Damage State Research Articles

Energy-based damage assessment method for masonry walls under seismic and fire loads

The evaluation of the out-of-plane (OOP) behavior for infilled walls is a critical aspect of regional seismic and fire resilience assessment. This study presents a detailed finite element (FE) model that comprehensively captures the seismic and fire behaviors of masonry walls. The FE model incorporates key factors governing the thermo-mechanical behavior of masonry walls, including temperature-dependent material properties, nonlinearities in geometry and material, block cracking and crushing, and mortar damage. Then, an energy-based damage criterion is proposed based on the principle of energy conservation, leveraging the combined mixed fracture energy and internal energy of elements. In addition, this study defines the damage levels of masonry walls under OOP loading and fire and determines corresponding damage indices using the proposed energy-based damage criterion. This criterion is further compared with a stiffness-based damage criterion. Finally, the proposed damage assessment method is employed to evaluate the damage evolution of infilled walls under seismic, fire and post-earthquake fire scenarios, and to conduct a fragility analysis. The results demonstrate a high degree of agreement between the predicted and measured damage states of masonry walls under seismic and fire loads. More severe seismic damage does not always result in diminished fire resilience. Evaluating post-earthquake fire damage requires considering the impact of displacement directions caused by earthquakes and fires.

Evaluation framework for bitumen-aggregate interfacial adhesion incorporating pull-off test and fluorescence tracing method

The interfacial adhesion between bitumen and aggregate is crucial to maintain the mechanical performance of asphalt pavement. Numerous indicators characterize the bonding ability of bitumen to aggregate; however, indicators based on limited conditions are used infrequently to effectively evaluate the interfacial adhesion between bitumen and aggregate. This study introduces a method to assess adhesion and moisture damage resistance at the bitumen-aggregate interface by combining the pull-off test with the fluorescence tracing method. The improved pull-off test considers different bitumen film thicknesses, ambient temperatures, material combinations, and moisture damage conditions, and the fluorescence tracing method and surface energy parameters are utilized to precisely detect the extent of bitumen adherence to the aggregate. The findings of this study are summarized as follows. (1) The bitumen stripping ratio characterizes the influence of ambient temperature and bitumen film thickness, and the pull-off strength/work quantifies the influence of ambient temperature and material combination. (2) The indicators derived from surface free energy theory exhibit lower sensitivity to material combinations compared with the pull-off performance indicators, with a coefficient of variation for both adhesion and stripping work of approximately 6 % compared to 14.29 %–70.13 % for the pull-off performance indicators. (3) The pull-off strength indicator dominates the pull-off performance evaluation, with the bitumen stripping ratio necessary at 0°C and pull-off work significant at 40°C to evaluate adhesive properties. In addition, the bitumen stripping ratio increment should be considered alongside pull-off strength loss ratio when estimating anti-moisture damage performance. (4) The fluorescence tracing method shows great potential in terms of enhancing the accuracy of bitumen stripping ratio detection in the pull-off test, with bitumen stripping ratio discrepancies at 0°C–40°C ranging from 0.98 % to 7.16 % for 70#-Limestone and 2.10–9.21 % for 70#-Granite. The methodology presented in this study represents a promising framework to determine the interfacial adhesive properties of asphalt mixtures with high accuracy.

Finite element analysis of rockfall impact on pipelines with different erosion resistant coatings

In this paper, the finite element analysis method is used to extensively study the response of rockfall impact on pipelines with different erosion resistant coating. Based on the numerical results, the safety of the pipeline is comprehensively evaluated. Firstly, through the establishment of detailed pipeline and rockfall models, the impact of different rockfall materials and speeds on the pipeline is simulated. The results of the finite element analysis indicate that rockfall impact can cause significant stress concentration and deformation in the pipelines and damage to the coating. With the increment of impact speed, the damage to the pipeline also increases significantly, and different rockfall materials exhibit varying damage conditions, and it is found that fibreglass reinforced epoxy is better than the polyethylene coating. By comparing the analysis results under different conditions, the safety threshold of the pipeline under various rockfall impact scenarios is obtained. This provides an important theoretical basis and reference for the protection design and safety maintenance of the pipeline. The research in this paper not only aids in deepening the understanding of the mechanism of rockfall impact on pipelines but also serves as a valuable reference for improving the safety and reliability of pipeline engineering.

