Damage Patterns Research Articles

Interdisciplinary Management of Traumatic Injuries to the Kidneys and Urinary Tract Caused by Blunt Abdominopelvic Trauma.

Purpose: Blunt abdominopelvic trauma frequently results in injuries to the urinary organs, especially in polytrauma. The urotrauma is rarely an acute life-threatening event; however, it may lead to severe complications. Methods: This review addresses the under-representation of urological trauma management in interdisciplinary medical training and its impact on patient outcomes. It compiles evidence-based recommendations and guidelines from multiple specialties, focusing on common challenges in managing these injuries. The resource is tailored for primary care physicians in radiology, trauma surgery, internal medicine, urology, and nephrology. Results: Urinary tract injuries can occur even if the patient's condition initially appears normal. An exclusion diagnosis is obligatory by contrast medium tomography of the entire urinary tract and, if suspected, an additional uroendoscopic examination. Interventional therapy by catheterisation of the urinary tract is often required. Urosurgical treatment is not commonly needed, but when there is a demand, it must be administered via an interdisciplinary approach with visceral and trauma surgery. Over 90% of life-threatening kidney injuries (usually up to grade 4-5 AAST) are presently treated by interventional radiologists. Acute kidney injury (AKI) as a complication in trauma patients may complicate clinical management and often worsens the outcome. The incidence of trauma-associated AKI in patients admitted to an intensive care unit is high. Conclusions: Patients suffering from blunt abdominopelvic trauma should ideally be referred to certified trauma centres with subspecialised or fully specialised care provided by visceral/vascular surgery, trauma surgery, interventional radiology, urology, and nephrology. This recommendation is based on the complex nature of most damage patterns.

A unified modeling approach for concrete masonry shear walls: Conception, validation and insights

Distinct modeling strategies have been developed to simulate concrete masonry shear walls; however, each is validated with a limited number of specimens tested under identical laboratory conditions and only covers specific detailing scenarios. This research seeks a unified finite element-based modeling approach integrating macro-modeling concepts for grouted masonry (GM) regions and simplified micro-modeling for ungrouted masonry (UGM) regions. The objective is to facilitate accurate simulation of the in-plane behavior of diverse typologies of concrete masonry shear walls: unreinforced masonry (URM), fully grouted reinforced masonry (FGRM), and partially grouted reinforced masonry (PGRM). A smeared crack approach is used to capture the crushing and cracking of grouted masonry (GM) and ungrouted masonry (UGM), and interface elements are incorporated into UGM regions to model the mortar joints, resulting in a combined smeared-discrete model. The validation process comprises two levels. The first-level evaluation focuses on URM and FGRM walls, emphasizing the analysis and comparison of lateral force–displacement curves. Second-level validation is done through simulation of PGRM walls by evaluating lateral force–displacement curves, damage patterns, and reinforcement strains. The implemented modeling approach generally simulates the response of the different experimental masonry shear walls evaluated with good accuracy. A sensitivity analysis was also performed to reveal the influence of some parameters on the numerical results, providing additional perceptions into the reliability of the modeling approach. Relevant insights into the modeling approach were obtained, allowing complex phenomena in the tested walls to be simulated, thus contributing to advances in the simulation of in-plane loaded concrete masonry walls.

Spatial patterns of damage and tree mortality in a selectively logged Atlantic Forest

