Damage Evaluation Method Research Articles

Detection and Damage Evaluation of Hinge Joints in Hollow Slab Bridges Based on a Light-Load Field Test

The hollow slab bridge is a widely used bridge type for urban bridges. The slabs are prefabricated in a factory and are assembled on site, and then the hinge joints are poured on site. Shallow hinge joints have been used in most existing hollow slab bridges, which commonly bring inadequate connection to the adjacent slabs and probably result in bridge damage. Traditional detection and test methods for hinge joints interrupt traffic, which is inconvenient for local commuters. In the present study, a light-load field test method for hinge joints was proposed. The principles and procedures of the light-load test were concluded and provided based on the test results of 96 spans. The theoretical and measured lateral load distribution ratios were calculated and compared based on hinge joint plate theory. The damage evaluation method and damage classification for hinge joints were defined based on the test results of 1100 hinge joints. Furthermore, the accuracy of the proposed method was verified by a destructive experiment. The research results indicate that the light-load field test and the damage evaluation method for hinge joints are indeed convenient, reliable, and economical, and deserve practical spread and repetition in this area.

A review on the drilling of CFRP/Ti stacks: Machining characteristics, damage mechanisms and suppression strategies at stack interface

Carbon fiber reinforced polymer (CFRP)/titanium alloy (Ti) stacks have promising application in aerospace field due to their excellent mechanical properties. During integrated drilling of CFRP/Ti stacks, the machining process at interface between CFRP and titanium alloy is very complicated. The interaction among CFRP, titanium alloy and cutting tool leads to poor processing quality, serious tool wear and other problems. In this paper, in order to deeply analyze the influence mechanism of interface area on the machining process, the research achievements and progress of drilling CFRP/Ti stacks are reviewed. Special attention is paid to the machining characteristics and CFRP damage mechanism at stack interface during drilling and helical milling of CFRP/Ti stacks. The cutting force characteristics, temperature characteristics and tool wear characteristics of interface machining are analyzed, and the damage mechanism and evaluation method are summarized. In order to solve the existing problems in drilling CFRP/Ti stacks, the suppression strategies of interface damage in recent years are discussed from four aspects: machining parameters, machining environment, tool structure and advanced machining technology. The research trend of laminated interface machining is prospected, which provides an important reference value for the realization of precision, high efficiency and low damage integrated drilling of CFRP/Ti stacks.

Application of elastic wave tomography method for damage evaluation in a large-scale reinforced concrete structure

Quality control of construction works and characterization of defects in newly built reinforced concrete structures is an important issue. Usually, these kinds of defects can be evaluated by means of visual inspection, however, there are cases, in which damage cannot be reliably evaluated visually. In this situation, Non-Destructive Testing methods can be used. In this study we report the results of application of Elastic Wave Tomography method for evaluation of a defect in a newly built reinforced concrete bridge pier. A large void located inside the bridge pier was detected using Elastic Wave Tomography method. Due to the presence of the large defect the structure was demolished. Elements of the demolished bridge pier were visually observed, which allowed to confirm the results of Elastic Wave Tomography method.

Subsection and superposition method for reservoir formation damage evaluation of complex-structure wells

Kinds of complex-structure wells can effectively improve production, which are widely used. However, in the process of drilling and completion, complex-structure wells with long drilling cycle and large exposed area of reservoir can lead to the fact that reservoir near wellbore is more vulnerable to the working fluid invasion, resulting in more serious formation damage. In order to quantitatively describe the reservoir formation damage in the construction of complex-structure well, taking the inclined well section as the research object, the coordinate transformation method and conformal transformation method are given according to the flow characteristics of reservoir near wellbore in anisotropic reservoir. Then the local skin factor in orthogonal plane of wellbore is deduced. Considering the uneven distribution of local skin factor along the wellbore, the oscillation decreasing model and empirical equation model of damage zone radius distribution along the wellbore direction are established and then the total skin factor model of the whole well is superimposed to realize the reservoir damage evaluation of complex-structure wells. Combining the skin factor model with the production model, the production of complex-structure wells can be predicted more accurately. The two field application cases show that the accuracy of the model can be more than 90%, which can also fully reflect the invasion characteristics of drilling and completion fluid in any well section of complex-structure wells in anisotropic reservoir, so as to further provide guidance for the scientific establishment of reservoir production system.