Enhanced ANN-based ensemble method for bridge damage characterization using limited dataset

Bridges are vital assets of transport infrastructure, systems, and communities. Damage characterization is critical in ensuring safety and planning adaptation measures. Nondestructive methods offer an efficient means towards assessing the condition of bridges, without causing harm or disruption to transport services, and these can deploy measurable evidence of bridge deterioration, e.g., deflections due to tendon loss. This paper presents an enhanced input-doubling technique and the Artificial Neural Network (ANN)-based cascade ensemble method for bridge damage state identification and is exclusively relying on small datasets, that are common in structural assessments. A new data augmentation scheme rooted in the principles of linearizing response surfaces is introduced, which significantly boosts the efficiency of intelligent data analysis when faced with limited volumes of data. Furthermore, improvements to a two-step ANN-based ensemble method, designed for solving the stated task, are presented. By adding the improved input-doubling methods as simple predictors in the first part of the cascade ensemble and optimizing it, we significantly boost accuracy (7%, 0.5%, and 8% based on R2 in predicting tendon losses for three critical zones that were defined across the deck of a real deteriorated prestressed balanced cantilever bridge). This improvement is strong evidence of the accuracy of the proposed method for the task at hand that is proven to be more accurate than other methods available in the international literature.

Fatigue life prediction of film-cooling Hole specimens with initial damage

This study investigates a Nickel-based single crystal (SX) superalloy with femtosecond laser-drilled film-cooling holes (FCHs) under varying temperatures (room temperature, 850 °C, and 980 °C), employing a novel framework for predicting fatigue life based on initial manufacturing damage quantification. For all tested anisotropic SX superalloy specimens (including smooth and FCH specimens), the initial damage state is characterized as an equivalent initial flaw size (EIFS), and an EIFS calculation model considering stress concentration is established. Subsequently, the fatigue crack paths and microstructural characteristics of the FCH specimens at different temperatures are analyzed, elucidating crack initiation mechanisms and propagation patterns. A novel incremental plasticity J-integral driving force for fatigue crack propagation is introduced. By incorporating the closure effect of small crack propagation and employing Markov Chain Monte Carlo simulations for determining crack growth rate probabilities, a more accurate expression for the crack growth rate in relation to ΔJfat − ΔJth is derived. This expression comprehensively captures crack patterns on crystallographic planes and Type I mixed mode behavior. Finally, the total fatigue life of the FCH structures, featuring a threefold dispersion zone in both room and high-temperature environments, is predicted through experimental observations and description of crack growth rates. The predicted outcomes significantly outperform those of the conventional life prediction models reliant on crystal plasticity theory.

Nano Spirulina platensis countered cisplatin-induced repro-toxicity by reversing the expression of altered steroid hormones and downregulation of the StAR gene.

Cisplatin is a commonly utilized chemotherapy medication for treating different sarcomas and carcinomas. Its ability interferes with cancer cells' DNA repair pathways and postpones unfavorable outcomes in cancer patients. The current investigation's goal was to ascertain if nano Spirulina platensis (NSP) might shield rat testicles from cisplatin damage by assessing the expression of the StAR and SOD genes, sex hormones, 17ß-hydroxysteroid dehydrogenase(17ß-HSD), sperm profile picture, oxidative condition of testes, testicular histology, and DNA damage. Four equal and random groups of 28 adult male Wistar rats were created; the control group was given saline for 8weeks. An extraction of NSP at a concentration of 2500mg/kg body weight was administered orally for 8weeks to the NSP group. For the first 4weeks, the cisplatin group was intraperitoneally injected with 2mg/kg/body weight of cisplatin, and for the next 4weeks, they were given a dosage of 4mg/kg/body weight. The cisplatin + NSP group was given both NSP and cisplatin. The results of the experiment showed that intake of NSP and cisplatin improved sperm profile; re-established the balance of oxidizing agents and antioxidant state; enhanced testicular histology; promoted the histometric parameters of seminiferous tubules including epithelial height, their diameter, and Johnsen's score, decreasing DNA breakage in testicular tissue; increased testosterone level; decreased 17ß-HSD concentration; and upregulated both the StAR and SOD gene expression in testicles compared to rats exposed to cisplatin alone. These results demonstrate that NSP is a promising agent for improving cisplatin-induced testicular injury and infertility.

