scholarly journals Testing Walking-Induced Vibration of Floors Using Smartphones Recordings

Robotics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 37
Author(s):  
Luca Martinelli ◽  
Vitomir Racic ◽  
Bruno Alberto Dal Lago ◽  
Francesco Foti
Keyword(s):  
Prestressed Concrete ◽  
Concrete Slab ◽  
Modal Testing ◽  
Vibration Monitoring ◽  
Engineering Structures ◽  
Technological Advances ◽  
Accuracy And Precision ◽  
Smartphone Technology ◽  
Structural Engineers ◽  
Experimental Data Collection

Smartphone technology is rapidly evolving, adding sensors of growing accuracy and precision. Structural engineers are among customers who indirectly benefit from such technological advances. This paper tests whether accelerometers installed in new generations of smartphones can reach the accuracy of professional accelerometers created for vibration monitoring of civil engineering structures, and how they can be useful. The paper describes an experimental study designed to measure walking-induced vibrations of a slender prefabricated prestressed concrete slab. Both traditional, high-accuracy, accelerometers and those integrated into commercial smartphones were used for experimental data collection. Direct comparison of the recordings yielded two key findings: the accuracy of smartphone accelerometers largely depends on the specific smartphone model, and nevertheless is satisfactory for preliminary modal testing at the very least. Furthermore, the smartphone measured accelerations of the lower back were used successfully to indirectly measure pedestrian walking loads.

Analisis Forensik Smartphone Android Menggunakan Metode NIST dan Tool MOBILedit Forensic Express

2020 ◽  
Vol 5 (1) ◽  
pp. 89
Author(s):  
Nasirudin Nasirudin ◽  
Sunardi Sunardi ◽  
Imam Riadi
Keyword(s):  
Mobile Device ◽  
Rapid Development ◽  
Rapid Progress ◽  
Data Backup ◽  
Technological Advances ◽  
Smartphone Technology ◽  
Case Simulation ◽  
Device Technology

Technological advances are growing rapidly, including mobile device technology, one of which is an Android smartphone that is experiencing rapid progress with a variety of features so that it can spoil its users, with the rapid development of smartphone technology, many users benefit, but many are disadvantaged by the growing smartphone. technology, so that many perpetrators or persons who commit crimes and seek profits with smartphone facilities. Case simulation by securing Samsung Galaxy A8 brand android smartphone evidence using the MOBILedit forensic express forensic tool with the National Institute of Standards and Technology (NIST) method which consists of four stages of collection, examination, analysis and reporting. The results of testing the Samsung Galaxy A8 android smartphone are carried out with the NIST method and the MOBILedit Forensic Express tool obtained by data backup, extraction and analysis so that there are findings sought for investigation and evidence of crimes committed by persons using android smartphone facilities.

scholarly journals Use of Time- and Frequency-Domain Approaches for Damage Detection in Civil Engineering Structures

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
V. H. Nguyen ◽  
J. Mahowald ◽  
S. Maas ◽  
J.-C. Golinval
Keyword(s):  
Damage Detection ◽  
Frequency Domain ◽  
Prestressed Concrete ◽  
Civil Engineering ◽  
Damage Identification ◽  
Real Life ◽  
Hankel Matrix ◽  
Principal Component ◽  
Engineering Structures ◽  
Civil Engineering Structures

The aim of this paper is to apply both time- and frequency-domain-based approaches on real-life civil engineering structures and to assess their capability for damage detection. The methodology is based on Principal Component Analysis of the Hankel matrix built from output-only measurements and of Frequency Response Functions. Damage detection is performed using the concept of subspace angles between a current (possibly damaged state) and a reference (undamaged) state. The first structure is the Champangshiehl Bridge located in Luxembourg. Several damage levels were intentionally created by cutting a growing number of prestressed tendons and vibration data were acquired by the University of Luxembourg for each damaged state. The second example consists in reinforced and prestressed concrete panels. Successive damages were introduced in the panels by loading heavy weights and by cutting steel wires. The illustrations show different consequences in damage identification by the considered techniques.

scholarly journals Embodied Energy Optimization of Prestressed Concrete Slab Bridge Decks

Technologies ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 43 ◽  
Author(s):  
Julián Alcalá ◽  
Fernando González-Vidosa ◽  
Víctor Yepes ◽  
José Martí
Keyword(s):  
Prestressed Concrete ◽  
Concrete Slab ◽  
Bridge Decks ◽  
Energy Optimization ◽  
Embodied Energy

scholarly journals Long-Term Vibration Monitoring of the Effects of Temperature and Humidity on PC Girders with and without Fly Ash considering ASR Deterioration