Influence of Hydrodynamic Pore Pressure Damage on the Performance of Hot-Mixed Renewable Asphalt Mixture

For evaluating the water stability of hot-mixed renewable asphalt mixture (HRM), the traditional methods are all tested under still water conditions. Except for damage in still water conditions, the hydrodynamic pore pressure generated by the tire driving on the surface water has a great impact. Thus, the RAP contents of the HRMs were designed at 0%, 30%, 45% and 60% with AC-25 gradation. Then, the self-designed evaluation methods of water stability and dynamic modulus were studied. Finally, the mechanism of the influence of hydrodynamic pore pressure damage on HRMs was studied. The results show that the water stability of HRM containing 30% RAP is equivalent to that of 45% RAP, and the water stability of HRM containing 60% RAP decreases significantly. The Contabro test after MIST treatment can be used as an evaluation method for hydrodynamic pore pressure damage on HRM. Low-speed, heavy-load traffic and larger RAP content have greater damage to the mixture after hydrodynamic pore pressure damage. The performance differences between the aged bitumen and pure bitumen, as well as the aged minerals and new minerals, are continuing to be enlarged in hydrodynamic pore pressure conditions, finally affecting the water stability and dynamic modulus of the HRMs.

Experimental study on scabbing limit of local damage to reinforced concrete panels subjected to oblique impact by projectile with semispherical nose

The influence evaluation against projectile impacts has attracted much attention for the safety assessment of nuclear-facility buildings subjected to projectiles, such as tornado missiles or aircraft. Many experimental studies have been reported on the impact resistance of reinforced concrete (RC) structures. Based on these results, many empirical formulas for penetration depth, scabbing limit thickness, and perforation-limit thickness have been proposed for the local damage evaluation. However, most formulas were derived from impact tests based on normal impact to target structures using rigid projectiles that do not deform during impact. Therefore, this study develops a local damage evaluation method considering the rigidity of projectiles and oblique impacts that should be considered in realistic projectile impact phenomena. Specifically, we focused on scabbing, defined as the peeling off the back face of the target opposite the impact face, and conducted impact tests on RC panels to clarify the scabbing limit by changing the impact velocity in an oblique impact. The effects of the projectile rigidity and oblique impact on the scabbing limit were investigated based on the test results. This work presents the test conditions, equipment, results, and the scabbing limit on the local damage to RC panels subjected to oblique impacts.

A Novel Parameter for Fatigue Damage Assessment of Laser-Repaired Nickel-Based Alloy.

The fatigue damage assessment of laser-repaired components is critical to their service safety. However, since laser repairing is an advanced green remanufacturing technology, the current research on its fatigue mechanical behavior and fatigue damage evaluation methods is still immature. In addition, the relevant models used for the fatigue damage evaluation can only indicate the fatigue limit of components, which cannot describe the damage accumulation process of the components during the fatigue testing. Therefore, there is an urgent need to develop a fatigue damage evaluation method that can describe the fatigue damage accumulation and evolution to reveal the damage evolution mechanism during the fatigue test. In this study, based on the 3D-DIC technique, new damage parameters, i.e., strain average value and strain standard deviation, are proposed to quantitatively describe the damage status of the nickel-based components during the stress-based fatigue process. Then, based on the new damage parameters, a strain average value/strain standard deviation damage curve method is proposed to describe the damage status evolution of the components during the fatigue testing and evaluate its fatigue damage. For example, in the tensile fatigue test, the strain average value/strain standard deviation damage curves of the substrate component and the laser-repaired component can be divided into two damage stages. In the first damage stage, the damage increases slowly with the increase in the cycle number, whereas in the second damage stage, the damage increases rapidly with the increase in the cycle number. At this time, there is a demarcation point between the first damage stage and second damage stage in the strain average value damage curve and strain standard deviation damage curve. The cycle number of the demarcation point can be used as a reference value for the fatigue failure of the laser-repaired component. In addition, the electron backscatter diffraction (EBSD) technique was used to verify the validity of the evaluation results from the novel damage parameters.

A Surface Crack Damage Evaluation Method Based on Kernel Density Estimation for UAV Images