Research on the electromagnetic ultrasonic detection method of initiation crack based on multi-acoustic coefficients fusion

Abstract The traditional single acoustic coefficient cannot judge the different degrees of fatigue damage such as initiation crack and crack extension. Based on the law between the structural evolution of dislocation pile-up initiating crack and acoustic coefficients, a multi-acoustic coefficients fusion feature-fatigue damage stage detection method is proposed. By extracting the nonlinear features as well as linear features of the multi-point detection signals for a single fatigue-damaged aluminum plate, achieves the fatigue damage state. Experiments verified multi-acoustic coefficients with different features corresponding to different fatigue stages such as initiation crack and crack extension.The peak points of the acoustic nonlinear coefficients are used for the judgment of the initiation crack stage, and the peak-to-peak amplitude of the acoustic linear coefficients are used for the judgment of the crack extension stage. Comparing and analyzing the results of electromagnetic ultrasonic detection and microscopic observation of different fatigue damage stages, the proposed method provides early warning of the initiation crack and crack extension by studying the characteristics of acoustic coefficients of different fatigue damage stages. This study provides theoretical and experimental basis for the application of electromagnetic ultrasonic assessment of fatigue damage in metallic materials.

Structural response of steel-concrete composite panels to near field simultaneous blast and fragmentation loading

Steel-concrete composite sandwich panels are used in blast doors or blast walls to protect personnel and equipment in explosive environments due to their superior performance against blast effects. In the design of such panels, most design methods treat blast and fragment loading independently for far-field explosions. However, the synergistic effects of combined blast and fragments loading should be accounted for in close-in explosion scenarios. In this study, a field test program was conducted to assess the damage of the steel-concrete composite panels subjected to close-in explosion of cased charges at various scaled distance between 0.39 and 0.78 m/kg1/3. Characterization test of cased charge detonation was performed to explore the combined loading effect. The analysis includes the pressure-time history from the cased charge detonation, distribution of the fragment masses and velocities over the test panels. The structural damage and response of the composite panels against the combined loading effects was measured. The results indicated that in addition to the damage from the blast wave, the panel was remarkably damaged by the fragment impact. Despite the significant structural damage, the panels maintained its structural integrity after the tests. Additionally, quasi-static load tests were conducted on the panels to quantify their load resistant differences in pristine condition and various damaged conditions due to the explosive effects.

Investigation on the Seismic Damage and Identification of Lateral Stiffness for Ancient Timber Structures

ABSTRACTThis paper investigates the seismic damage and identification of lateral stiffness for ancient timber structures. Based on the shaking table test of a palace‐style timber structure, the lateral displacement responses, interstory equivalent lateral stiffness (IELS), and sensitivity of lateral displacement to degradation of IELS were analyzed to investigate the degradation and identification of IELS. The state and observation equations of a simplified mechanical model of the timber frame considering the friction slipping of the column base were predicted. Considering the noise disturbance in the test, the IELS of the model was identified by the partial least squares–singular value decomposition (PLS‐SVD) and extended Kalman filter (EKF) method. Results shown that the ratio of the IELS of the column frame layer to Ru‐Fu layer decreased as the seismic damage increased, and the peak lateral displacement was more sensitive to the damage of the column frame layer than the Ru‐Fu layer. Under nondamage conditions, the identification error of the IELS was about 10%, while the error ranged from 15% to 20% under damage conditions. Through the identification of the equivalent lateral stiffness of the Xi'an bell tower, it was validated that the hybrid method is effective in monitoring the IELS of ancient timber structures.

