scholarly journals Seismic Vulnerability of Cabinet Facility with Tuned Mass Dampers Subjected to High- and Low-Frequency Earthquakes

2020 ◽  
Vol 10 (14) ◽  
pp. 4850
Author(s):  
Thanh-Tuan Tran ◽  
Anh-Tuan Cao ◽  
Dookie Kim ◽  
Seongkyu Chang
Keyword(s):  
Seismic Response ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Low Frequency ◽  
Element Model ◽  
Mode Shapes ◽  
Collapse Probability ◽  
Numeric Simulation ◽  
Earthquake Frequency ◽  
The Impact

The study investigates the collapse probability of a cabinet facility with a tuned mass damper (TMD) subjected to high- and low-frequency earthquakes. For this aim, a prototype of the cabinet in Korea is utilized for the numeric simulation. The accuracy of the finite element model is evaluated via the impact hammer tests. To mitigate the seismic response of the structure, a TMD system is developed whose properties are designed based on the outcomes from the modal analysis (i.e., modal frequencies and mode shapes). Furthermore, the influences of earthquake frequency contents on the seismic response are evaluated. The numeric analyses are conducted using a series of eighty earthquakes that are classified into two groups corresponding to low- and high-frequency motions. Finally, fragility curves are developed for the cabinet subjected to different ground motion sets. The results quantify the seismic vulnerability of the structure and demonstrate the influences of earthquake frequency contents and the vibration control system on the seismic response of the cabinet.

scholarly journals Seismic Analysis of Connections of Buried Continuous Pipelines

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Wei Liu ◽  
Chunjie Huang ◽  
Yunchang Wang ◽  
Peixin Shi
Keyword(s):  
Seismic Response ◽  
Seismic Analysis ◽  
Element Model ◽  
Continuous Steel ◽  
Influence Coefficient ◽  
Site Class ◽  
Pipeline Networks ◽  
Lifeline Systems ◽  
The Impact ◽  
Gas Supply

Buried pipelines serve as a critical component of lifeline systems, such as water and gas supply. They are interconnected to form a network to transport utilities. The connections change the geometry and stiffness of pipelines and impact the seismic response of the pipelines. This paper investigates the influence of connections on the seismic response of buried continuous steel trunk lines. A finite element model is introduced for analyzing the seismic response of buried pipeline networks. The seismic response of continuous steel pipelines with different connections, including cruciform and T-, K-, L-, and Y-shaped, is analyzed. The impact of site class, pipe diameter, branch angle, and angle of wave incidence on the response of pipe connections is explored. An influence coefficient defined to characterize the strain amplification at the connections is proposed for different forms of connections. Engineering measures to reduce the strain amplification at connections are suggested.

scholarly journals Fragility Assessment of a Container Crane under Seismic Excitation Considering Uplift and Derailment Behavior

2019 ◽  
Vol 9 (21) ◽  
pp. 4660
Author(s):  
Quang Huy Tran ◽  
Jungwon Huh ◽  
Nhu Son Doan ◽  
Van Ha Mac ◽  
Jin-Hee Ahn
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Seismic Excitation ◽  
Damage State ◽  
Limit States ◽  
Container Crane

While the container crane is an important part of daily port operations, it has received little attention in comparison with other infrastructures such as buildings and bridges. Crane collapses owing to earthquakes affect the operation of the port and indirectly impact the economy. This study proposes fragility analyses for various damage levels of a container crane, thus enabling the port owner and partners to better understand the seismic vulnerability presented by container cranes. A large number of nonlinear time-history analyses were applied for a three-dimensional (3D) finite element model to quantify the vulnerability of a Korean case-study container crane considering the uplift and derailment behavior. The uncertainty of the demand and capacity of the crane structures were also considered through random variables, i.e., the elastic modulus of members, ground motion profile, and intensity. The results analyzed in the case of the Korean container crane indicated the probability of exceeding the first uplift with or without derailment before the crane reached the structure’s limit states. This implies that under low seismic excitation, the crane may be derailed without any structural damage. However, when the crane reaches the minor damage state, this condition is always coupled with a certain probability of uplift with or without derailment. Furthermore, this study proposes fragility curves developed for different structural periods to enable port stakeholders to assess the risk of their container crane.