The development of UAV (unmanned aerial vehicle) technology provides an ideal data source for the information extraction of surface cracks, which can be used for efficient, fast, and easy access to surface damage in mining areas. Understanding how to effectively assess the degree of development of surface cracks is a prerequisite for the reasonable development of crack management measures. However, there are still no studies that have carried out a reasonable assessment of the damage level of cracks. Given this, this article proposes a surface crack damage evaluation method based on kernel density estimation for UAV images. Firstly, the surface crack information from the UAV images is quickly and efficiently obtained based on a machine learning method, and the kernel density estimation method is used to calculate the crack density. The crack nuclear density is then used as a grading index to classify the damage degree of the study area into three levels: light damage, moderate damage, and severe damage. It is found that the proposed method can effectively extract the surface crack information in the study area with an accuracy of 0.89. The estimated bandwidth of the crack kernel density was determined to be 3 m based on existing studies on the effects of surface cracks on soil physicochemical properties and vegetation. The maximum crack density value in the study area was 316.956. The surface damage area due to cracks was 14376.75 m2. The damage grading criteria for surface cracks in the study area (light: 0–60; moderate: 60–150; severe: >150) were determined based on the samples selected from the field survey by crack management experts. The percentages of light, moderate, and severe damage areas were 72.77%, 23.22%, and 4.01%, respectively. The method proposed in this article can effectively realize the graded damage evaluation of surface cracks and provide effective data support for the management of surface cracks in mining areas.

Application of the Deformation Behavior Evaluation Method for the Quick Inspection of U-Shaped Steel Dampers

ABSTRACT Practical cumulative damage evaluation methods are essential for commercializing metallic dampers, such as U-shaped steel dampers. The high dependence on numerical simulations, such as time-history analysis, significantly restricts the use of the previously reported cumulative damage evaluation method in the quick inspection of U-shaped steel dampers. This makes simplifying and efficiently certifying the estimated value of cumulative damage difficult. Therefore, the precision verification approach of the previously reported damage evaluation method and quick inspection method are combined in this study based on the change in the shape of the dampers caused by dynamic cyclic loading.

Influence of accelerated chloride corrosion on mechanical properties of sea sand ECC and damage evaluation method based on nondestructive testing

Sea-sand engineered cementitious composite (SECC) is a new version of engineered cementitious composite for marine constructions that face the scarcity of river/manufactured sand. This study explores the effect of chloride corrosion on the mechanical properties of SECC with polyethylene fibers (PE/SECC) and polyvinyl alcohol fiber-reinforced sea-sand engineered cementitious composite (PVA/SECC), which are critical for its applications in marine engineering. The accelerated chloride corrosion test (dry-wet cycling/soaking), rapid chloride migration (RCM) test, and dry shrinkage test were conducted. In addition, the thickness of the damaged layer and changes in relative dynamic modulus of elasticity (RDME) of SECCs were analyzed by ultrasonic nondestructive testing. The results revealed that the chloride corrosion did not produce a significant effect on the compressive strength and RDME of SECCs. Furthermore, the drying shrinkage of SECCs and accumulation of Friedel's salt induced swelling stress inside the SECC. Under the corrosion action of chloride, a number of microcracks appeared on the surface of the polyethylene (PE) fibers, making the PE/SECC less ductile. For the purpose of assessing the damage to the SECC, a computing formula was proposed based on the damage degree, RDME, relative mass, and resistance to chloride ion penetration under the coupling effect of chloride corrosion, and dry-wet cycling or soaking. Using the formula, the obtained critical values for the dry-wet cycling and soaking system were γCN = 20.74 and γSN = 21.36, respectively. The research results promote the application of SECCs in practical engineering, and provides beneficial guidance for the design and application of SECCs in offshore structures, improving the chloride corrosion resistance of offshore structures.

DAMAGE EVALUATION ON STEEL MEMBERS SUBJECTED TO SEISMIC RESPONSE USING THERMOELECTRIC DEVICES WITH FREQUENCY DEPENDENCY

After the earthquake events, building damage assessment is detected by experts. However, in fact, it takes a long time to conduct the assessment process during field survey. Also, it is worried about ensuring the safety of the surveys. In recent years, structural health monitoring has been attempted. This paper suggests a damage evaluation method based on temperature measurement using thermoelectric devices. The cyclic loading tests were conducted as parameters with the loading amplitude; three types of constant amplitude, and three types of variable amplitude with gradual decrease, gradual increase, and random amplitude, totaling six types of dynamic cyclic bending. As a result of applying the damage evaluation method to the loading test, it was confirmed that the cumulative damage calculated from the temperature measurement and the cumulative damage calculated from the input displacement were almost equal. In addition, seismic response analysis was conducted using an analytical model of a four-story building, and the effectiveness of the measurement method using thermoelectric devices was examined. The results of seismic response analysis shows that the natural frequency of the primary mode of the displacement response was lower than 4Hz, and the results of the sweep loading test confirmed that the thermoelectric devices captured the waveform of the temperature up to 4Hz.

