scholarly journals AERODYNAMIC STABILITY OF BRIDGES WITH VARIOUS LEVELS OF STRUCTURAL DAMPING

2021 ◽  
Vol 6 (4) ◽  
pp. 54-62
Author(s):  
Olga Poddaeva ◽  
◽  
Pavel Churin ◽  
Keyword(s):  
Experimental Studies ◽  
Real Life ◽  
Wind Tunnels ◽  
Experimental Unit ◽  
State University ◽  
Structural Damping ◽  
Aerodynamic Stability ◽  
Bridge Span ◽  
Bridge Structures ◽  
Girder Bridge

Introduction: Structural damping is one of the most important parameters affecting the aerodynamic stability of bridge structures. Purpose of the study: We aimed to assess the effect that structural damping of a bridge structure has on its stability in a wind current. Methods: In the course of the study, we performed experimental studies of the aerodynamic stability in typical girder bridge structures (with two and four main girders) with different levels of structural damping, facilitated by a unique experimental unit: Large Research Gradient Wind Tunnel, courtesy of the National Research Moscow State University of Civil Engineering (NRU MGSU). Results: The results of the experimental studies show that, despite the general trend towards the decrease in the amplitude of bridge span structure oscillations as the structural damping level increases, the dependence between these parameters is nonlinear. When providing R&D support in the design of real-life structures, in case it is necessary to increase the aerodynamic stability of the superstructure by increasing the level of structural damping (changing the type of joints in structural elements, using mechanical damping devices), it is recommended to conduct experimental studies in wind tunnels to assess the effectiveness of a given solution.

scholarly journals DAMAGE DETECTION OF SHEAR CONNECTORS IN BRIDGE STRUCTURES WITH TRANSMISSIBILITY IN FREQUENCY DOMAIN

2014 ◽  
Vol 14 (02) ◽  
pp. 1350061 ◽  
Author(s):  
JUN LI ◽  
HONG HAO ◽  
YONG XIA ◽  
HONG-PING ZHU
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Concrete Slab ◽  
Experimental Studies ◽  
Measurement Data ◽  
Field Testing ◽  
Damage Level ◽  
Shear Connectors ◽  
Bridge Structures ◽  
Girder Bridge

Shear connectors are generally used to link the slab and girder together in slab-on-girder bridge structures. Damage of shear connectors in such structures will result in shear slippage between the slab and girder, which significantly reduces the load-carrying capacity of bridges. A damage detection approach based on transmissibility in frequency domain is proposed in this paper to identify the damage of shear connectors in slab-on-girder bridge structures with or without reference data from the undamaged structure. The transmissibility, which is an inherent system characteristic, indicates the relationship between two sets of response vectors in frequency domain. Measured input force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at the slab and girder sensor locations by the experimental modal analysis. The transmissibility matrix that relates the slab response to the girder response is then derived. By comparing the transmissibility vectors in undamaged and damaged states, the damage level of shear connectors can be identified. When the measurement data from the undamaged structure are not available, a study with only the measured response data in the damaged state for the condition assessment of shear connectors is also conducted. Numerical and experimental studies on damage detection of shear connectors linking a concrete slab to two steel girders are conducted to validate the accuracy and efficiency of the proposed approach. The results demonstrate that the proposed method can be used to identify shear connector damages accurately and efficiently. The proposed method is also applied to the condition evaluation of shear connectors in a real composite bridge with in-field testing data.

scholarly journals The Influence of Alcohol Consumption on Fighting, Shoplifting and Vandalism in Young Adults

2021 ◽  
Vol 18 (7) ◽  
pp. 3509
Author(s):  
Ieuan Evans ◽  
Jon Heron ◽  
Joseph Murray ◽  
Matthew Hickman ◽  
Gemma Hammerton
Keyword(s):  
Young Adults ◽  
Longitudinal Study ◽  
Alcohol Consumption ◽  
Experimental Studies ◽  
Real Life ◽  
Self Report ◽  
Parents And Children ◽  
Experimental Findings ◽  
Avon Longitudinal Study ◽  
Causal Component