scholarly journals Effect of Aftershock Characteristics on the Fragility Curve of Post-Mainshock RC Frames

2021 ◽  
Author(s):  
Ali Massumi ◽  
Kabir Sadeghi ◽  
Omid Ghojoghi
Keyword(s):  
Fragility Curves ◽  
Significant Duration ◽  
Rc Frames ◽  
Collapse Probability ◽  
Site Characteristics ◽  
Wide Range ◽  
Seismic Records ◽  
Earthquake Sequences ◽  
The Impact ◽  
Selection Of

Abstract Buildings constructed in seismic zones are not only damaged by mainshocks but may also be damaged by the impact of aftershocks and cause them to collapse. Therefore, studying the behavior of the damaged structures due to the mainshock and aftershock helps in post-mainshock decision making and also in the selection of suitable aftershock records for seismic assessing of the structure under earthquake sequences. This paper presents the effects of aftershock ground motion on the collapse capacity of post-mainshock buildings. The mean period (Tm), predominant velocity period (Tg), frequency bandwidth (Ω), the 5%-95% significant duration (Ds) and seismic records of different sites were selected to evaluate the effect of its characteristics on the collapse capacity of buildings. The intensity of the ground motions was determined by the first-mode spectral acceleration with 5% damping. Collapse capacities of two non-ductile reinforced concrete (RC) frames with 3 and 6 stories were evaluated using a set of 62 aftershock records with a wide range of characteristics. Box plot collapse diagrams and fragility curves have been developed by applying the incremental dynamic analysis (IDA). The results show that in the frequency content with a longer period, the probability of its collapse is higher. In addition, the high significant duration of aftershocks increases the collapse probability of structures. Also, the evaluation of the site characteristics shows differences in collapse capacities of the same frames in varying sites. Therefore, the effect of aftershock characteristics on the capacity of the structures is significant and it is necessary to carefully determine the seismic sequences’ recordings for the evaluation of the seismic behavior of the structures.

scholarly journals Fragility Assessment of Container Crane under Seismic Excitation Considering Uplift and Derailment Behavior

2019 ◽  
Author(s):  
Quang Huy Tran ◽  
Jungwon Huh ◽  
Nhu Son Doan ◽  
Van Ha Mac ◽  
Jin-Hee Ahn
Keyword(s):  
Structural Damage ◽  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Three Dimensional ◽  
Time History ◽  
Element Model ◽  
Seismic Excitation ◽  
Damage State ◽  
Limit States ◽  
Container Crane

While the container crane is an important part of daily port operations, it has received little attention compared with other infrastructures, such as buildings and bridges. Crane collapse due to earthquake affects the operation of the port, and indirectly impacts the economy. This study proposes fragility analyses for various damage levels of the container crane that allow the port owner and partners to better understand the seismic vulnerability presented by container cranes. A large quantity of nonlinear time history analyses was applied for a three-dimensional (3D) finite element model to quantify the vulnerability of the container crane in considering the uplift and derailment behavior. The uncertainty of demand and capacity of the crane structures were also considered through random variables, i.e. elastic modulus of members, ground motion profile, and intensity. The results analyzed in the case of a Korean container crane showed that the probability of exceeding the first uplift with or without derailment is shown before the crane reaches the structure’s limit states. This means that under low seismic excitation, the crane might be derailed without any structural damage. But when the crane reaches the minor damage state, it is always coupled with a certain probability of uplift with or without derailment. This study also proposes the fragility curves developed for different structural periods to enable port stakeholders to assess the risk of their container crane.