DAMAGE EVALUATION METHOD OF STEEL DAMPERS SUBJECTED TO SEISMIC RESPONSE BEHAVIOR BY USING MICROCOMPUTER

After the severe seismic disaster, to investigate the damage states of buildings, the experts go to the disaster area, however, they encounter some difficulties. To solve the above problems, this study suggests a damage evaluation system for steel structures, which adopts the concept of Internet of Things (IoT). This system makes it possible for us to hold on damage of a building without going there after an earthquake. It has been recognized that the temperature change occurs on steel materials during inelastic behavior. In other study, the effectiveness of the damage evaluation method was confirmed by using the heat generation of steel at unsteady plastic amplitude. Here, the experimental study and discuss is performed to investigate the effectivity of evaluation method with the history of voltage by thermoelectric devices measured by a microcomputer when subjected to seismic response behavior. The cumulative plastic strain can be estimated from the relationship between temperature and strain of steel using the inverse heat conduction analysis. By dividing the cumulative plastic strain into half cycles, the strain amplitude per half cycle can be estimated, and the degree of damage can be calculated from the strain amplitude. By conducting the above analysis, we could predict damage level of the steel from the history of voltage by thermoelectric devices under the seismic response behavior. In addition, it was also shown that the microcomputer can be used to track the temperature rise of plastic heating in steel.

Structural monitoring method for RC column with distributed self-sensing BFRP bars

Reinforced concrete (RC) columns may be damaged under earthquakes or wind loads, which will severely affect their bearing capacity. Current damage evaluation methods are mainly based on displacement measurement, which makes evaluating local structural damage difficult. Therefore, this study proposes an RC column structural monitoring and evaluation method based on a distributed self-sensing basalt fiber reinforced polymer (BFRP) bar with optical fiber sensors inside. First, the self-sensing BFRP bar is introduced, including the sensing principle, inner structure, and basic sensing performance. It is found that the strain sensing coefficient of the proposed self-sensing BFRP bar presents only 2.2 % difference from that of the bare optical fiber sensor, meaning the BFRP package take no negative effect on the strain sensitivity. Second, the analytical methods of curvature and displacement are established based on the strain distribution measurement, in which the influence of bond-slip on parameter calculations is mainly considered. Finally, the proposed method was well verified by the loading tests of one RC column with self-sensing BFRP bars. Among the results, the absolute displacement measurement error increase with the development of structure damage, which can be even up to several mm after the steel yielding. However, the relative displacement measurement error can be still controlled within 20 % until the structure failure of the RC column. Considering the additional long-term performance of the proposed self-sensing BFRP bar, the proposed method is expected to implement long-term monitoring of RC columns.

Damage Evaluation Method for Steel Beams Subjected to Cyclic Loading

Damage Evaluation Method for Steel Beams Subjected to Cyclic Loading

Hysteretic behavior degeneration mechanism and damage evaluation of self-centering bridge pier system

Damage often occurs in the contact segment of self-centering (SC) bridge pier systems and significantly affects their hysteretic behavior under cyclic loading or seismic excitations. To quantify the degree of decline of the mechanical indices in the damaged SC bridge pier system, this study investigated the degeneration mechanism of the SC bridge pier system and its damage evaluation method. First, two damage modes, the resilient damage (RD) and brittle damage (BD) modes, are innovatively defined. Subsequently, the backward movement mechanism of the rotation point in the SC bridge pier system was investigated in detail, and the corresponding degradation mechanism of hysteretic behavior was specified in terms of experimental observation and mechanical analysis. Then, the application of hysteretic degradation mechanism was presented, and its correctness was verified using experimental data. Finally, a novel damage index (DI) specific to the SC bridge pier system, which can reasonably reflect key mechanical properties such as stiffness, yield carrying capacity, carrying capacity, and residual drift, is proposed and compared with existing DIs in terms of principle and evaluation effects. The results confirm that the proposed DI model can accurately evaluate the damage state of the SC bridge pier system.

Water Blocking Damage Evaluation and Mitigation Method in Tight Gas Reservoirs

Water Blocking Damage Evaluation and Mitigation Method in Tight Gas Reservoirs

Numerical Analysis Method for Liquefaction-induced Damage Evaluation to Railway Structure

This study aimed to suggest a method for assessing the liquefaction-induced damage to railway embankments, one of the major national SOC infrastructures. To achieve that purpose, the railroad design and maintenance standards in South Korea were examined, and risk assessment method was proposed. The risk assessment of liquefaction-induced damage was classified into no damage level, caution level, and critical level based on the assessment of vertical irregularity, residual settlement, and lateral displacement. To assess the liquefaction-induced damage, three simplified assessment methods and a dynamic numerical analysis method with a finite difference method were proposed. Finally, these methods were applied to the roadbed of the Honam high-speed line, and its applicability was investigated. According to the results, the related standards showed the most overestimated value of settlement among the simplified assessment methods, and the dynamic numerical analysis technique showed the most underestimated value of settlement.