Selective logging, a common disturbance in mixed-species and uneven-aged forests, can cause substantial collateral stand damage and tree mortality. Here we explore damage patterns and some mechanisms that increase post-harvest tree mortality in a selectively logged subtropical Atlantic Forest in Argentina. We investigate the spatial relations of felled and damaged trees through spatial point pattern analysis and evaluate the relationships between mortality and different endogenous (size - diameter at breast height: DBH; and wood density: WD) and exogenous (damage and neighboring basal area: NBA) factors. The permanent plots were logged in 1999, and the fates of all pre-logging live trees ≥10 cm DBH were evaluated 20 years later. Of the monitored 3973 trees, 381 with damaged concentrated within 10.5 m of felled tree stumps. Over the next twenty years mean mortality was higher and more variable for damaged than undamaged trees (47 % ± 10 % SE and 39 % ± 2 % SE, respectively), and the presence of damage interacted with the other analyzed factors. For undamaged trees, the probability of mortality declined with DBH and NBA but not with WD. For damaged trees, instead, the probability of mortality was related to an interaction between DBH, WD, and NBA. For damaged trees <30 cm DBH, mortality increased with WD and NBA, whereas for damaged trees ≥30 cm DBH, mortality peaked at both extremes of the WD range. For these large trees with low WD, the probability of mortality decreased with NBA, whereas for trees with high WD, the opposite was observed. Our findings suggest that selective logging affects the dynamics of forests by spatially concentrating damage and may alter subsequent tree deaths. This could have, long-term effects on forest structure. Increases in logging intensity would increase overall damage and spatially isolate trees (i.e., lower NBA), rendering them more vulnerable to wind damage and other external factors. Increased tree mortality will reduce forest carbon stocks and thereby jeopardize global efforts to mitigate climate change.

Cyclic seismic pushover testing of a multi-story underground station

The experimental approach is crucial for investigating the seismic performance and damage process of underground structures. Considering the shortcomings of the 1-g, centrifuge shaking table and monotonic displacement pushover tests, a large-scale cyclic displacement pushover test method is proposed based on the soil-underground structure dynamic interaction and seismic performance quantification system. Taking a two-story three-span subway station structure as the prototype, the cyclic displacement pushover test device was designed for a 1/7-scale multi-story subway station based on the seismic response characteristics of underground structures. The corresponding numerical simulations and experiments were conducted. Typical numerical results (including the seismic damage process, capacity curves of the structural columns, and strain response) and test results (the macroscopic phenomenon of structural damage development, strain response, and deformation response) are interpreted. The results show that the proposed cyclic displacement pushover test is better than the monotonic displacement pushover test, the damage process of the tested station structure conforms to the description of the inter-story drift ratio (IDR) quantification system of seismic performance. Meanwhile, the column has greater strain amplitudes than other components, and the column strain curves reach their peaks before other components. Furthermore, the tested station structure has a similar damage pattern to the Daikai subway station. The reliability and feasibility of the proposed cyclic displacement pushover test method are verified.

Compressive and flexural properties and damage modes of aluminum foam/epoxy resin interpenetrating phase composites reinforced by silica powder

AbstractInterpenetrating phase composites (IPCs) can combine the advantages of each component and have a good application prospect. IPCs were prepared by combining open‐cell aluminum foam (AF) and epoxy resin (EP) in three‐dimensional space in this study. Different contents of silica powder (SP, 80, 100, 120, and 140 wt%) were added to EP to improve the compressive and three‐point bending properties of IPCs. In the bending test, acoustic emission (AE) was applied to track the bending deformation of the samples, and k‐means clustering algorithm was applied to identify the damage modes. The compressive and bending properties of IPCs increased first and then decreased with the increase of SP content, and reached the maximum when the SP content was 100 wt%, with a compressive yield strength of 74.6 MPa and a bending peak load of 1.96 kN. The performance degradation was mainly attributed to the AF/EP debonding due to SP distribution at the interface. The X‐type shear band and EP/AF debonding appeared in compression failures of AF and IPCs, respectively. The AE clustering results showed that under bending load, plastic deformation of matrix (60–200 kHz) and fracture failure (230–340 kHz) modes appeared in AF, while EP/AF debonding (60–120 kHz), EP failure (120–230 kHz) and plastic deformation of foam matrix (230–250 kHz) modes appeared in IPCs.Highlights Silica powder was added to improve compressive and bending properties of IPCs. Acoustic emission was used to monitor bending of foam and IPCs firstly. k‐means clustering was used to identify and classify bending damage patterns.

