Vertical vehicle displacement based drive-by inspection of bridge damage with parameter optimization

Recently, there has been an increasing emphasis on the Indirect bridge health monitoring method employing passing vehicles, which is regarded as one of the most effective approaches in bridge damage screening. However,few researches have been conducted on the drive-by bridge inspection method using vehicle displacement profile as damage indicator. This paper proposes a new drive-by inspection method based on vertical vehicle displacementprofile with parameter optimization. A generalized Vehicle-Bridge Interaction (VBI) system is built in MATLAB, where the bridge is modelled as a simply supported beam with 10 elements, and the passing vehicle is represented as a simplified quarter car. To improve the result sensitivity to bridge damage, the parameter optimization of vehicle configuration is processed employing the Monte Carlo methods. Results show that the proposed method can successfully detect and localize bridge damage by using vertical vehicle displacement profile as damage indicator only, and its performance may depend on the vehicle configuration. The proposed approach provides merits in simplicity and efficiency, which can be applied widely to the bridge damage detection problems.

Damage identification in steel plate using FRF and inverse analysis

Metaheuristic algorithms have known vast development in recent years. And their applicability in engineering projects is constantly growing; however, their deferent exploration and exploitation techniques cause the engineering problems to favor some algorithms over others. This paper studies damage identification in steel plates using Frequency Response Function (FRF) damage indicator to detect and localize the healthy and damaged structure. The study is formulated as an inverse analysis, investigating the performance of three new metaheuristic algorithms of Wild Horse Optimizer (WHO), Harris Hawks Optimization (HHO), and Arithmetic Optimization Algorithm (AOA). The objective function is based on measured and calculated FRF damage indicators. The results showed that the case of four damages with different damage severity levels presented a good challenge where the HWO algorithm was shown to have the best performance. Both in convergence speed and CPU time.

A Framework for Long-Term Vibration-Based Monitoring of Bridges

A new framework for long-term monitoring of bridges is proposed in order to negate (i) the impact of measurement uncertainties on damage detection in vibration-based structural health monitoring and (ii) the low sensitivity of damage indicators to low levels of damage. The framework is developed using three vibration-based damage indicators that have an intuitive physical correlation with damage: modal curvature, modal strain energy and modal flexibility. The article first quantifies the efficacy of these damage indicators when based on two observations, one from the undamaged state and one from the monitored state, in detecting and locating damage for different damage levels that are simulated on an 84-m long railway bridge. A long-term monitoring framework based on a new parameter defined as the frequency of the damage indicator exceeding the threshold value within a population of observations is developed. Impact of several factors including the damage location, damage indicator used in the framework, and the noise level on the success of the developed framework was investigated through numerical analysis. The new parameter, when used together with modal strain energy, was shown to provide a very clear picture of damage initiation and development over time starting from very low damage levels. Furthermore, the location of the simulated damage can be identified successfully at all damage levels and even for very high noise levels using the proposed framework.

Introduction of a New Parameter to Quantify the Fatigue Damage in Asphalt Mastics and Asphalt Binder

This study involves the quantification of fatigue damage in asphalt materials by introducing a new fatigue damage parameter denoted as the F parameter. One waste filler, i.e., red mud and an asphalt binder were chosen to blend the asphalt mastics at three filler contents of 10, 20, and 30% respectively with respect to the volume of binder and tested at temperatures of 5, 15, and 25 °C. The proposed parameter incorporates the effect of both peak shear stress as well as the failure strain, and hence, can better represent the fatigue damage. A lower value of F is recommended for a better fatigue resistant material. The F parameter was found increasing with the increment in filler content, which signifies higher degree of damage with a high level of stiffening. On the other hand, it consistently decreased with the increment in temperature. The behavior of the materials under the action of increasing shear strain was clearly justified by using the F parameter corresponding to different filler contents and the testing temperatures. In addition to that, the observations from the F parameter were also complemented by the fatigue diagrams. Hence, the proposed parameter is envisaged to be a promising fatigue damage indicator in future works.

Constructing Damage Indices Based on Publicly Available Spatial Data: Exemplified by Earthquakes and Volcanic Eruptions in Indonesia

This article demonstrates the construction of earthquake and volcano damage indices using publicly available remote sensing sources and data on the physical characteristics of events. For earthquakes we use peak ground motion maps in conjunction with building type fragility curves to construct a local damage indicator. For volcanoes we employ volcanic ash data as a proxy for local damages. Both indices are then spatially aggregated by taking local economic exposure into account by assessing nightlight intensity derived from satellite images. We demonstrate the use of these indices with a case study of Indonesia, a country frequently exposed to earthquakes and volcanic eruptions. The results show that the indices capture the areas with the highest damage, and we provide overviews of the modeled aggregated damage for all provinces and districts in Indonesia for the time period 2004 to 2014. The indices were constructed using a combination of software programs—ArcGIS/Python, Matlab, and Stata. We also outline what potential freeware alternatives exist. Finally, for each index we highlight the assumptions and limitations that a potential practitioner needs to be aware of.

