Detection and Identification of Bridges Considering Soil Effect

2004 ◽  
Author(s):  
Jun-Ping Pu ◽  
Yao-Min Fang ◽  
Hung-Ren Chen ◽  
Jian-Fa Huang
Keyword(s):  
Soil Structure ◽  
Structural Condition ◽  
Analytical Models ◽  
Dynamic Monitoring ◽  
Structural Monitoring ◽  
Structure Model ◽  
Bridge Inspection ◽  
Inspection Method ◽  
Detection And Identification ◽  
Bridge Structures

Unexpected collapses and near collapse of bridges during the 1999 Chi-Chi earthquake underline the need for effective structural monitoring. Periodic structural condition monitoring of bridge structures is necessary to ensure that they provide a continued and safe service. A systematic study of typical bridges is needed, focusing on identifying elastic analytical models that will incorporate the existing state of bridge. To establish dynamic monitoring as a routine bridge inspection method, the soil-structure model of these two bridges are established and compared theoretically and experimentally.

Numerical and Experimental Assessment of the Highway Arch Viaduct

2015 ◽  
Vol 769 ◽  
pp. 252-259
Author(s):  
Jan Bencat ◽  
Maria Stehlikova ◽  
Milan Skarupa
Keyword(s):  
Dynamic Testing ◽  
Highway Bridges ◽  
Structural Condition ◽  
Traffic Load ◽  
Analytical Models ◽  
Mode Shapes ◽  
Bridge Structure ◽  
Modal Damping ◽  
Bridge Structures ◽  
And Performance

Full–scale dynamic testing of bridge structures can provide valuable information on the service behavior and performance of structures. With the growing interest in the structural condition of highway bridges, dynamic testing can be used as a tool for assessing the integrity of bridges. From the measured dynamic response, induced by instructed passing trucks, modal parameters (natural frequencies, mode shapes and modal damping values) and system parameters (stiffness, mass and damping matrices) are obtained. These identified parameters can then be used to characterize and monitor the service of the bridge structure in the future. Analytical models of the structure can also be validated using these parameters [1,2]. The paper presents a procedure for estimating the traffic load bearing capacity of the steel arch highway viaduct Bridge Structure 205 (DC1–9, 755 m) constructed on Highway D1 in Nord Slovakia (Fig. 1) over the natural hollow basin via dynamic tests of the viaduct structures.

Development of Wire Suspended Robot System (ARANEUS 2.0) for Bridge Inspection

10.29007/zw9k ◽  
2020 ◽  
Author(s):  
Kazuhide Nakata ◽  
Kazuki Umemoto ◽  
Kenji Kaneko ◽  
Ryusuke Fujisawa
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Concrete Surface ◽  
Wire Length ◽  
High Definition ◽  
Bridge Inspection ◽  
Robot System ◽  
Inspection Method ◽  
Aerial Vehicle ◽  
The Wire

This study addresses the development of a robot for inspection of old bridges. By suspending the robot with a wire and controlling the wire length, the movement of the robot is realized. The robot mounts a high-definition camera and aims to detect cracks on the concrete surface of the bridge using this camera. An inspection method using an unmanned aerial vehicle (UAV) has been proposed. Compared to the method using an unmanned aerial vehicle, the wire suspended robot system has the advantage of insensitivity to wind and ability to carry heavy equipments, this makes it possible to install a high-definition camera and a cleaning function to find cracks that are difficult to detect due to dirt.

scholarly journals When did Population III star formation end?

2020 ◽  
Vol 497 (3) ◽  
pp. 2839-2854 ◽  
Author(s):  
Boyuan Liu ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Direct Detection ◽  
Analytical Models ◽  
Space Telescopes ◽  
Detection Rates ◽  
Metal Free ◽  
Detection And Identification ◽  
Future Space ◽  
Study Population ◽  
Population Iii