Shaking table test of a full-scale lightweight bolt-connected concrete sandwich wall panel structure: Overview and seismic analyses

This study proposed a novel lightweight bolt-connected concrete sandwich wall panel structure with the advantages of thermal insulation, construction efficiency, demountability and remountability. The seismic design of the structure was employed a non-equivalent cast-in-place method, resulting in appropriate configurations of horizontal and vertical bolted joints. Subsequently, a shaking table test was carried out to investigate the damage pattern, dynamic characteristics and dynamic responses of a full-scale structure. The test results demonstrated that the overall damage was moderate, which exerted a few impacts on the structural capacity or integrity. The global responses, including small displacement response, minor torsion response, and high energy dissipation capacity were found, as well as local responses, such as small strains in the steel plates and a slight loss of bolt prestress. The maximum inter-story drift ratio was below the elastoplastic inter-story drift ratio limit θu = 1/120 defined in Chinese code GB 50011. In general, the structure presented high lateral stiffness and sufficient capacity against high-intensity ground motions. A numerical model was developed, wherein precast components were established by multi-layer shell elements and bolted joints were simulated by 3-DoF nonlinear springs. Linear modal and nonlinear time history analyses were performed and compared with the experimental results. The simulation results showed good agreement with the experimental ones, confirming the ability of the model to capture global responses.

CRACKING PATTERN ANALYSIS OF THE TURNING BAND METHOD (TBM) APPLICATION ON A SINGLE-REINFORCEMENT BAR CONCRETE BEAM MODELLING USING THE MAZARS DAMAGE

The development of crack patterns in reinforced concrete structures is a randomly stochastic process influenced by the heterogeneous nature of concrete materials, which impacts the sensitivity to damage and variability in mechanical properties. The numerical simulation of damage pattern appearance on the reinforced concrete for special building structures needs a realistic result, especially in terms of crack distribution. The Turning Band Method (TBM) serves as a tool for assessing the variability of concrete heterogeneity, functioning as an operator to generate a random variable for each specific field. In this study, the investigation of crack patterns in reinforced concrete structures involves using a simple concrete beam sample, measuring 10x10x50 cm3, with a single longitudinal reinforcement cast in the centre. This beam is subjected to an axial tensile loading, while the Mazar Damage Model is employed as the concrete behaviour law. Through the implementation of The Turning Band Method (TBM) and the variation of the random field parameters, distinct crack patterns are observed, not only the number but also the locations of cracks. The use of a smaller correlation length showed 2 cracks while the larger size had around 1 to 3 cracks, with the first crack localizations of each sample generally occurring in the middle surface, in which a noticeable contrast to non-TBM modelling just displays 1 crack. Furthermore, the resulting probability of cracks for ten random draws demonstrates similarity to experimental tests and numerical simulation of the previous study, both at global and local levels.

Analysis of seismic damage and seismic capacity of the structure of the ultrahigh pagoda

AbstractThe Chongwen Pagoda is the tallest masonry pagoda in China, with numerous openings inside the pagoda body. It is prone to damage during earthquakes, and the patterns of damage are complex. In order to scientifically analyze the dynamic performance, earthquake damage patterns, and mechanisms of the pagoda structure, on‐site dynamic testing was conducted to obtain the dynamic characteristics of the structure. A numerical model was established using Abaqus finite element software to calculate the dynamic characteristics of the structure. The results were compared with the testing results and showed a close agreement. El‐Centro earthquake wave, Taft earthquake wave, and Lanzhou artificial earthquake wave were selected as earthquake inputs based on site conditions, simulating frequent earthquakes, fortification earthquakes, and rare earthquakes with a magnitude of 9. The dynamic response of the pagoda structure was calculated, and the relationship between acceleration amplification factor, interstorey displacement, and interstorey displacement angle with floor height was analyzed. The seismic damage to the structure and the distribution of primary tensile stresses were studied, revealing the seismic damage mechanisms and the distribution characteristics of vulnerable areas in the Chongwen Pagoda. The research results provide references for the seismic assessment of this ancient pagoda.

