Motions ◽  
Masonry Arch ◽  
Finite Element Software ◽  
Near Fault ◽  
Historical Masonry ◽  
Arch Bridges ◽  
Far Fault

Historical masonry arch bridges which might be vulnerable to natural disasters are important part of the cultural heritage. Natural disasters, especially earthquakes can inflict damage to these structural systems. This paper aims to investigate a comparison of the effects of near and far-fault ground motions on the seismic response of masonry arch bridges under different earthquakes. Kalender masonry arch bridge which is located in Ergani, Turkey is selected as a numerical model. For this purpose, three-dimensional finite element model of the bridge is generated with ANSYS finite element software with macro modelling approach. Seismic response of the bridge is assessed by means of time-history analyses. The near-fault and far-fault ground motions, which have approximately equal peak ground accelerations, of 1979 Imperial Valley, 1999 Chi-Chi, 1999 Kocaeli and 2010 Darfield earthquakes are considered for the analyses. Comparisons between maximum displacements, maximum and minimum stress, which were acquired from the dynamic analyses of the masonry bridge subjected to each fault effect, are obtained. The study demonstrates that far-fault ground motions are as important as near-fault ground motions and it can be used together with near-fault ground motion for further evaluation of such historical masonry bridges.

Proposed methodology for estimating the magnitude at which subduction megathrust ground motions and source dimensions exhibit a break in magnitude scaling: Example for 79 global subduction zones

2020 ◽  
Vol 36 (3) ◽  
pp. 1271-1297
Author(s):  
Kenneth W. Campbell
Keyword(s):  
Ground Motion ◽  
Subduction Zones ◽  
Ground Motions ◽  
Seismic Source ◽  
Scaling Relations ◽  
Megathrust Earthquakes ◽  
Source Dimensions ◽  
Magnitude Scaling ◽  
Aspect Ratios ◽  
Source Scaling

In this article, I propose a method for estimating the magnitude [Formula: see text] at which subduction megathrust earthquakes are expected to exhibit a break in magnitude scaling of both seismic source dimensions and earthquake ground motions. The methodology is demonstrated by applying it to 79 global subduction zones defined in the literature, including Cascadia. Breakpoint magnitude is estimated from seismogenic interface widths, empirical source scaling relations, and aspect ratios of physically unbounded earthquake ruptures and their uncertainties. The concept stems from the well-established observation that source-dimension and ground motion scaling decreases for shallow continental (primarily strike-slip) earthquakes when rupture exceeds the seismogenic width of the fault. Although a scaling break for megathrust earthquakes is difficult to observe empirically, all of the instrumentally recorded historical [Formula: see text] mega-earthquakes have occurred on subduction zones with [Formula: see text] (8.1–8.9), consistent with an observed break in source scaling relations derived from these same events. The breakpoint magnitudes derived in this study can be used to constrain the magnitude at which the scaling of ground motion is expected to decrease in subduction ground motion prediction equations.

Deterministic 3D Ground-Motion Simulations (0–5 Hz) and Surface Topography Effects of the 30 October 2016 Mw 6.5 Norcia, Italy, Earthquake

2021 ◽  
Author(s):  
Arben Pitarka ◽  
Aybige Akinci ◽  
Pasquale De Gori ◽  
Mauro Buttinelli
Keyword(s):  
Surface Topography ◽  
Ground Motion ◽  
Seismic Station ◽  
Ground Motions ◽  
Peak Ground Velocity ◽  
Earth Model ◽  
Rupture Directivity ◽  
Epicentral Area ◽  
Near Fault ◽  
Local Topography

ABSTRACT The Mw 6.5 Norcia, Italy, earthquake occurred on 30 October 2016 and caused extensive damage to buildings in the epicentral area. The earthquake was recorded by a network of strong-motion stations, including 14 stations located within a 5 km distance from the two causative faults. We used a numerical approach for generating seismic waves from two hybrid deterministic and stochastic kinematic fault rupture models propagating through a 3D Earth model derived from seismic tomography and local geology. The broadband simulations were performed in the 0–5 Hz frequency range using a physics-based deterministic approach modeling the earthquake rupture and elastic wave propagation. We used SW4, a finite-difference code that uses a conforming curvilinear mesh, designed to model surface topography with high numerical accuracy. The simulations reproduce the amplitude and duration of observed near-fault ground motions. Our results also suggest that due to the local fault-slip pattern and upward rupture directivity, the spatial pattern of the horizontal near-fault ground motion generated during the earthquake was complex and characterized by several local minima and maxima. Some of these local ground-motion maxima in the near-fault region were not observed because of the sparse station coverage. The simulated peak ground velocity (PGV) is higher than both the recorded PGV and predicted PGV based on empirical models for several areas located above the fault planes. Ground motions calculated with and without surface topography indicate that, on average, the local topography amplifies the ground-motion velocity by 30%. There is correlation between the PGV and local topography, with the PGV being higher at hilltops. In contrast, spatial variations of simulated PGA do not correlate with the surface topography. Simulated ground motions are important for seismic hazard and engineering assessments for areas that lack seismic station coverage and historical recordings from large damaging earthquakes.

Numerical Modeling of Near Fault Seismic Ground Motion for Denali Fault

2021 ◽  
Vol 12 (2) ◽  
pp. 0-0
Keyword(s):  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Numerical Study ◽  
Ground Motions ◽  
Numerical Results ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Denali Fault ◽  
Near Fault ◽  
Good Agreement

An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. This earthquake ruptured 340 km along Susitna Glacier, Denali and Totschunda faults in central Alaska. The peak ground acceleration (PGA) was recorded about 0.32 g at station PS10, which was located 3 km from the fault rupture. The PGA would have recorded a high value, if more instruments had been installed in the region. A numerical study has been conducted to find out the possible ground motion record that could occur at maximum horizontal slip during the Denali earthquake. The current study overcomes the limitation of number of elements to model the Denali fault. These numerical results are compared with observed ground motions. It is observed that the ground motions obtained through numerical analysis are in good agreement with observed ground motions. From numerical results, it is observed that the possible expected PGA is 0.62 g at maximum horizontal slip of Denali fault.

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