Experimental studies support the conventional belief that people behave more aggressively whilst under the influence of alcohol. To examine how these experimental findings manifest in real life situations, this study uses a method for estimating evidence for causality with observational data—‘situational decomposition’ to examine the association between alcohol consumption and crime in young adults from the Avon Longitudinal Study of Parents and Children. Self-report questionnaires were completed at age 24 years to assess typical alcohol consumption and frequency, participation in fighting, shoplifting and vandalism in the previous year, and whether these crimes were committed under the influence of alcohol. Situational decomposition compares the strength of two associations, (1) the total association between alcohol consumption and crime (sober or intoxicated) versus (2) the association between alcohol consumption and crime committed while sober. There was an association between typical alcohol consumption and total crime for fighting [OR (95% CI): 1.47 (1.29, 1.67)], shoplifting [OR (95% CI): 1.25 (1.12, 1.40)], and vandalism [OR (95% CI): 1.33 (1.12, 1.57)]. The associations for both fighting and shoplifting had a small causal component (with the association for sober crime slightly smaller than the association for total crime). However, the association for vandalism had a larger causal component.

The York-Arup cable experiments: Implications for the fire design of cable-supported bridges

2021 ◽  
Author(s):  
Benjamin Nicoletta ◽  
John Gales ◽  
Panagiotis Kotsovinos
Keyword(s):  
Thermal Strain ◽  
Experimental Studies ◽  
Thermal Response ◽  
Structural Response ◽  
Fire Performance ◽  
Stay Cable ◽  
Stay Cables ◽  
Bridge Structures ◽  
Recent Trends ◽  
High Level

<p>Recent trends towards performance-based fire designs for complex and critical structures have posed questions about the fire resilience of bridge infrastructure. There are little-to-no code requirements for bridge fire resistance and practitioner guidance on the subject is limited. Research on the fire performance of cable-supported bridge structures is scarce and knowledge gaps persist that inhibit more informed fire protection designs in a variety of bridge types. There have been few numerical or experimental studies that investigate the fire performance of steel stay-cables for use in cable-supported bridges. The thermal response of these members is critical as cable systems are highly dependent on the response of individual members, such as in the case of an anchor cable for example. The study herein examines the thermal response of several varieties of unloaded steel- stay cable during exposure to a non-standard methanol pool fire and the implications for the structural response of a cable-supported bridge. Experimental thermal strain data from fire tests of various stay-cables is used to inform high-level insights for the global response of a cable-supported bridge. Namely, the effects of cable thermal expansion on the overall cable system is approximated.</p>

Dynamic Performance Analysis on High-Speed Railway Continuous Girder Bridge

2011 ◽  
Vol 280 ◽  
pp. 186-190
Author(s):  
Shou Tan Song ◽  
Ji Wen Zhang ◽  
Xin Yuan
Keyword(s):  
High Speed ◽  
Moving Load ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Wheel Load ◽  
Dynamic Coefficients ◽  
Bridge Structures ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Dynamic Performance Analysis

The dynamic performance of continuous girder under the train in a series of speed is studied through examples, and the main conclusions are given in the following. The resonance mechanism of continuous girder is similar to simply supported beam. The vehicle wheel load forms regular moving load series, which induces periodical action and resonance of the bridge. The damping ratio of bridge itself has less effect on the amplitude at the loading stage, but significant effects appear when the load departs from the bridge. The count of continuous spans also has less impact on the dynamic coefficients, so three continuous spans can be adopted for calculation and analysis. Span and fundamental frequency have significant influence on dynamic coefficients of bridge structures. To extend the span of the bridge structure can reduce the dynamic coefficient while keeping its frequency invariant. The fundamental frequencies of different bridges are corresponding to certain resonant speeds, which calls for the attention in the design.

scholarly journals How Law Student Prepare Their Life to Survive?