A Short-Term Study of 18 Cases of Distal Femur Fractures Managed By Locking Compression Plate [Lcp] Using A Less Invasive Skeletal Stabilisation System [LISS

Distal femur fractures have traditionally been the most challenging to treat. Restoring full motion and function to the knee may be challenging due to these fractures' proximity to the knee joint. Regardless of the treatment method, comminution, damage of soft tissue, fracture extension into the knee joint, and related injury to the quadriceps mechanism frequently concludes in suboptimal outcomes. The early surgical fixation notion, increased implant availability, early postoperative knee joint immobilization, and a better understanding of damage patterns have all significantly improved the patient's functional result. Our study focuses on distal femur fractures managed by LCP [locking compression plate] using a less invasive skeletal stabilization system [LISS]. This is a retrospective research of 18 cases of distal femur fractures in adults who had LCP treatment with the LISS. The operation at Saveetha Medical College and Hospital in Chennai runs from January 2021 to January 2022. All types of intercondylar and supracondylar fractures are included. Children's fractures and pathological fractures were not included. Age distribution, side of injury, sex distribution, anatomy of injury, mechanism of injury, damage grading, subtype of fracture, concomitant injuries, and open fractures were the parameters used to assess the cases. AP and lateral views of the X-ray were taken. A thorough preoperative workup was completed. Every case was scheduled for surgery as soon as feasible. External fixators were used in the initial treatment of complicated cases. Patients underwent locking compression plate (LCP) fixation with the LISS. Radiological examination immediately following surgery, four weeks, six weeks, eight weeks, twelve weeks, four months, and every six months for a maximum of one year.The age range of the patients was 21 to 70 years, with a mean age of 30 years. A maximum incidence of fractures was noted in individuals aged 40 to 60. Males accounted for the majority of the 18 cases, with a female-to-male ratio of 3:5. Our series was predominantly right-sided. The most frequent cause of injury has been traffic accidents. Throughout the research period, no patients were lost to follow-up. Of the eighteen cases, the majority involved distal femur fractures, with intercondylar extension accounting for a higher number of cases, and isolated supracondylar fractures following. A head injury was present in one case, and acetabular fracture in another, a Boxer’s fracturein a third case, and 2 open fractures (1 compound grade III A, the other compound grade II). The fractures took an average of 13.3 weeks to heal. It required an average of 15.3 weeks longer in cases of compound fractures. Less than six degrees of malalignment (varus, valgus) were present. Every patient exhibited optimal articular alignment.Excellent outcomes were obtained with the LISS, which combines appropriate physiotherapy with an LCP (angle stable build). In principle, an LCP implant is the best option for fractured and osteoporotic bones. In summary, the use of LCPs in the LISS appears to yield superior outcomes when managing distal femur fractures.

Promoting Gas Extraction Technology with Screen Pipe for Long Borehole Protection in Soft Seam

The inherent properties of soft coal seams and their mechanical environment make long boreholes susceptible to issues like collapse, deformation, and blockages. These problems shorten the service life of the boreholes and hinder extraction efficiency. This paper tackles these challenges by analyzing the deformation and damage patterns of long boreholes in soft coal seams. It examines the stress distribution and deformation characteristics around both protected and unprotected boreholes at different burial depths. Additionally, it recommends using screen pipe protection technology to improve gas extraction and mining operations, as demonstrated in Changping Coal Mine. The results show that screen pipe protection substantially improves the stress distribution and deformation stability of coal seam boreholes. The flow attenuation coefficients of two boreholes equipped with protection technology decreased by 48% and 61%. After 50 days of extraction from boreholes with a protection rate exceeding 90%, gas concentration remained above 50%, which is 2.59 times higher than that of unprotected boreholes. This technology effectively addresses the frequent accidents, poor extraction performance, and inefficiency of long boreholes in soft coal seams, ensuring the mine’s safe and efficient production.