Characterization of Contact-Type Defects in Mortar Using a Nonlinear Ultrasonic Method

Second harmonic generation (SHG) is one of the common techniques in the nonlinear ultrasonic test. The contact-type defects play an important role in material damage, which are hard to be detected. The traditional nonlinear parameter β used to evaluate the micro damage in material is derived from the classical stress-strain relation, which is more suitable for the anharmonicity of crystal rather than the contact-type defects. Recently, the theoretical model based on the bilinear stiffness law was derived, and the validity and applicability need to be further studied. For this purpose, by the numerical method, the contact interface in mortar is characterized based on the damage indicator γ. The relation between the excitation voltage and γ is obtained. Moreover, the effects of the crack length and orientation on the damage indicator γ are also obtained. The experimental method is also used to characterize the contact interface in mortar. Combining with the existing work, the results obtained in this article are discussed, and further conclusions can be drawn. The conclusions in this article provide potential of quantitative detection of the contact interface and quality evaluation of bonding layers in materials.

Structural Health Monitoring: An IoT Sensor System for Structural Damage Indicator Evaluation

In the last decades, the applications of structural monitoring are moving toward the field of civil engineering and infrastructures. Nevertheless, if the structures have damages, it does not mean that they have a complete loss of functionality, but rather that the system is no longer in an optimal condition so that, if the damage increases, the structure can collapse. Structural Health Monitoring (SHM), a process for the identification of damage, periodically collects data from suitable sensors that allow to characterize the damage and establishes the health status of the structure. Therefore, this monitoring will provide information on the structure condition, mostly about its integrity, in a short time, and, for infrastructures and civil structures, it is necessary to assess performance and health status. The aim of this work is to design an Internet of Things (IoT) system for Structural Health Monitoring to find possible damages and to see how the structure behaves over time. For this purpose, a customized datalogger and nodes have been designed. The datalogger is able to acquire the data coming from the nodes through RS485 communication and synchronize acquisitions. Furthermore, it has an internal memory to allow for the post-processing of the collected data. The nodes are composed of a digital triaxial accelerometer, a general-purpose microcontroller, and an external memory for storage measures. The microcontroller communicates with an accelerometer, acquires values, and then saves them in the memory. The system has been characterized and the damage indicator has been evaluated on a testing structure. Experimental results show that the estimated damage indicator increases when the structure is perturbed. In the present work, the damage indicator increased by a maximum value of 24.65 when the structure is perturbed by a 2.5 mm engraving.

Multiple load path damage detection with optical fiber Bragg grating sensors

In this article, a new damage indicator is presented that can detect a (partial) load path failure for a multiple load path structure, based on variable amplitude strain response measurements by fiber optic Bragg grating sensors. Many (aircraft) structures have multiple load paths where after a (partial) failure of a load path the remaining structure can carry the limit load without catastrophic failure or too severe impact on the operational characteristics of the whole structure, until the structure is repaired, replaced, or modified. The damage indicator is defined as a ratio of the strain response summation of the current strain time variation measured at fiber Bragg grating (FBG) sensors and a reference strain time variation measured at the same FBGs. For application in real structures with varying loads and environmental conditions, it should be insensitive for the load time variation as well as temperature. The FBG strain response due to a load variation can be easily computed by means of a finite element analyses. In this way, an optimal number, location and orientation of strain sensors can be derived for complex structures. A test was performed on a box-shaped structure representative of a typical aircraft structure to validate the damage indicator, showing that the damage indicator is able to detect a damaged load path at an early stage of failure with few sensors per load path. From finite element analyses, the damage size can even be determined from the damage indicator value for a known damage scenario, making it a level 3 structure health monitoring system.

Markers of myocardial damage after radiofrequency ablation of tachyarrhythmia

<p>This study presents literature data over the past few years on markers of acute myocardial damage after radiofrequency ablation. Information on markers such as troponin I and T, creatine phosphokinase and its fractions, CRP and interleukins and myoglobin is presented in detail. For each potential myocardial damage indicator, data related to their expression site, chemical basis of each marker and correlation between the degree of damage caused by radiofrequency exposure and the levels of various biomarkers of myocardial damage are provided.</p><p>Received 12 November 2019. Revised 26 February 2020. Accepted 27 February 2020.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest</strong>: Authors declare no conflict of interest.</p><p><strong>Author contributions</strong><br />Conception and study design: O.L. Zajfrid, R.B. Tatarsky, E.S. Vasichkina<br />Drafting the article: O.L. Zajfrid, K.A. Chueva, A.V. Mikhailov <br />Critical revision of the article: O.L. Zajfrid, R.B. Tatarsky, E.S. Vasichkina, I.L. Nikitina, D.S. Lebedev<br />Final approval of the version to be published: O.L. Zajfrid, K.A. Chueva, E.S. Vasichkina, A.V. Mikhailov, D.S. Lebedev, I.L. Nikitina, R.B. Tatarsky</p>