Study on Simplification Conditions of Curved Regular Bridges under Seismic Effect

2014 ◽  
Vol 580-583 ◽  
pp. 1723-1728
Author(s):  
Tai Yu Song ◽  
Yin Shen ◽  
Guo Ping Li
Keyword(s):  
Seismic Response ◽  
Element Model ◽  
B Value ◽  
Seismic Effect ◽  
Parameter Analysis ◽  
Radius Of Curvature ◽  
R Value ◽  
The Difference ◽  
Girder Bridge ◽  
The Impact

A radius of curvature 20 times greater than the deck width of the bridge (R≥20b) is required as a specification in the regular bridge simplification conditions of the seismic response of curved girder bridges. Selecting benchmark bridges and employing parameter analysis method, this article studies on the effect of R/B value of the curved girder bridge on the response ratio of the seismic response calculated using the finite element model and that using a regular girder bridge. This study shows that on conditions that the deck width of the bridge is constant, the smaller the radius of curvature and the larger the B/R value (i.e., the smaller the R/B value) of the curved girder bridge are, the greater the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is, and the difference is more significant under traverse seismic effect than that of longitudinal seismic effect. On conditions that the radius of curvature is constant, the impact of the change of B/R value due to the deck width change of the bridge on the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is insignificant. Compared with the deck width of the bridge, the difference between the seismic response of the curved girder bridge and the result calculated with a regular girder bridge is more sensitive to the radius of curvature.

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 Influence of Soil Parameters on Detecting Voids behind a Tunnel Lining Using an Impact Echo Method

2019 ◽  
Vol 9 (24) ◽  
pp. 5403
Author(s):  
Meng Ma ◽  
Rongning Cao ◽  
Chao Niu ◽  
Hougui Zhang ◽  
Weining Liu
Keyword(s):  
Element Model ◽  
Tunnel Lining ◽  
Parameter Analysis ◽  
Soil Parameters ◽  
Impact Echo ◽  
Time Frequency ◽  
Box Counting ◽  
Box Counting Dimension ◽  
Frequency Domains ◽  
The Impact

Tunnel lining cavities are a common problem that may affect the bearing capacity of the tunnel-supporting structure, as well as the tunnel service life. The impact echo (IE) method can be used to detect voids behind tunnel linings. For a long tunnel, the surrounding rocks/soils are inhomogeneous and anisotropic, with parameters that vary with tunnel mileages. It is interesting to analyse whether alterations of the soil parameters affect the non-destructive test results. A laboratory experiment was performed in this study, in which voids behind a concrete plate, representing the tunnel lining, were designed to model the ineffective contact between the soil and the tunnel. The IE method was employed to inspect the existence of the void using different signal analysis approaches in the time, frequency and time–frequency domains. Furthermore, the fractal box-counting dimension was calculated for the purpose of quantitative evaluation. Different soil parameters and void sizes were considered, and finally, a finite element model was built and parameter analysis was accomplished using the software ABAQUS. The results demonstrated that: (1) A comprehensive analysis of vibration signals in the time, frequency and time–frequency domains was useful for identifying voids, while the box-counting dimension was useful for evaluating voids quantitatively. (2) Soils with large density and Young’s modulus differences had a certain influence on void detection, while those with large water content and Poisson’s ratio differences had little influence. (3) The box-counting dimension value was stable within the area where the void existed behind the tunnel; when the detection point was beyond twice that of the void dimension, it was difficult to locate the void.

Effect of Radius of Curvature on Seismic Response of Curved Bridge

2011 ◽  
Vol 255-260 ◽  
pp. 1261-1265 ◽  
Author(s):  
Bo Wang ◽  
Yu Xiang Liu
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Response Spectrum ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Curved Bridge ◽  
The Finite Element Analysis ◽  
Calculation Results ◽  
Girder Bridge ◽  
Main Girder

A four span curved HcontinuousH HboxH-girder bridge is used as an engineering example to investigate the effect of radius of curvature on the seismic response of curved bridge. Numerical models with different radii of curvature are created using the finite element analysis program Midas/Civil. The calculation results obtained from response spectrum method show that radius of curvature is an important parameter to curved bridge. When the radius of curvature is large enough, the relationship between seismic response of main girder and radius is approximately linearity, while nonlinear variation is obtained when theradius is not too large. Finally, conclusions are made that seismic design of Hstraight bridgeH unHfoldHed from curved bridge which radius of curvature is specified could Hsatisfy the engineering Hrequirement.

The magneto-seismic method in geoscience

2021 ◽  
Vol 40 (3) ◽  
pp. 194-201
Author(s):  
Qiuzi Li ◽  
Harry W. Deckman ◽  
Deniz Ertaş ◽  
Lang Feng
Keyword(s):  
Magnetic Field ◽  
Seismic Response ◽  
Seismic Waves ◽  
Signal To Noise Ratio ◽  
Cross Product ◽  
Seismic Effect ◽  
Sound Waves ◽  
Current Dipole ◽  
Potential Applications ◽  
The Difference