Study on Looseness and Impact - Rub Coupling Faults of a Vertical Dual-Disk Cantilever Rotor- Bearing System

2007 ◽  
Vol 353-358 ◽  
pp. 2479-2482
Author(s):  
Yan Jun Lu ◽  
Zhao Hui Ren ◽  
Hong Chen ◽  
Nai Hui Song ◽  
Bang Chun Wen
Keyword(s):  
Finite Element ◽  
Low Frequency ◽  
Element Model ◽  
Coupling Faults ◽  
Mechanics Model ◽  
Low Frequency Vibration ◽  
Rotor Bearing ◽  
Impact And Rubbing ◽  
The Impact ◽  
Bearing System

Because of wrong setting or long-term running of rotating machinery, the looseness may ouur in the bearing seats or bases. And also bring impact and rubbing of rotor-stator, That is the looseness and rub-impact coupling fault. In the paper,a mechanics model and a finite element model of a vertical dual-disk cantilever rotor- bearing system with coupling faults of looseness and rub-impact are set up. Based on the nonlinear finite element method and contact theory, the dynamical characteristices of the system under the influence of the looseness rigidity and impact-rub clearance is studied. The results show that the impact-rub of rotor-stator can reduce the low frequency vibration caused by looseness, and the impact-rub caused by looseness has obvious orientation. Also, the conclusion of diagnosing the looseness and rub-impact coupling faults is given in the end of the paper.

Effect of Soil on the Seismic Response of Structures Taking Into Consideration Soil-Structure Interaction

2020 ◽  
Vol 11 (2) ◽  
pp. 72-90
Author(s):  
Radhwane Boulkhiout ◽  
Salah Messast
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Shear Walls ◽  
Element Model ◽  
Soil Structure Interaction ◽  
Reinforced Concrete Frame ◽  
Structure Interaction ◽  
Model Soil ◽  
The Impact

The present study covers the influence of soil-structure interaction on the response of structures and civil engineering constructions under seismic excitation. The response of the structures being studied was evaluated, first, using a perfectly embedded structure at the base. Then, using two different models to model soil-structure contact, the finite element model and a rheological model (springs and dampers) in order to illustrate the impact of soil type behavior on structure response was considered based on periods, displacements, and stresses. On the other hand, the effect of superstructure type and its stiffness on the seismic response will be determined, first, using a reinforced concrete frame with shear walls and, second, using a girder bridge. Finally, in each model mentioned above, a parametric study was conducted to better understand the dynamic behavior of the analyzed structure. As for modelling by finite element method, the study was achieved using SAP2000 code.

Analysis of Unimorph Piezoceramic Patches on Damped Square Shaped Plate

2013 ◽  
Vol 315 ◽  
pp. 965-971 ◽  
Author(s):  
A.M. Najib ◽  
A.J. Fairul ◽  
Ahmad Yusairi Bani Hashim ◽  
Hazman Hasib ◽  
M.N. Muhammad
Keyword(s):  
Low Frequency ◽  
Piezoelectric Element ◽  
Element Model ◽  
Mode Shapes ◽  
Vibration Displacement ◽  
Electric Excitation ◽  
Damping Control ◽  
Linear Behavior ◽  
Vibration Problems ◽  
Force Excitation

Active damping using piezoelectric element is one of the effective techniques to counter vibration problems. A 3D finite-element model is developed as part of investigation for damping control. The piezoelectric patches are surface bonded on quadrilateral thin plate and supported with spring damper elements. The main goal of this paper is to investigate mechanical characteristics of piezoceramic array on membrane and the effect of force excitation using small motor and electric excitation on the system. The system setup produced small vibration displacement and does not displace the plate beyond elastic strain region. The results show the linear behavior of piezoceramic and the correlation between electric excitation, motor vibration and displacement at the centre of the plate at different frequency range. The mode shapes and natural frequencies at low frequency spectrum are also presented. Therefore, the results can be used as reference to develop damping system with aid of piezoelectric patches.

scholarly journals Seismic vulnerability assessment and fragility curves for a multistorey gallery arch bridge

