Equivalent linear analysis of seismic-isolated bridges subjected to near-fault ground motions with forward rupture directivity effect

2007 ◽  
Vol 29 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Murat Dicleli ◽  
Srikanth Buddaram
Keyword(s):  
Ground Motions ◽  
Linear Analysis ◽  
Rupture Directivity ◽  
Directivity Effect ◽  
Near Fault ◽  
Equivalent Linear ◽  
Isolated Bridges ◽  
Forward Rupture Directivity ◽  
Equivalent Linear Analysis

Performance of Seismic-Isolated Bridges in Relation to Near-Fault Ground-Motion and Isolator Characteristics

2006 ◽  
Vol 22 (4) ◽  
pp. 887-907 ◽  
Author(s):  
Murat Dicleli
Keyword(s):  
Ground Motion ◽  
Seismic Isolation ◽  
Elastic Stiffness ◽  
Rupture Directivity ◽  
Directivity Effect ◽  
Critical Design ◽  
Near Fault ◽  
Near Fault Ground Motion ◽  
Isolated Bridges ◽  
Forward Rupture Directivity

This paper investigates the performance of seismic-isolated bridges (SIBs) subjected to near-fault (NF) earthquakes with forward rupture directivity effect (FRDE) in relation to the isolator, substructure, and NF earthquake properties, and examines some critical design clauses in AASHTO's Guide Specifications for Seismic Isolation Design. It is found that the SIB response is a function of the number of velocity pulses, magnitude of the NF ground motion, and distance from the fault. Particularly, a reasonable estimation of the expected magnitude of the NF ground motion according to the characteristics of the bridge site is crucial for a correct design of the SIB. It is also found that the characteristic strength and post-elastic stiffness of the isolator may be chosen based on the characteristics of the NF earthquake. Furthermore, some of the AASHTO clauses are found to be not applicable to SIBs subjected to NF ground motions with FRDE.

Consideration of Three Seismic Isolation Performances as Design Objectives for Equivalent Linear Analysis of Bilinear Hysteretic Isolation Systems

2021 ◽  
pp. 2250001
Author(s):  
Shiang-Jung Wang ◽  
Yin-Nan Huang ◽  
Hsueh-Wen Lee ◽  
Yu-Wen Chang
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Linear Analysis ◽  
Analysis Procedure ◽  
Numerical Comparison ◽  
Near Fault ◽  
Equivalent Linear ◽  
Isolation Systems ◽  
Seismic Isolation Systems ◽  
Equivalent Linear Analysis

The design displacement, its corresponding acceleration performance, and the re-centering performance of bilinear hysteretic isolation systems are adopted as previously determined design objectives for equivalent linear analysis. To demonstrate the applicability and generalization of the analysis procedure, two sets of values for damping modification factors are employed in the analysis: those provided by ASCE/SEI 7-16, and those estimated for different ranges of the ratios of effective periods of seismic isolation systems to pulse periods of ground motions. To investigate a broad range of seismic responses of base-isolated structures, 15 pulse-like near-fault ground motions are used for numerical demonstration. The analysis procedure is numerically verified to be practically feasible. A numerical comparison also shows that the three design objectives previously determined in the analysis procedure are sufficiently conservative compared with analysis results from nonlinear dynamic response history, even when subjected to pulse-like near-fault ground motions. Regarding the approximation to maximum inelastic acceleration and displacement responses, it is particularly more conservative for the former when the design displacement is greater and when adopting values of the damping modification factors provided in ASCE/SEI 7-16. For the approximation to dynamic residual displacement responses, the influences of pulse-like near-fault ground motions and different design objectives on the re-centering performance of bilinear hysteretic isolation systems still need further study.

Improved Effective Damping Equation for Equivalent Linear Analysis of Seismic-Isolated Bridges

2006 ◽  
Vol 22 (1) ◽  
pp. 29-46 ◽  
Author(s):  
Murat Dicleli ◽  
Srikanth Buddaram
Keyword(s):  
Ground Motion ◽  
Nonlinear Response ◽  
Ground Motions ◽  
Linear Analysis ◽  
Frequency Characteristics ◽  
Accurate Estimation ◽  
Effective Period ◽  
Equivalent Linear ◽  
Isolated Bridges ◽  
Equivalent Linear Analysis

In this study, an improved effective damping (ED) equation is proposed to obtain more reasonable estimates of the actual nonlinear response of seismic-isolated bridges (SIB) using equivalent linear (EL) analysis procedure. For this purpose, first the EL analysis results using AASHTO's ED equation is evaluated using harmonic and seismic ground motions. The effect of several parameters such as substructure stiffness, isolator properties, and the intensity and frequency characteristics of the ground motion are considered in the evaluation. Next, the effect of the superstructure mass on the ED ratio is studied. It is found that the accuracy of the EL analysis results is affected by the frequency characteristics and intensity of the ground motion. It is also demonstrated that AASHTO's ED equation should incorporate the effective period of the SIB and isolator properties for a more accurate estimation of the seismic response quantities. A new ED equation that includes such parameters is formulated and found to improve the accuracy of the EL analysis.

scholarly journals Evaluation on the Soil Flexibility of the Largest HEP Dam Area in East Malaysia using 1-D Equivalent Linear Analysis

2021 ◽  
Vol 11 (4) ◽  
pp. 1535
Author(s):  
Raudhah Ahmadi ◽  
Muhammad Haniz Azahari Muhamad Suhaili ◽  
Imtiyaz Akbar Najar ◽  
Muhammad Azmi Ladi ◽  
Nisa Aqila Bakie ◽  
...  
Keyword(s):  
Linear Analysis ◽  
Equivalent Linear ◽  
East Malaysia ◽  
Soil Flexibility ◽  
Equivalent Linear Analysis

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.

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