Close-in explosion performances and damage evaluation of bamboo fiber reinforced laminates

Three types of laminated bamboo plates (LBPs), namely flat-pressed one-way plate (PR), flat-pressed orthogonal plate (PC), and side-pressed one-way plate (PT), were designed and manufactured to investigate their mechanical responses under quasi-static and blast loadings. The experimental results show that the LBPs have excellent blast resistance. In-field explosion experiments clearly reveal the damage patterns of the LBPs with scaled distance changing from 2.052 m/kg1/3 to 0.054 m/kg1/3. Plates PR and PT have five damage patterns, which are slightly scorched, matrix cracking, fiber breakage, spalling and outbreak-crash, respectively. Plates PC eliminate the matrix cracking damage pattern through balancing the anisotropy by orthogonal structure. After explosion, the LBPs still maintain good elasticity, structural integrity and high residual bearing capacity. The residual bearing capacity of plates PR-1, PT-1 and PC-1 repetitively suffered seven explosions is decreased to 58.8 %, 42.6 % and 68.7 % of the average bearing capacity of the reference plates, respectively. It is concluded that orthogonal and side-pressed structures are conducive to enhance the load carrying capacity of the LBP.

Experimental and Simulation Study on Failure of Thermoplastic Carbon Fiber Composite Laminates under Low-Velocity Impact.

Numerous studies have demonstrated that under low-velocity, low-energy impact conditions, although the surface damage to fiber-reinforced composite laminates may be minimal, significant internal damage can occur. Consequently, a progressive damage finite element model was specifically developed for thermoplastic carbon fiber-reinforced composite laminates subjected to low-speed impact loads, with the objective of analyzing the damage behavior of laminates under impacts of varying energy levels. The model utilizes a three-dimensional Hashin criterion for predicting intralayer damage initiation, with cohesive elements based on bilinear traction-separation law for predicting interlaminar delamination initiation, and incorporates a damage constitutive model based on equivalent displacement to characterize fiber damage evolution, along with the B-K criterion for interlaminar damage evolution. The impact response of laminates at energy levels of 5 J, 10 J, 15 J, 20 J, and 25 J was analyzed through numerical simulation, drop-hammer experiments, and XCT non-destructive testing. The results indicated that the simulation outcomes closely correspond with the experimental findings, with both the predicted peak error and absorbed energy error maintained within a 5% margin, and the trends of the mechanical response curves aligning closely with the experimental data. The damage patterns predicted by the numerical simulations were consistent with the results obtained from XCT scans. The study additionally revealed that the impact damage of the laminates primarily stems from interlaminar delamination and intralayer tensile failure. Initial damage typically presents as internal delamination; hence, enhancing interlaminar bonding performance can significantly augment the overall load-bearing capacity of the laminate.

Study on energy consumption and failure mechanism of water-saturated coal sample during impact cracking

