Modified Elastic Dynamic Analysis (EDA) for Seismic Demand on In-Span Hinge Shear Keys in Multi-Frame Bridges

2018 ◽  
Vol 2672 (41) ◽  
pp. 75-86 ◽  
Author(s):  
Masoud Mehr ◽  
Arash E. Zaghi
Keyword(s):  
Dynamic Analysis ◽  
High Frequency ◽  
Time History ◽  
Seismic Demand ◽  
Shear Key ◽  
Seismic Force ◽  
Shear Keys ◽  
Modes Of Vibration ◽  
Bridge Models ◽  
High Frequency Modes

Long concrete box-girder bridges are typically constructed in multiple frames that are separated by in-span hinges. Shear keys, located at the in-span hinges, help preserve the transverse integrity of the bridge frames. To date, no reliable method other than nonlinear time history analysis exists to estimate the seismic force demands on in-span shear keys. Methods such as pushover and elastic dynamic analysis (EDA) do not provide accurate estimations. In this study, a rational and reliable analysis method was developed for obtaining the seismic demand on in-span shear keys of multi-frame bridges. A large number of time history analyses were performed on two- to five-frame bridge models with single- and two-column bents that were designed according to California Department of Transportation (Caltrans) Seismic Design Criteria. The results show that high-frequency modes of vibration of the superstructure significantly contribute to the shear key force demands. These modes may also cause transverse yielding in columns. It was established that a modified EDA method may be used to approximate the shear key force demands. In the proposed modified method, the modal forces are reduced separately by the corresponding modal displacement ductility before performing modal combination. This method accounts for the nonlinear response under high-frequency modes of vibration.

scholarly journals Dynamic Analysis of Structure using Fluid Viscous Damper for Various Seismic Intensities

2019 ◽  
Vol 9 (1) ◽  
pp. 517-520
Keyword(s):  
Dynamic Analysis ◽  
Time History ◽  
Viscous Damper ◽  
Base Shear ◽  
Ground Acceleration ◽  
Fluid Viscous Damper ◽  
Rc Structure ◽  
History Analysis ◽  
Seismic Force ◽  
Rc Building

The Dynamic analysis for 5 Storey RC Structure with various seismic intensities are carried out in the present work. SAP 2000 Software considered the structure for modeling. Six ground acceleration for various intensities on MMI Scale to relate seismic response and seismic intensities. In the result, similar variation in storey displacement and base shear with intensities V, VI, VII, VIII, IX and X was witnessed. Through this we can conclude that RC Building using Time History analysis is essential to know if the structure is safe against seismic force or not.

scholarly journals Optimal Seismic Intensity Measure Selection for Isolated Bridges under Pulse-Like Ground Motions

2019 ◽  
Vol 2019 ◽  
pp. 1-22 ◽  
Author(s):  
Linwei Jiang ◽  
Jian Zhong ◽  
Min He ◽  
Wancheng Yuan
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Demand ◽  
Intensity Measure ◽  
Demand Models ◽  
Seismic Force ◽  
Probabilistic Seismic Demand ◽  
Optimal Intensity ◽  
Isolated Bridges

Isolated bridges are commonly designed in the near-fault region to balance excessive displacement and seismic force. Optimal intensity measures (IMs) of probabilistic seismic demand models for isolated bridges subjected to pulse-like ground motions are identified in this study. Four typical isolated girder bridge types with varied pier height (from 4 m to 20 m) are employed to conduct the nonlinear time history analysis. Totally seven structure-independent IMs are considered and compared. Critical engineering demand parameters (EDPs), namely, pier ductility demands and bearing deformation along the longitudinal and transverse directions, are recorded during the process. In general, PGV tends to be the optimal IM for isolated bridges under pulse-like ground motions based on practicality, efficiency, proficiency, and sufficiency criterions. The results can offer effective guidance for the optimal intensity measure selection of the probabilistic seismic demand models (PSDMs) of isolated bridges under pulse-like ground motions.

Numerical Study for Global Detection of Cracks Embedded in Beams

1999 ◽  
Author(s):  
S. A. Lipsey ◽  
Y. W. Kwon
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Natural Frequency ◽  
Mode Shape ◽  
Numerical Study ◽  
Element Model ◽  
Mode Shapes ◽  
Linear Effect ◽  
Modes Of Vibration ◽  
Damage Simulation

Abstract Damage reduces the flexural stiffness of a structure, thereby altering its dynamic response, specifically the natural frequency, damping values, and the mode shapes associated with each natural frequency. Considerable effort has been put into obtaining a correlation between the changes in these parameters and the location and amount of the damage in beam structures. Most numerical research employed elements with reduced beam dimensions or material properties such as modulus of elasticity to simulate damage in the beam. This approach to damage simulation neglects the non-linear effect that a crack has on the different modes of vibration and their corresponding natural frequencies. In this paper, finite element modeling techniques are utilized to directly represent an embedded crack. The results of the dynamic analysis are then compared to the results of the dynamic analysis of the reduced modulus finite element model. Different modal parameters including both mode shape displacement and mode shape curvature are investigated to determine the most sensitive indicator of damage and its location.