Application of integrated geodetic and UAV technologies for monitoring environmental changes due to the mining activities in Solotvyno salt mine, Ukraine

This paper covers the spatio-temporal evolution of land surface deformation in the Tisza River basin within the Transcarpathian region, analyzing geodetic observations obtained over the last decade. In the town of Solotvyno, in the western part of Ukraine, near the Romanian border, there is an abandoned salt deposit where salt was extracted in several mining operations. In 2010, the mine was closed, and mine chambers 7 and 8 were flooded with water, causing the collapse of this region. Since then, the extent of the damage has been increasing, with sinkholes steadily growing larger and larger, threatening not only the entire surface area around the quarry but especially the groundwater that connects the deposit to the Tisza River. Several research institutions have been involved in monitoring the shifts over time. We have monitored the karst by identifying the most dangerous areas of the earth's surface subject to vertical shifts - trench sinkholes by UAV survey and terrestrial measurements using precise levelling in 4 stages. The situation on the site is an emergency with a major ecological impact of salt contamination in the whole Upper Tisza Basin region and requires not only continuous geodetic, geological, and chemical monitoring but especially an urgent solution to reverse the state of damage to the region.

Whale Optimization Algorithm for structural damage detection, localization, and quantification

This paper introduces an approach for vibration-based damage detection based on matrix updating aided by the Whale Optimization Algorithm (WOA). The methodology uses the Data-driven Stochastic Subspace Identification (SSI-DATA) technique to determine the modal parameters, which are compared with those obtained from both healthy and damaged conditions of the structure. The methodology’s efficacy is assessed through three distinct steps: numerical simulations, experimental data, and real-world data from a bridge. Initially, numerical analyses are conducted on a cantilever beam, a 10-bar truss, and a Warren truss subjected to environmental vibrations with varying damage cases and noise levels. Subsequently, experimental validations are performed on a test system and in the Z24 Bridge. Results from the computational simulations demonstrate the method’s promise to identify, locate, and quantify single and multiple damage cases, even amidst signal noise, variations in the first vibration mode as minimal as 0.015%, and complex structures with 54 elements. Moreover, the matrix updating method utilizing WOA showcased superior accuracy compared to existing techniques in the literature. In addition, the Z24 Bridge example validated the capability of the presented damage detection method to localize structural damage solely based on natural frequencies.

Damage index correlation in massive granite-porous backfills under hydromechanical triaxial cyclic loading using acoustic emissions and X-ray computed tomography

The characterization accuracy of damage indices in massive and porous composite biomaterials under complex osmotic conditions has long been a challenge in engineering materials science. Establishing correlations between damage indices calculated using different methodologies is crucial to validate and improve defects characterizations. In this study, we investigated the damage index correlation of cylindrical massive granite-porous backfill structural composites under both dry and seepage conditions. A series of triaxial cyclic loading and unloading tests were conducted on specimens under hydromechanical conditions with varying osmotic pressures (0, 1, 3, 5, 7, and 9 MPa) and a confining pressure of 9 MPa involving acoustic emission monitoring and phase-based 3D nondestructive CT scanning. The results revealed the AE energy was lower under osmotic conditions compared to dry conditions. The AE Damage Index (DAE), defined by separating tensile and shear microcracking signals, significantly increased from 0.32 to 0.55 with rising osmotic pressure. 3D mesoscopic fracture visualization provided detailed insights into the fractures in granite and backfill interfaces. The number of small-angle cracks increased with osmotic pressure, and the crack inclination distribution range expanded from 63°- 85° to 49°–80°. The average crack angle showed a significant monotonic decrease with increasing osmotic pressure. An Energy Dissipation Damage Index (DED) was defined, and its correlation with the DAE under dry conditions was modeled using a reciprocal function DED=a/(DAE+bσ3)+c. This novel approach offers insights into the transition points between tensile and shear-dominated failure stages. Furthermore, an exponential function DV=aDAEb(b<0) was used to model the correlation between AE Damage Index and Visual Damage Index (DV) under osmotic conditions. The damage indices derived from different methods can be mathematically correlated, providing a comprehensive evaluation of material damage states. The study found the flow transition between different natural-human medias results in different damage mechanisms, which are all obey the correlation law. These damage mechanisms offered constructive recommendations for engineering applications based on varying ratios of osmotic pressure to confining pressure.