2020 ◽  
Vol 2 (1) ◽  
pp. 19-38
Author(s):  
Aprila Niravita ◽  
Benny Sumardiana ◽  
Bayangsari Wedhatami ◽  
Syukron Salam ◽  
Ubaidillah Kamal ◽  
...  
Keyword(s):  
Character Education ◽  
Real Life ◽  
Field Research ◽  
Law Students ◽  
State University ◽  
Student Activists ◽  
The People ◽  
Law Student ◽  
And Behavior ◽  
Short Time

Character education is an important element in the effort to prepare superior Indonesian human resources, it is of particular concern to be applied especially among students, there is a need for character education because the attitudes and behavior of the people and people of Indonesia now tend to ignore the noble values ​​of Pancasila which are highly respected and should be rooted in everyday attitudes and behaviors, values ​​such as honesty, politeness, togetherness and religious, gradually eroded by foreign cultures that tend to be hedonistic, materialistic, and individualistic, so that the noble character values ​​are ignored in the future if students and young people are not equipped with character education. Law students have their own challenges, especially in the era of globalization. This paper analyzes and illustrates the character strengthening program for law student activists in Semarang State University through several programs, namely public speaking, strengthening student idealism, strengthening advocacy capacitation and human rights assistance and self-motivation. This research is a field research with the object of research as activists of law students who are members of student organizations. This research confirms that the programs for strengthening the character of students experience several obstacles, one of which is the model used and a relatively short time. However, character education for student activists helps students to survive in real life as part of community members.

scholarly journals Simulation Study of the Process of Friction in the Working Elements of a Car Braking System at Different Degrees of Wear

2018 ◽  
Vol 12 (3) ◽  
pp. 221-226 ◽  
Author(s):  
Andrzej Borawski
Keyword(s):  
Simulation Study ◽  
Friction Pair ◽  
Experimental Studies ◽  
Real Life ◽  
Operating Conditions ◽  
Heating Process ◽  
Passenger Cars ◽  
The Road ◽  
Emergency Braking ◽  
Braking System

Abstract Among the many elements of a modern vehicle, the braking system is definitely among the most important ones. Health, and, frequently, life, may rest upon the design and reliability of brakes. The most common friction pair used in passenger cars today is a disc which rotates with the road wheel and a cooperating pair of brake pads. The composite material of the pad results in changing tribological properties as the pad wears, which was demonstrated in experimental studies. The change is also facilitated by the harsh operating conditions of brakes (high and rapid temperature changes, water, etc.). This paper looks into how changing tribology reflects on the heating process of disc and pads during braking. And so a simulation study was conducted, as this method makes it possible to measure temperature in any given point and at any time, which is either impossible or extremely difficult in real life conditions. Finite element method analyses were performed for emergency braking events at various initial speeds of the vehicle reflecting the current road speed limits.

scholarly journals Does Danger Level Affect Bystander Intervention in Real-Life Conflicts? Evidence From CCTV Footage

2021 ◽  
pp. 194855062110426
Author(s):  
Marie Rosenkrantz Lindegaard ◽  
Lasse Suonperä Liebst ◽  
Richard Philpot ◽  
Mark Levine ◽  
Wim Bernasco
Keyword(s):  
Ecological Validity ◽  
Experimental Studies ◽  
Real Life ◽  
Active Role ◽  
Bystander Intervention ◽  
Interpersonal Conflicts ◽  
Ethical Concerns ◽  
Public Surveillance ◽  
Helping Others

In real-life violence, bystanders can take an active role in de-escalating conflict and helping others. Recent meta-analytical evidence of experimental studies suggests that elevated danger levels in conflicts facilitate bystander intervention. However, this finding may lack ecological validity because ethical concerns prohibit exposing participants to potentially harmful situations. Using an ecologically valid method, based on an analysis of 80 interpersonal conflicts unobtrusively recorded by public surveillance cameras, the present study confirms that danger is positively associated with bystander intervention. In the presence of danger, bystanders were 19 times more likely to intervene than in the absence of danger. It extends this knowledge by discovering that incremental changes in the severity level of the danger (low, medium, and high), however, were not associated with bystander intervention. These findings confirm the importance of further investigating the role of danger for bystander intervention, in larger samples, and involving multiple types of real-life emergencies.