Applicability of Modal Pushover Analysis on Bridges

2011 ◽  
Vol 255-260 ◽  
pp. 806-810
Author(s):  
Biao Wei ◽  
Qing Yuan Zeng ◽  
Wei An Liu
Keyword(s):  
Seismic Analysis ◽  
Pushover Analysis ◽  
Time History ◽  
Seismic Demand ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
History Analysis ◽  
Bridge Structures ◽  
Scope Of Application ◽  
Modal Pushover

Taking one irregular continuous bridge as an example, modal pushover analysis (MPA) has been conducted to judge whether it would be applicable for seismic analysis of irregular bridge structures. The bridge’s seismic demand in the transverse direction has been determined through two different methods, inelastic time history analysis (ITHA) and MPA respectively. The comparison between those two results indicates that MPA would be suitable only for bridges under elastic or slightly damaged state. Finally, some modifications are used to improve the MPA’s scope of application, and the results illustrate that the adapted MPA will be able to estimate bridges’ seismic demands to some extent.

Shock Mitigation by Energy Reversal to the High Frequency Modes

2014 ◽  
Author(s):  
Mohammad A. AL-Shudeifat ◽  
Alexander F. Vakakis ◽  
Lawrence A. Bergman
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Computational Study ◽  
Dynamic Structure ◽  
Frequency Mode ◽  
Frame Structure ◽  
Shock Energy ◽  
Modal Damping ◽  
Shock Mitigation ◽  
High Frequency Modes

In this computational study, a light-weight dynamic device is investigated for passive energy reversal from the lowest frequency mode to the high frequency modes of a large-scale frame structure for rapid shock mitigation. The device is based on the single-sided vibro-impact mechanism. It has two functions for passive energy transfer: a nonlinear energy sink (NES) for local energy dissipation and an energy pump to high frequency modes where a significant amount of the shock energy is rapidly dissipated. As a result, a significant portion of the shock energy induced into the linear dynamic structure can be passively reversed from the lowest frequency mode to the high frequency modes and rapidly dissipated by their modal damping. The amount of the energy dissipated by the modal damping of the high frequency modes can be controlled by the amount of inherent damping in the device. Ideally, the device can passively reverse up to 80% of the input shock energy from the lowest frequency mode to the high frequency modes when its damping is assumed to be zero and its impact coefficient of restitution is equal to unity. The shock energy redistribution between this device and the high frequency modes is found to be efficient for rapid shock mitigation in the considered 9-story dynamic structure.

scholarly journals High frequency modes meshfree analysis of Reissner–Mindlin plates

2016 ◽  
Vol 1 (3) ◽  
pp. 400-412 ◽  
Author(s):  
Tinh Quoc Bui ◽  
Duc Hong Doan ◽  
Thom Van Do ◽  
Sohichi Hirose ◽  
Nguyen Dinh Duc
Keyword(s):  
High Frequency ◽  
Meshfree Analysis ◽  
High Frequency Modes

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>

scholarly journals Computational Studies for Comparison between BRB Dampers and SERB New Romanian Dampers Performance in Damping System of High Buildings

2015 ◽  
Vol 13 ◽  
pp. 144-147
Author(s):  
Adriana Ionescu
Keyword(s):  
Dynamic Analysis ◽  
Seismic Analysis ◽  
Computational Study ◽  
Time History ◽  
Computational Studies ◽  
Buckling Restrained Braces ◽  
Software Program

This paper presents a computational study for comparison of the behavior of a ten stories building equipped with two type of damping system: Buckling Restrained Braces (BRB dampers) and SERB new romanian dampers, during romanian earthquakes, according to romanian codes for seismic analysis. This study was computationally finalized using a software program made by the authors which permits time-history dynamic analysis of buildings equipped with different damping devices with different hysteresis such as: Maxwell, Kelvin-Voigt, Zener, Bouc-Wen, Taylor. The study will compare the drifts and the forces applied to the structure by the dampers. The SERB C-194 dampers are a cheaper way to protect the building during earthquake and restrict the drifts similarly with BRB dampers.

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