Numerical Analysis and Safety Assessment of the Former Site of Shanghai South Downtown Library Reinforced by U-Steel During Integral Translation

ABSTRACT The utilization of overall translation techniques in buildings offers numerous advantages, including cost-effectiveness, shortened construction timelines, and environmental sustainability. These techniques are increasingly being employed for the conservation and renovation of existing historic structures. Taking the former site project of the South Downtown Library in Shanghai, which requires the overall translation due to the requirements of urban renewal, as an example, a systematic detection and identification of the damage and safety states of the overall structure were conducted. The damaged condition and overall structural safety were evaluated, and the corresponding reinforcement and repair suggestions were proposed. The former site of the library, a brick-timber mixed structure, was reinforced using U-steel through internal support and external pulling. The structure was also lifted and translated using the overall translation technique. The displacement responses of the key parts of the structure were monitored using the displacement sensors during the translation. The detailed finite element model of the former site of the Shanghai south downtown library, strengthened by U-steel, was established using the ABAQUS. The displacement responses of the structure’s key components during the jacking and translation were analyzed, and compared with the actual monitoring results. Good agreements were observed between the model predictions and test results. Utilizing the validated finite element model, parametric analyses were carried out. The effects of the rate of jacking and translation as well as the ground flatness on the displacement responses of a structure were analyzed, the mechanical and safety states of the structure reinforced with U-steel were further evaluated. This study can provide a reference for the overall translation technique and safety assessment of similar historic buildings in the urban renewal processes.

Quantifying Seismic Damage in RC Walls with Image Analysis

ABSTRACT This study presents an image-assisted method for seismic damage evaluation of RC walls, integrating image processing, feature ranking, and machine learning. The method utilizes features from surface crack images, such as crack patterns and ratios, combined with design parameters, to predict damage levels and states. Seismic damage evaluation tools based on damage state, strength degradation, and drift ratio are introduced as indicators for quantifying structural damage. The approach is tested using 450 crack images, and feature selection was applied to identify the most important predictors. The results demonstrate high accuracy with an R-squared of 0.87 and an RMSE of 0.28.

Post impact flexural behavior investigation of hybrid foam-core sandwich composites at extreme Arctic temperature

This study explores the post-impact bending behavior and failure mechanisms in hybrid sandwich composites made of Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP). Flexural tests conducted at both ambient room temperature and low temperature Arctic conditions reveal a significant enhancement in flexural performance when GFRP layer is incorporated on the outer side of the hybrid composite. The investigation utilizes images from testing to elucidate damage modes, including fiber and matrix cracking in the composite facesheet, as well as core shearing and debonding in the Polyvinyl Chloride (PVC) foam core. Residual flexural properties are notably influenced by stacking sequence, facesheet compressive properties, pre-existing impact damage and temperature conditions. Analytical predictions, validated experimentally, highlight the effect of stacking sequence, low temperature, and impact energy on flexural collapse modes, with competing failure modes such as indentation and core shear. Collapse maps indicate that room temperature specimens predominantly collapse through indentation, while diverse collapse mechanisms emerge due to facesheet thickness, rigidity, and degraded tensile strength. The study aims to provide fundamental insights for future composite designs tailored for Arctic applications.

Fast concrete crack depth detection using low frequency ultrasound array SH waves data

Fast detection of the depths of surface-open cracks plays an important role in evaluating the damage conditions of concrete elements. The presence of surface-open cracks and other anomalies inside concrete complicates the ultrasonic wave field and thus severely undermines the precision of traditional nondestructive testing methods. This study introduces independently developed low-frequency ultrasonic array detection equipment. The detector adopts a doubled-ray coverage strategy to enhance the imaging stability under noisy conditions. Moreover, we propose an imaging method called the crack focusing-synthetic aperture focusing technique (CF-SAFT), through which both reflected and transmitted surface waves are removed so that only diffracted SH waves converge to their origins. An extra instantaneous phase analysis is supplemented to highlight the diffraction points. We test the effectiveness of our method through a multitude of numerical examples and a model experiment. Successful depth identification was obtained regardless of different geometries of the cracks or interference from the steel reinforcements. The superiority of our method is further verified through noisy ultrasonic data and complex scenarios.