Mechanical Behaviour of Steel-Concrete Twin I-Girder Bridges

2018 ◽  
Author(s):  
Weiwei Lin ◽  
Heang Lam ◽  
Teruhiko Yoda
Keyword(s):  
Load Transfer ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Test Results ◽  
Loading Test ◽  
Girder Bridges ◽  
Bridge Model ◽  
Symmetrical Loading ◽  
Unsymmetrical Loading ◽  
Girder Bridge

<p>Steel-concrete composite twin I-girder bridges have been built a lot in both Europe and Japan, but the lack of redundancy has always been a concern in U.S. and many other countries. In addition, few experimental studies have been performed on the mechanical performance of such bridges, particularly for the intact bridges. On this background, a steel-concrete composite twin I-Girder bridge model was designed according to the current highway bridge design specification in Japan and tested in the laboratory. The static loading tests were performed, and two loading conditions including both symmetrical loading and unsymmetrical loading were applied. Load versus deflection relationships were measured in the loading test, and the failure mode of the test specimen was discussed. The flexural strain development on bottom flanges of two main girders was also reported in this paper to confirm the load transfer between two main girders. In addition, the theoretical results on the basis of the classic theory were also provided to compare with the test results. The comparison indicates that the theoretical analyses can predict the behaviour of the twin I-girder bridges very well in the elastic stage by considering the effective width of the slab. The load transfer paths in such bridges were also discussed on the basis of the test results under un-symmetrical loading.</p>

Automation of the technology of connecting parts in the manufacture of aerospace products

2021 ◽  
pp. 24-32
Author(s):  
S. I. Ponomarev
Keyword(s):  
Technological Process ◽  
Computer Aided Design ◽  
Mechanical Engineering ◽  
Experimental Studies ◽  
Diffusion Welding ◽  
Technological Equipment ◽  
State University ◽  
Engineering Technology ◽  
Heat Resistant ◽  
Aided Design

The paper describes the improvement of the technology of manufacturing parts and components of aerospace production using computer-aided design and technological process control. The theoretical foundations and algorithms for constructing the technological process of manufacturing parts and components of the aerospace industry using various methods of joining heat-resistant materials, for example, by diffusion welding, are designed on the basis of theoretical and experimental studies proposed by the author of the patented connection method «Method for joining a heat-resistant cobalt-based alloy with silicon nitride-based ceramics» and technological equipment «Installation for obtaining metal-ceramic products», as well as «Attribute database for creating technological processes for obtaining parts of aerospace production by diffusion welding» and «Attribute database of technological equipment, tools and devices for mechanical processing of aerospace production parts», registered in the register of databases of the Russian Federation. The research is conducted at the Department of Mechanical Engineering Technology of the Institute of Mechanical Engineering and Mechatronics of the Siberian State University of Science and Technology named after academician M.F. Reshetnev.

Robust Output Only Health Monitoring of Steel Railway Bridges

2020 ◽  
pp. 24-41
Author(s):  
Ahmed Rageh ◽  
Daniel Linzell ◽  
Samantha Lopez ◽  
Saeed Eftekhar Azam
Keyword(s):  
Health Monitoring ◽  
Three Dimensional ◽  
Supervised Machine Learning ◽  
Damage Scenario ◽  
Railway Bridges ◽  
Bridge Span ◽  
Structural Responses ◽  
Girder Bridge ◽  
Output Only ◽  
Double Track

This chapter extends application of a framework proposed by the authors (73, 74) for automated damage detection using strain measurements to study feasibility of using sensors that can measure accelerations, tilts, and displacements. The study utilized three-dimensional (3D) finite element models of double track, riveted, steel truss span, and girder bridge span under routine train loads. The chapter also includes three instrumentation schemes for each bridge span (65) to investigate the applicability of the framework to other bridge systems and sensor networks. Connection damage was simulated by reducing rotational spring stiffness at member ends and various responses were extracted for each damage scenario. The methodology utilizes Supervised Machine Learning to automatically determine damage location (DL) and intensity (DI). Simulated experiments showed that DLs and DIs were detected accurately for both spans with various structural responses and using different instrumentation plans.

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