2017 ◽  
Vol 2017 ◽  
pp. 1-23
Author(s):  
Tuan Minh Ha ◽  
Saiji Fukada ◽  
Kazuyuki Torii
Keyword(s):  
Fly Ash ◽  
Prestressed Concrete ◽  
Weather Conditions ◽  
Element Model ◽  
Vibration Monitoring ◽  
Mode Shapes ◽  
Numerical Verification ◽  
Evaluation Procedures ◽  
Temperature And Humidity ◽  
Vibration Responses

Structural responses have been used as inputs in the evaluation procedures of civil structures for years. Apart from the degradation of a structure itself, changes in the environmental conditions affect its characteristics. For adequate maintenance, it is necessary to quantify the environment-induced changes and discriminate them from the effects due to damage. This study investigates the variation in the vibration responses of prestressed concrete (PC) girders, which were deteriorated because of the alkali–silica reaction (ASR), concerning ambient temperature and humidity. Three PC girders were exposed to outdoor weather conditions outside the laboratory, one of which had a selected amount of fly ash in its mixture to mitigate the ASR. The girders were periodically vibration tested for one and a half years. It was found that when the temperature and humidity increased, the frequencies and damping ratios decreased in proportion. No apparent variation in the mode shapes could be identified. A finite element model was proposed for numerical verification, the results of which were in good agreement with the measured changes in the natural frequencies. Moreover, the different dynamic performances of the three specimens indicated that the fly ash significantly affected the vibrations of the PC girders under ASR deterioration.

Review of Research on the Seismic Behavior of Integral Prefabricated Prestressed Concrete Slab-Column Structure

2013 ◽  
Vol 831 ◽  
pp. 176-180 ◽  
Author(s):  
Li Li Wu ◽  
Ya Can Cui ◽  
Rong Bin Zhou ◽  
Jia Qing Shi ◽  
Peng He ◽  
...  
Keyword(s):  
Research Methods ◽  
Seismic Performance ◽  
Prestressed Concrete ◽  
Seismic Behavior ◽  
Concrete Slab ◽  
Research Priorities ◽  
Structural System ◽  
Column Structure

The integral prefabricated prestressed concrete slab-column structure was a new structural system introduced to China in 1980s. The structure has a series of obvious advantages and the scholars focus research priorities on its seismic performance. The research methods and developments of seismic behavior of the slab-column structure are summarized, and some measures are also put forward to improve the seismic behavior.

scholarly journals The Experimental Analysis of Vibration Monitoring in System Rotor Dynamic with Validate Results Using Simulation Data

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Hisham A. H. Al-Khazali ◽  
Mohamad R. Askari
Keyword(s):  
Finite Element ◽  
Experimental Analysis ◽  
System Analysis ◽  
Theoretical Data ◽  
Element Model ◽  
Rotating Machinery ◽  
Modal Testing ◽  
Vibration Monitoring ◽  
Mode Shapes ◽  
Computational Techniques

There is a growing tendency today to extract information about the prognostic parameters based on system analysis through various diagnostic techniques to assess the health of the plant or equipment. Vibration monitoring helps in reducing the machine down time. A vibration signature measured at the external surface of machine or at any other suitable place contains a good amount of information to reveal the running condition of the machine. Considering the importance of vibration monitoring in the rotating machinery fault diagnostics, it has been applied in this paper. Effects of modal parameters like natural frequency, mode shapes, and damping, misalignments have been studied. Balancing is usually an expensive and laborious procedure and a balancing system would be beneficial for motor engine and power generation application. In this research, there have been identified unbalance parameters that exist in rotating machinery and develop a finite-element model of rotating dynamics system to create a mathematical model of the system from the test data and subsequently obtaining the unbalanced parameters. During this study, the raw data obtained from the experimental results (Smart Office software) are curve fitted by theoretical data regenerated from simulating it using finite element (ANSYS 12) model for comparisons. The experimental analysis used thus far is called Modal Testing, a well-known and widely used technique in research and industry to obtain the Modal and Dynamic response properties of structures. The technique has recently been applied to rotating structures and some research papers been published, however, the full implementation of Modal Testing in active structures and the implications are not fully understood and are therefore in need of much further and more in-depth investigations. The aim is to find a system identification methodology using the analytical/computational techniques and update the model using experimental techniques already established for passive structures but to active rotating structures, which subsequently help to carry out health monitoring as well as further design and development in rotating machinery.

Experimental Research of Cable in Plate Method

2013 ◽  
Vol 351-352 ◽  
pp. 919-922
Author(s):  
Ping Pang ◽  
Xin Sheng Yin
Keyword(s):  
Theoretical Calculation ◽  
Experimental Research ◽  
Prestressed Concrete ◽  
Calculation Method ◽  
Concrete Slab ◽  
Plate Method

According to the research, a new arrangement method of prestressed concrete slab is provided. It has not been mentioned before and this article discussed unbonded prestressed concrete slab system, and gives the theoretical calculation method.

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