Passive defect localization on a vibrating plate using Matched-Field Processing

Passive defect localization on a vibrating plate using Matched-Field Processing (MFP). The aim of this study is to investigate the use of MFP for passive localization of a local change in parameter of a vibrating shell in the modal regime. Matched-Field Processing is a beamforming method that uses the correlation between the recorded data and a controllable digital model of wave propagation (replica) to locate a source. Vibration measurements were conducted on an aluminum plate using a laser vibrometer. The plate was tested both with and without damage (added mass) while being excited by a shaker. Replicas were created by performing modal analysis on measurements taken from the undamaged structure. Matched-Field Processing is applied directly to the measured data to locate the active source (shaker) and to the residues (field difference between undamaged and damaged states) to locate a local variation of the parameter (defect). The method's feasibility is also being explored for passive measurements in modal analysis and residue computation.

Surface matching design of carbon fiber composite honeycomb

Applying carbon fiber composite honeycomb in curved sandwich shells faces challenges due to the saddle-shaped bending surface in hexagon configurations and potential damage during the shape-forming process. This study analyzes the bending deformation of honeycombs by developing large deformation theoretical model for their bending surfaces. The study introduces two novel honeycomb configurations—Boomerang-shaped with a positive Poisson's ratio and Jellyfish-shaped with a negative Poisson's ratio—achieved through curved-wall design and fabrication using a modified carbon fiber composite tape winding molding process. Experimental tests, including bending deformation and shape-forming tests, measure the three-dimensional bending surfaces and mechanical responses of carbon fiber composite honeycombs. Additionally, a developed finite element model analyzes the damage states of various carbon fiber composite honeycombs during shape-forming processes. The results reveal the bending deformation of carbon fiber composite honeycombs and present damage state cloud maps to facilitate the optimal matching of objective sandwich shells with minimal scathe.

Nonlinear ultrasonic test applied to discern factors controlling cracking of cement mortar affected by reinforcement corrosion

Intermodulation ultrasonic testing technique was used to detect corrosion- induced cracking in prismatic mortar samples. Three sets of five specimens were prepared and subjected to accelerated corrosion conditions. The different times of exposure allowed to attain unlike damage conditions in every sample of each set. The onset of damage was monitored through the evolution of the accumulated Intensity Modulation Ratio (R) and crack width measurements. The accumulated values of the Intensity Modulation Ratio were used to study the effect of different testing factors (cover depth, corrosion rate or amplitude of the input pump signal) and increased monotonically clearly discriminating the different damage levels. These observations point to the possibility of stablishing damage thresholds to detect cracking using nonlinear ultrasonic (NLU) techniques.

Structural and non-structural fragility curves for low-rise mainshock-damaged buildings subjected to aftershocks

The seismic response of mainshock-damaged buildings under aftershocks is an important topic in terms of the lateral response of damaged structures. The majority of current seismic design standards just consider a single earthquake (mainshock/design earthquake) and they don’t take into account the influence of aftershocks on the seismic design process. The aftershocks could have significant effects on the seismic response of mainshock-damaged structures. This situation was reported in some of the previous earthquake events in which the aftershocks caused additional damage to the structures. In this study, the fragility curves for structural and non-structural Drift-Sensitive Components (DSCs) and Acceleration-Sensitive Components (ASCs) of two low-rise mainshock-damaged moment resisting steel and reinforcement concrete buildings under the effect of aftershocks with different intensities were presented. The intensity of the mainshocks was adjusted until the intact buildings experienced three levels of damage states including slight, moderate and extensive damage states. After that, the fragility curve of the structural and non-structural components of the mainshock-damaged buildings under the effect of aftershocks was evaluated by the Incremental Dynamic Analysis (IDA). The results show that the effect of aftershocks on the probability of damage to structural and non-structural components of mainshock-damaged structures is related to the level of the initial damage. For slightly and moderately mainshock-damaged buildings, the probability of exceedance of the damage under aftershocks is relatively similar to the intact buildings, however, the aftershocks significantly increase the probability of damage to the extensively mainshock-damaged buildings. Although extensive initial damage causes a significant increase in the probability of damage to non-structural DSCs, the damage probability of non-structural ASCs remains relatively as similar to intact buildings. Regarding the HAZUS manual, the results show that the probability of damage exceedance of the structural components is higher than non-structural ASCs, however, the opposite observation was reported from the previous earthquakes. Therefore, in this study, four levels of damage threshold for non-structural ASCs are proposed.