Key concepts and potential applications associated with a phenomenon hitherto unexplored by the geoscience community, which we have named the magneto-seismic effect, are introduced. The method is based on the simple principle that when an electric charge moves in the presence of an external magnetic field, the charge carrier experiences an instantaneous force, which is equal to the vector cross product of the current it carries and the magnetic field that is present. This “Lorentz force” can create both compressional and shear sound waves in electrical conductors by passing an alternating current through them via an electromagnetic source. In laboratory settings, this magneto-seismic effect can produce readily detectable rock frame displacements. This opens up the possibility of developing new experimental methods to interrogate elastic and poroelastic response of rocks in a broad frequency range from subhertz to megahertz, potentially closing the frequency gap between traditional ultrasonic characterization and properties of interest in the seismic frequency band. In exploration settings, electric current dipole/bipole sources, or novel rotating magnetic dipole sources, can be used to generate electric currents at depth. These currents produce seismic waves at interfaces (or boundaries) where conductivity abruptly changes. The amplitude and propagation directions of these generated seismic waves depend on the relative orientation of the interfaces (or boundaries) with respect to the earth's magnetic field. These seismic waves can then be recorded by receivers at the surface and, in principle, might be processed to yield a resistivity map with seismic resolution. It is shown that processing to obtain a signal from deep targets is significantly limited by seismic background noise. However, an acceptable signal-to-noise ratio might be achieved for shallower targets. The difference between the magneto-seismic response and the previously well-studied electro-seismic response will be discussed.

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.

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.

Analysis for Seismic Responses of Continuous Girder Bridge under Strong Near-Fault Earthquake Level

2013 ◽  
Vol 353-356 ◽  
pp. 1901-1906
Author(s):  
Xin Le Li ◽  
Hui Juan Dou ◽  
Dan Shen
Keyword(s):  
Seismic Response ◽  
Time History ◽  
Element Model ◽  
Near Fault ◽  
Seismic Design Code ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Dynamic Time ◽  
The Finite Element Model ◽  
Force Characteristics

In order to explore the safety performance of continuous structure bridge near fault zone, a typical three spans continuous girder bridge of highway was selected to study the structural seismic response. The finite element model of whole bridge considered the force characteristics of bearing and pile-soil interaction was constructed. Typical near-fault records were selected from the important earthquake events. Several artificial waves characterized with the soil type in bridge site were simulated and used for dynamic analysis. The seismic performance of continuous bridge was studied by nonlinear dynamic time-history method. Research results indicate that, especially large amplitude pulse effect of near-fault records for strong near-fault earthquake, will significantly enhance the seismic response of continuous girder bridge under the second seismic level (EL2) leads to structure to collapse. The fact that the near-fault effect is not considered in China existing highway bridge seismic design code will increase the destructive risk of structure.

scholarly journals Seismic Retrofit of a Multispan Prestressed Concrete Girder Bridge with Friction Pendulum Devices

2018 ◽  
Vol 2018 ◽  
pp. 1-22 ◽  
Author(s):  
Alberto Maria Avossa ◽  
Danilo Di Giacinto ◽  
Pasquale Malangone ◽  
Fabio Rizzo
Keyword(s):  
Seismic Response ◽  
Prestressed Concrete ◽  
Seismic Retrofit ◽  
Nonlinear Behaviour ◽  
Isolation System ◽  
Girder Bridge ◽  
Prestressed Concrete Girder Bridge ◽  
Friction Pendulum ◽  
The Impact ◽  
Concrete Girder

The paper deals with the proposal and application of a procedure for the seismic retrofit of an existing multispan prestressed concrete girder bridge defined explicitly for the use of friction pendulum devices as an isolation system placed between piers top and deck. First, the outcomes of the seismic risk assessment of the existing bridge, performed using an incremental noniterative Nonlinear Static Procedure, based on the Capacity Spectrum Method as well as the Inelastic Demand Response Spectra, are described and discussed. Then, a specific multilevel design process, based on a proper application of the hierarchy of strength considerations and the Direct Displacement-Based Design approach, is adopted to dimension the FPD devices. Furthermore, to assess the impact of the FPD nonlinear behaviour on the bridge seismic response, a device model that reproduces the variation of the normal force and friction coefficient, the bidirectional coupling, and the large deformation effects during nonlinear dynamic analyses was used. Finally, the paper examines the effects of the FPD modelling parameters on the behaviour of the retrofitted bridge and assesses its seismic response with the results pointing out the efficiency of the adopted seismic retrofit solution.

Evaluation of the impact of public investment programs on social and economic performance of territories

2019 ◽  
pp. 109-123
Author(s):  
I. E. Limonov ◽  
M. V. Nesena
Keyword(s):  
Bayesian Modeling ◽  
Positive Impact ◽  
Public Investment ◽  
Difference In Differences ◽  
The Public ◽  
Export Activity ◽  
Regional Investment ◽  
The Difference ◽  
The Impact ◽  
Development Institution

The purpose of this study is to evaluate the impact of public investment programs on the socio-economic development of territories. As a case, the federal target programs for the development of regions and investment programs of the financial development institution — Vnesheconombank, designed to solve the problems of regional development are considered. The impact of the public interventions were evaluated by the “difference in differences” method using Bayesian modeling. The results of the evaluation suggest the positive impact of federal target programs on the total factor productivity of regions and on innovation; and that regional investment programs of Vnesheconombank are improving the export activity. All of the investments considered are likely to have contributed to the reduction of unemployment, but their implementation has been accompanied by an increase in social inequality.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

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