To uncover the mechanism of energy dissipation in coal samples when subjected to both water and dynamic load, the damage patterns and energy absorption properties of coal samples in their natural and saturated states were investigated and analyzed through Hopkinson impact experiments. The results of the study show that the mass and wave velocity of the natural coal samples show an increasing trend when they are saturated with water. And the mass and wave velocity increase by 6.35 % and 21.42 % respectively. The coal sample's level of fragmentation and dynamic strength exhibited a positive correlation with the velocity (1 m/s-5.69 m/s) of impact. When subjected to dynamic loads, both natural and water-saturated coal samples primarily undergo splitting, fracturing, and crushing. Compared with natural coal samples, saturated water coal samples show greater degree of crushing and lower mechanical strength. The dynamic strength of saturated coal sample at 5.25 m/s (15.66 MPa) decreased by 33.86 % compared with that at 5.69 m/s (23.68 MPa). The mean size of particles in coal samples, both in their natural state and when saturated with water, had an linear reduction relationship with impact speed. Conversely, the fractal dimension, which represents dissipation, had a direct relationship with impact speed. The fractal dimensions of dry and saturated coal samples are distributed in the ranges of 1.56–2.08 and 1.65–2.1, respectively. And the dissipative energy of natural coal samples between 1.09 m/s and 5.67 m/s is about 0.039 J/cm3-0.175 J/cm3, and that of saturated coal samples between 1 m/s and 5.25 m/s is about 0.034 J/cm3-0.088 J/cm3. The surface energy of coal samples was analysed and calculated, and an energy consumption prediction model was proposed to predict the energy consumption of coal samples after dynamic crushing.

Investigating the simulation test and acoustic emission characteristics of structural-control type rockbursts in deep underground environments

Deep underground projects are in a complex in-situ stress environment, and rock burst disasters induced by the hard and brittle failure of the rock mass are prone to occur around the tunnel openings. In this study, we aim to investigate the impacts of geological weak surfaces in rock masses on rockbursts and the spatiotemporal evolution of microcracks during the development of rockbursts. To achieve this objective, two sets of cubic specimens containing a circular through-hole were designed. One set of specimens had prefabricated unfilled cracks around the openings. Subsequently, the rockburst development process within the deep tunnel was replicated by subjecting both groups of specimens to identical gradient loading using a true triaxial test system. During the test, a micro camera was used to record the failure of the borehole wall in real-time, and an acoustic emission monitoring system was utilized to capture the stress waves released during structural damage. Finally, a multi-level synergistic analysis of the rockburst damage mechanism was carried out based on the macro-imaging data and micro-acoustic emission data. The results show that failure in high-stress environments within tunnels mainly includes microcrack initiation, particle ejection, crack propagation, local cracking, slabbing spalling, damage penetration, and rockburst damage. The time–frequency domain information of acoustic emission signals is highly perceptive and representative of the structural damage state of the specimens. The mutation characteristics observed in time-domain parameters, such as acoustic emission amplitude, event rate, ringing, and cumulative energy, correspond to drastic alterations in the internal structure of the rock. The distribution characteristics of frequency-domain parameters, such as acoustic emission peak frequency, dominant frequency energy, and frequency centroid, reflect different crack scales and damage modes. The diffusion of frequency centroid indicates that the damage and failure patterns within the rock are evolving towards a more complex direction. The energy magnitude of acoustic emissions represents the damage intensity during the development of rockburst. The root causes of induced structural-control type rockbursts in deep hard brittle rock masses are the combined effects of localized high-stress concentrations and large-scale discontinuous geological structures, such as natural joints, fissures, and structural planes. The naturally occurring large-scale through-type geological weak surfaces within the rock mass reduce the strength of the surrounding rock, alter the location of stress concentration, and change the initial damage characteristics. Moreover, they promote the evolution of rockbursts, thereby increasing their destructive intensity.

Seismic Performance Analysis of the Internal Joint in the New Demountable Fabricated Concrete Frame with Prestressed Mortise–Tenon Connections