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Vinay Shimpi ◽  
Madappa V. R. Sivasubramanian ◽  
S. B. Singh ◽  
D. Kesavan Periyasamy
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Nonlinear Dynamic Analysis ◽  
Ambient Vibration ◽  
Stone Masonry ◽  
Mode Shapes ◽  
Fe Model ◽  
Masonry Arch ◽  
Arch Bridge ◽  
Railway Line

AbstractThe masonry bridges on the Kalka Shimla Mountain Railway line, which have multiple arch galleries in the form of Roman aqueducts, are spectacular. The Kalka Shimla Mountain Railway line is situated in severe seismic zones (Indian Standard 1893:2016). This research assesses the seismic vulnerability of masonry arch Bridge No. 541 situated on the Kalka Shimla Mountain Railway line. This bridge is the tallest on the route. In particular, it assesses the seismic vulnerability of the bridge using finite element (FE) analysis. For this purpose, an FE model for the bridge is developed using the ABAQUS FE-based environment. The experimental field study conducted on the bridge using an ambient vibration test (AVT) and dynamic parameters (frequency and mode shapes) is evaluated by operational modal analysis (OMA). Further, the FE model is updated by modifying the elastic mechanical property of the stone masonry to match the analytical modal frequency with the results of the AVT and OMA. The updated model is then used to perform a pushover analysis and nonlinear dynamic analysis to estimate the seismic performance of the bridge. Furthermore, fragility curves are developed for the bridge to estimate the damage state for specific seismicity. The study shows that the bridge is vulnerable to Zone IV seismicity and needs some retrofitting in specific locations such as the pier–abutment joints.

Experimental Study on Complex Modes of an End Damped Continuous Beam

2015 ◽  
Author(s):  
Xing Xing ◽  
Brian F. Feeny
Keyword(s):  
Damping Ratio ◽  
Continuous System ◽  
Element Model ◽  
Damping Coefficient ◽  
Mode Shapes ◽  
Modal Damping ◽  
Complex Modes ◽  
Cantilevered Beam ◽  
Eddy Current Damper ◽  
The Impact

The complex modes of an end-damped cantilevered beam are studied as an experimental example of a non-modally damped continuous system. An eddy-current damper was applied considering its noncontact and linear properties. The state-variable modal decomposition (SVMD) is applied to extract the modes from the impact responses in the cantilevered beam experiments. Characteristics of the mode shapes and modal damping are examined for various values of the damping coefficient. The modal frequencies and mode shapes obtained from the experiments have a good consistency with the results of the finite-element model. The variation of damping ratio and modal nonsynchronicity with varying damping coefficient also follow the prediction of the model. Over the range of damping coefficients studied in the experiments, we observe a maximum damping ratio in the lowest underdamped mode, which correlates with the maximum modal nonsynchronicity. Complex orthogonal decomposition (COD) is applied in comparison to the modal idenfication results obtained from SVMD.

Finite Element Modelling of a Generic Rotor-Bearing System and Experimental Validation

2015 ◽  
Author(s):  
A. Rehman ◽  
K. S. Ahmed ◽  
F. A. Umrani ◽  
B. Munir ◽  
A. Mehboob ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Element Model ◽  
Mode Shapes ◽  
Efficient Operation ◽  
Critical Speeds ◽  
Rotor Bearing ◽  
The Impact ◽  
Bearing System

The design and development of the rotating machinery require a precise identification of its dynamic response for efficient operation and failure prevention. Determination of critical speeds and mode shapes is crucial in this regard. In this paper, a finite element model (FEM) based on the Euler beam theory is developed for investigating the dynamic behavior of flexible rotors. In-house code in Scilab environment, an open source platform, is developed to solve the matrix equation of motion of the rotor-bearing system. The finite element model is validated by the impact hammer test and the dynamic testing performed on the rotors supported on a purpose-built experimental setup. Bearing stiffness is approximated by using the Hertzian contact theory. Obtaining the critical speeds and mode shapes further improves the understanding of dynamic response of rotors. This study paves way towards advanced research in rotordynamics in Faculty of Mechanical Engineering, GIK Institute.

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