Acoustic emission characteristics of Pykrete under uniaxial compression

Pykrete is a special building material suitable for cold regions. It has attracted extensive attention in recent years owing to its high strength and toughness. However, for structures constructed using Pykrete, appropriate damage detection and evaluation methods have rarely been investigated. As with most materials, the destruction of the Pykrete structure releases energy as stress waves and produces acoustic emission (AE) signals, which help understand the damage process and evaluate the degree of damage to the Pykrete. In this study, the AE technique was employed to monitor and evaluate the damage to different types of Pykretes and matrix subjected to uniaxial compression. Combined with the load-time curve, the conventional parameters of AE signals obtained from Pykretes and matrix were analyzed first. Furthermore, the failure modes of Pykretes and the matrix were investigated via the relationship between the ratio of the rise time to the waveform amplitude and the average frequency. The b-value was also calculated using the least-squares method to evaluate the failure process of Pykretes and matrix. The results show that the AE technique can qualitatively assess the damage process of Pykretes and has the potential to detect damage to actual Pykrete structures in situ.

A new endurance time analysis method for damage evaluation of high arch dams under the oblique incidence of mainshock-aftershock seismic sequences by wavelet decomposition

Pulse and oblique incidence features that may be generated by near-fault seismic sequences are neglected in current earthquake-resistant design codes for arch dams. To solve the shortcomings of endurance time analysis method which cannot consider near-fault pulse-like ground motions, this paper attempted to develop a new endurance time analysis method by wavelet decomposition to assess the differences in damage mechanisms of arch dams under the cross-stream and stream oblique incidences of near-fault seismic sequences. This study decomposed a typical near-fault earthquake into high-frequency and low-frequency ground motion through wavelet decomposition, which is used to perform several nonlinear dynamic analyses under different seismic intensities and seismic sequence incidence angles. On the basis of dynamic calculations, the local and global damage indices of the dam were presented, with a focus on the comparison of the damage distribution and damage volume ratios of arch dams under the action of single and sequence earthquakes and by analysing the damage mechanisms of arch dams under two diagonal incidence conditions at different peak accelerations. Then, the effects of different frequency components of ground motions on dam damage indices were compared, and finally, additional damage to the dam after the mainshock damage was quantified for various aftershocks. The proposed novel prediction model was used to estimate aftershock damage by considering mainshock damage. The numerical results indicate that the dam damage development is highly complex during original mainshock cross-stream and stream oblique incidences. This finding differs from dam damage that spread from the downstream face to the upstream face during the vertical incidence. The dam damage degree is smaller for the original mainshock stream oblique incidence than for the original mainshock cross-stream oblique incidence. The original aftershock induces stronger damage requirements on the damaged dam during the mainshock than during the high-frequency aftershock. Original and high-frequency seismic sequences with cross-stream and stream oblique incidences do not contribute to variations in dam damage patterns during aftershocks. Therefore, the influence of near-fault pulse impacts and the oblique incidence angle of seismic sequences need to be considered comprehensively in the seismic calculations and reinforcement studies of arch dams.

Dynamic response and damage mechanism of parallel wire cables under contact explosion

With the global threat of terrorism on the rise, the protection of important infrastructure such as cable-stayed bridges from terrorist assaults has become a major concern. In cable-stayed bridge designs, the cables are crucial load-carrying components, and their failure could result in the progressive collapse of the bridge with catastrophic results. However, there is very limited understanding of the blast effects on cables. This paper presents a study on the blast performance of parallel wire cables under contact explosions. Field blast tests were conducted on four identical parallel wire cable specimens with varying charge weights and prestress levels. Arbitrary-Lagrangian-Eulerian (ALE) algorithm is utilized to develop the numerical model in LS-DYNA. The numerical model is then validated and further used to investigate the damage mechanism of the cable under contact explosions. The results indicate that the damage process of cables under contact blasts can be divided into three stages: Compression, divergence, and stretching. The wires arranged in angular points facing the detonation are particularly vulnerable, and high-density polyethylene (HDPE) is prone to be pelted off by explosive pressure. Parametric analyses were carried out to investigate the influences of charge weight and prestressing force on the damage degree of cables. The relationship between the TNT equivalent and the number of fracture wires is derived from the parametric analysis results. Furthermore, the prestress is found to have a considerable impact on the degree of cable damage induced by contact explosions. Taking prestress into account, a damage evaluation method for blast-damaged cables is proposed.