This paper proposed a novel demountable fabricated joint in frame, which is connected by the prestressed and mortise–tenon connection. The prefabricated components of the demountable structures are designed to be reused, and the joint presented in this paper will promote the sustainable application of prefabricated components in future. The damage process and damage pattern of the internal joints under the horizontal load were analyzed using the refined numerical analysis model based on ABAQUS 6.14. Parametric analyses were conducted simultaneously for five parameters: axial compression ratio, the area and effective initial stress of unbonded prestressed strands (UPSs), the local reinforcement ratio in the core zone of the demountable joint, and the friction coefficient between the interface of concrete. The results showed that the demountable joint exhibits excellent energy dissipation potential under horizontal loads, but the damage was concentrated in the core zone. The deformation of the joint mainly consisted of the self-deformation of the prefabricated components, including bending, bearing and shear, as well as the relative slip deformation between the prefabricated components. The axial compression ratio has a more significant effect on the hysteresis performance compared to the areas of the UPSs and the reinforcement ratio. The initial effective stress of the UPS and the friction coefficient have relatively minor influence on the hysteretic performance of the joint. Finally, this paper recommends the design parameter values (axial compression ratio should not exceed 0.4, area of unbonded prestressed reinforcement should be not lower than Asn=0.02 and not higher than Asn=0.1, the initial stress of the UPS takes the value of 0.75fpu) and outlines optimization measures.

A case study comparing seismic retrofitting techniques for a historically significant masonry building’s minaret

Historical masonry structures are extremely susceptible to earthquakes due to their characteristic features. Seismic performance and corresponding damage patterns vary between these buildings. Even though the main structure was undamaged, many minarets suffered damage or collapsed due to the transmission of large forces from the main mass to the minaret and the abrupt changes in cross-section due to the geometry of the minaret. This study uses an ancient masonry mosque as a case study, whose minaret and main building are constructed as a single structure. The mosque’s minaret under seismic excitation is the focus of this study. The adopted model is called Alaeddin Bey Mosque in Muş, Türkiye. The seismic performance assessment of the minaret, considering various retrofitting options, is mainly based on four critical parameters: base shear, acceleration, displacement, and maximum tensile forces in all three dimensions. The analyzed retrofitting methods include base isolation located in the basement of the mosque, viscous dampers placed only in the upper part of the minaret, Carbon Fiber-Reinforced Polymer fabric fitted to only the minaret, and steel plates applied to only the minaret. Representative structural models of the mosque have been modelled with SAP2000 software. The main novelty of this study is the use of viscous dampers in the minaret. It is the first time a design methodology has been introduced for viscous damper applications in minarets. This methodology aims to prevent local damage to the minaret due to the forces generated by the dampers, while also considering the constraints of limited internal space within the minaret. The finding of this study shows that viscous damper application yields significantly better results compared to the application of Carbon Fiber-Reinforced Polymer fabric and steel plates. However, although base isolation reduces the tensile stress values throughout the entire mosque to levels well below the material’s strength, viscous damper application in the minaret significantly reduces tensile stresses only in the minaret. As a result, viscous dampers are recommended for damage reduction in the minaret only. Otherwise, base isolation should be considered for reducing stress values throughout the entire mosque including the minaret. This study contributes towards the development of new seismic retrofitting methods for historic masonry buildings ‘minaret.

Experimental and numerical analysis of ballistic impat and material characterization of GFRP and Kevlar 29/epoxy composite laminate

Through experimental testing and numerical simulations, this study examines the effects of ballistic events on thin FRP composite laminated plates fabricated using a hand lay-up method. Experimental ballistic impact tests using a pneumatic gun are conducted on composite plates reinforced with woven glass and woven Kevlar 29 fibers. An advanced three-dimensional finite element model programed in Ansys/Autodyn v19.1 is employed to verify the experimental findings and analyze the ballistic perforation characteristics of the target. The crucial material constants needed for the constitutive material model used in the simulation are acquired through precise experimentation on samples prepared from the fabricated laminates. Significant agreement is observed between the FE simulations and experimental findings, particularly concerning the assessment of residual velocities of the projectile and damage pattern in the laminates. The results of this study show that when subjected to ballistic impact by a flat-ended cylindrical projectile, the thin woven FRP composite primarily experiences damage characterized by delamination, fiber breakage and matrix cracking. Additionally, based on current simulations, it is observed that the ballistic limit velocity of the Kevlar 29/epoxy laminate exceeds that of GFRP by 25.64% when both materials have an equal thickness of 2.8 mm.