ABSTRACT We construct a theoretical framework to study Population III (Pop III) star formation in the post-reionization epoch (z ≲ 6) by combining cosmological simulation data with semi-analytical models. We find that due to radiative feedback (i.e. Lyman–Werner and ionizing radiation) massive haloes ($M_{\rm halo}\gtrsim 10^{9}\ \rm M_{\odot }$) are the major (≳90 per cent) hosts for potential Pop III star formation at z ≲ 6, where dense pockets of metal-poor gas may survive to form Pop III stars, under inefficient mixing of metals released by supernovae. Metal mixing is the key process that determines not only when Pop III star formation ends, but also the total mass, MPopIII, of active Pop III stars per host halo, which is a crucial parameter for direct detection and identification of Pop III hosts. Both aspects are still uncertain due to our limited knowledge of metal mixing during structure formation. Current predictions range from early termination at the end of reionization (z ∼ 5) to continuous Pop III star formation extended to z = 0 at a non-negligible rate $\sim \!10^{-7}\ \rm M_{\odot }\ yr^{-1}\ Mpc^{-3}$, with $M_{\rm PopIII}\sim 10^{3}-10^{6}\ \rm M_{\odot }$. This leads to a broad range of redshift limits for direct detection of Pop III hosts, zPopIII ∼ 0.5–12.5, with detection rates $\lesssim 0.1-20\ \rm arcmin^{-2}$, for current and future space telescopes (e.g. HST, WFIRST, and JWST). Our model also predicts that the majority (≳90 per cent) of the cosmic volume is occupied by metal-free gas. Measuring the volume-filling fractions of this metal-free phase can constrain metal-mixing parameters and Pop III star formation.

scholarly journals Motorcycle Structural Fatigue Monitoring Using Smart Wheels

Vehicles ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 648-674
Author(s):  
Federico Ballo ◽  
Francesco Comolli ◽  
Massimiliano Gobbi ◽  
Giampiero Mastinu
Keyword(s):  
Real Time ◽  
Extreme Case ◽  
Time Estimation ◽  
Analytical Models ◽  
Structural Monitoring ◽  
Vertical Force ◽  
Structural Fatigue ◽  
Load Spectra ◽  
Straight Line ◽  
Real Time Estimation

The paper is devoted to the measurement and to the processing of load spectra of forces and moments acting at the wheel hub of a motorcycle. Smart wheels (SWs) have been specifically developed for the scope. Throughout the paper, the extreme case of a race motorcycle is considered. Accurate load spectra were measured in two race circuits. Standardized load spectra are derived by processing measured data. A way to easily generalize the measured load spectra is proposed for the first time for motorcycles. Several loading conditions, related to the motorcycle straight line motion, cornering, curb hit and gear shift, are identified and extracted from the experimental measures. For each loading condition, by means of simple semi-analytical models (SAMs), a relationship is found between the vertical force on the wheel, the tilt angle of the motorcycle and the remaining forces and moments acting at the wheel hub. Such relationships are nothing else than the standardized load spectra. Additionally, a simple and efficient method based on smart wheels for real-time structural monitoring is proposed. Standardized load spectra prove to provide consistent results even when compared to real-time structural monitoring data. By means of the presented smart wheels, advanced lightweight motorcycle construction is enabled by derivation of standardized load spectra or real time estimation of the damage of structural components.

Seismic design of bridge structures with allowance for large relative girder movements to avoid pounding

2009 ◽  
Vol 42 (2) ◽  
pp. 75-85 ◽  
Author(s):  
Nawawi Chouw ◽  
Hong Hao
Keyword(s):  
Ground Motion ◽  
Soil Structure ◽  
Influence Factors ◽  
Bridge Girders ◽  
Gap Size ◽  
Expansion Joint ◽  
Vibration Properties ◽  
Bridge Structures ◽  
Almost All ◽  
Bridge Spans

Pounding between bridge girders have been observed in almost all previous major earthquakes. This is because the gap size of conventional bridge expansion joint is usually only a few centimetres, which is not sufficient to preclude poundings owing to large relative displacements between bridge girders caused by the effect of varying vibration properties of adjacent bridge spans, varying ground motions at bridge supports and varying soil-structure interaction (SSI). In this work a new design of bridge expansion joint is introduced. Instead of tolerating pounding and providing possible mitigating measures, this new design approach enables large movement between bridge girders which makes a complete pounding preclusion possible. The new expansion joint is called Modular Expansion Joint (MEJ). The large movability is achieved by installing a number of small gaps in the joint. In this study, the MEJ gap size required to completely avoid girder pounding is investigated. The most significant influence factors – the varying vibration properties of adjacent bridge spans, the effect of SSI and ground motion spatial variation on expansion joint size required to preclude pounding- are calculated. Discussions on the relative importance of various structural and ground motion properties in generating relative displacements of adjacent bridge girders are made.

Percolation losses in paddy fields with a dynamic soil structure: model development and applications

2010 ◽  
Vol 24 (7) ◽  
pp. 813-824 ◽  
Author(s):  
Manon Janssen ◽  
Bernd Lennartz ◽  
Thomas Wöhling
Keyword(s):  
Soil Structure ◽  
Model Development ◽  
Paddy Fields ◽  
Structure Model
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