New insights into the evolution mechanism of mechanical and shrinkage properties of UHPC under sustained sub-elevated temperatures

In this paper, the mechanical properties, damage pattern, mass loss, and drying shrinkage of ultra-high performance concrete (UHPC) under sustained sub-elevated temperatures (60 ℃-200 ℃) are studied. The effect of UHPC mixture, temperature levels and durations are analyzed. The performance evolution mechanism is revealed based on the analysis of hydration products and microstructures. Results show that at 150 ℃, the water loss of C-S-H gel is continuous (>90d). After sustained action at 100 ℃-200 ℃ for 3d or 7d, UHPC shows obvious expansion, which is attributed to the interlayer water evaporation of gel phase causing spacing between the gel sheets. At 60 ℃ and 100 ℃, the strength incresear and the mean chain length (MCL) decrease are associated with the increase in the SiO4 tetrahedron production in the C-S-H gel phase. At 150 °C and 200 °C, the increase of C-S-H gel’s MCL, gel phase stiffening, and pore structure refinement are important reasons for the increase in compressive strength of UHPC.

Study on damage of CRTS II slab tracks in coated-uncoated transition zones subjected to temperature and train loads

The CRTS II ballastless track is sensitive to temperature due to its longitudinal continuity. The application of reflective insulation coating can efficiently lower the temperature of the track slab, thereby decelerating track deterioration. Given the considerable length of high-speed railway lines, the application of reflective insulation coatings leads to numerous transitions between coated and uncoated sections. This study investigates the influence of reflective insulation coatings on the structural damage of coated-uncoated transition zones in railways. To this end, a CRTS II slab track model involving the bilinear cohesive zone model and the concrete plastic damage model is established. The model examines the combined impact of high temperature and train loading, aiming to investigate the damage patterns within the coated-uncoated transition zone of the track. The results indicate: (1) During high temperature loading, the center of the track slab layer is predisposed to warping compared to the sides. (2) If the cohesion parameter falls below 0.04 MPa, augmenting the cohesion model parameter effectively alleviates track slab arching. (3) In instances where the track slab lacks complete coverage of reflective insulation coatings, train loading may shift the location of the maximum vertical displacement and interface failure mode.

NATURAL EXPOSURE TO ARSENIC-INDUCED GENOTOXIC EFFECTS IN DIABETIC AND NON-DIABETIC INDIVIDUALS

Arsenic contamination in drinking water is a global health issue linked to various adverse health outcomes, including genotoxic effects. Understanding these effects in different populations, including diabetic and non-diabetic individuals, is critical for developing targeted public health interventions. Objective: This study aimed to investigate the genotoxic effects of arsenic exposure in diabetic and non-diabetic individuals residing in arsenic-contaminated and control areas. Methods: In this cross-sectional study conducted from January to June 2024, 100 participants were recruited from areas with known differences in arsenic water contamination levels. Participants were divided equally between arsenic-contaminated and non-contaminated regions, with 15 diabetic and 20 non-diabetic individuals selected from each group. A standard questionnaire was administered to collect demographic data and medical history. Additionally, 12 water samples from the contaminated area were analyzed for arsenic concentration. Genotoxic effects were assessed using the comet assay, and DNA damage was quantified using an empirical numerical rating system. Results: Significant DNA damage was observed in the blood cells of individuals from the arsenic-contaminated area compared to those from the non-contaminated area. Diabetic individuals showed similar patterns of DNA damage to non-diabetics within the same exposure group. Even in the non-contaminated group, slight DNA damage was detected, suggesting potential contributions from other environmental factors. Conclusion: The findings demonstrate that arsenic exposure is associated with significant genotoxic effects in both diabetic and non-diabetic populations. DNA damage in non-contaminated areas also indicates a possible impact of other environmental factors. These results highlight the need for ongoing monitoring and mitigation strategies to address arsenic contamination and its health impacts.