Structural Failure Research Articles

Reliability and Fire Performance of Built-up (Battened) Cold-formed Steel Columns: Numerical study

Cold-formed steel (CFS) columns play a crucial role in modern construction due to their lightweight, prefabricated, and recyclable characteristics, contributing significantly to structural safety and reliability. However, unprotected CFS columns lose their load-bearing capacity within 10-15 minutes under fire conditions. This study reviews recent advancements aimed at improving the fire resistance of CFS columns, focusing on factors such as steel thickness, grade, cross-sectional shape, and fire protection materials. Using ABAQUS software, validated against experimental data, parametric studies reveal that thicker sections and higher-grade steels enhance fire resistance, delaying structural failure. Fire protection strategies, such as plasterboard encasement, further bolster safety. The Complex cross-sectional shape demonstrated the highest load capacity (178.51 kN), while G450 steel outperformed other grades in both load capacity and fire resistance. Columns with 1.95 mm thickness provided the longest failure time (73.49 minutes).

Micro-Scale Fracture Characteristics of Emulsified Asphalt Cold Recycled Mixture Based on Discrete Element Method

Asphalt pavement often experiences structural failure due to repeated vehicle loading. The discrete element method (DEM) model was established based on the semicircle bending test (SCB) to investigate the fracture damage mechanism of emulsified asphalt cold recycled mixture (CRME) under loading. The micro-mechanical parameters of CRME were determined through a reliable validation process using the uniaxial compression static creep test. The microscopic fracture characteristics of CRME were investigated through the load-displacement curve, stress distribution, and force chain distribution. The fracture energy was used as the evaluation index to analyze the influence of prefabricated notch length and aggregate gradation on the fracture performance of CRME. The results indicate that the emulsified asphalt mortar-aggregate interface was the critical weak position of the mixture fracture; the failure of the tension chain was the main destructional form of the SCB test. The development of cracks affected the stress concentration phenomenon and stress concentration level of the mixture. Fine-grained mixture exhibited crack resistance. The number and length of cracks were affected by gradation. As the prefabricated notch length increased, the influence gradually diminished. The research results could provide theoretical and data support for the design of CRME.

Changes in properties of thermal insulations under certain environmental effects

AbstractSaving energy and reducing greenhouse gas emissions is a priority for the construction sector. Heating of buildings requires the burning of fossil fuels, which can be significantly reduced by insulating the building envelope. Nowadays, the thermal insulation of buildings is essential. There are several important, well-known data about most thermal insulation materials, but there is only negligible information about the change of their properties under installation conditions or if they are already exposed to additional stresses due to structural failures and damages. This study aimed to examine the changes in properties of three common thermal insulation materials when installed in a flat roof or facade and exposed to excess moisture due to the damage of waterproofing or façade and/or when exposed to direct strong sunlight.

Theoretical and experimental study on the mechanical measurement of rock tensile fracture by ring radial compression

Conventional Brazilian disc splitting tests are hampered by stress concentration at the loading points, leading to test outcomes that do not truly represent the engineering failure strength of rocks. To enhance the accuracy of these tests, the specimen shape has progressed from the Brazilian disc to a circular ring. This study presents a theoretical analysis of the compression deformation process in circular rings, followed by platform-radial compression tests conducted on various types of rocks and metals, employing the digital speckle correlation method alongside an improved mechanical extensometer. The findings indicate that circular ring specimens failed under a combination of tensile and compressive stresses. The main crack originates along the loading direction on the inner wall of the ring and propagates outwards, resulting in the failure of the entire ring structure. While maximum tensile strain may serve as an indicator of rock failure, tensile stress alone should not be considered a definitive criterion for failure.

Comparative analysis of armid fiber reinforced polymer for strengthening reinforced concrete beam‐column joints under cyclic loading

AbstractThis research investigates the structural performance and failure mechanisms of beam‐column joints reinforced with aramid fiber‐reinforced polymer to bolster the durability and seismic resilience of concrete structures. It meticulously selects and proportions materials such as ordinary Portland cement Grade 53 cement, fine and coarse aggregates meeting IS: 383–1970 standards, and water conforming to IS: 456–2000 specifications. Tests confirm the high quality of ordinary Portland cement, crucial for optimal beam‐column joint performance, while carbon fiber‐reinforced polymer enhances structural integrity with its lightweight composition and substantial tensile strength (3800 MPa–4200 MPa). Failure analysis reveals that non‐aramid fiber reinforced polymer wrapped beam‐column joint specimens predominantly failed due to concrete crushing, whereas aramid fiber‐reinforced polymer‐wrapped specimens failed due to fracture in the aramid fiber‐reinforced polymer composite, emphasizing stress concentration areas. This study underscores the pivotal role of stress distribution in failure mechanisms and underscores the significance of robust reinforcement design in bolstering structural resilience. These insights advance retrofitting strategies and reinforce techniques aimed at enhancing the longevity and seismic resistance of concrete structures.

Minimizing Polymer Curl Distortion and Heat Impact to Improve Digital Light Processing Printing Accuracy via Subdivision Method

Curl distortion has been a persistent challenge for vat photopolymerization‐based printing technology such as digital light processing (DLP), leading to structural deformation and print failures. This study presents a new approach to mitigate curling distortion and heat effects during DLP printing by dividing the printing layer image into sequential subimages, using a breadth‐first search algorithm. The progressive curing process, resembling a ripple pattern, results in a significant improvement in printing accuracy. The deviation is reduced tenfold when the layer image is divided into subimages with 10 pixels for a 32 mm diameter disc. Additionally, subdivision strategy helps to reduce the heat effect during photopolymerization, as monitored in situ by a long‐wave infrared camera. The successful reduction of residual stress using the subdivision strategy results in a 75% improvement in the mechanical performance of the printed products. The simple adoption of subdivision strategy in practical 3D printing applications is also demonstrated. For solid 3D printing structures, introducing intervals within the solid printing layers—such as using a grid structure instead of a fully solid one, can help to reduce curling and heat effects, thereby improving 3D printing accuracy.

A Case Study on Using the Concrete Cover Block in Steel Reinforcement Bar: Ghorahi Dang, Nepal

Cover block is one of the basic component on building structure like slab, column, beam, foundation. It is a multi- functionary engineering material. In maximum construction sites, bricks, stones, steel bars are used instead of cover block. This brings a lots of depraved consequences on building structures like lack of well spacing between surface and reinforcement bars, unbalance position of steel bars, reduce the lifespan of building and corrosion. Here, the main function of cover block is to reinforce the building structure by avoiding the corrosion on steel bar or avoiding the moisture with the steel bar, providing the resistive property, distributing an uniform load and managing space. In this way, the cover block is attached in a reinforcement bar in order to reinforce a building structure. When cover block was applied in a building structure, it made a building more durable as well as more attractive by maintaining the shape. This observation suggests that the use of cover block can contribute in strengthening a building structure and maintaining a position and space of a reinforcement bars as well as a structure. Key Words: Concrete cover block, Reinforcement bar, Potential failure of structure, Space maintaining, Corrosion activity.

Epidemiological profile of bronchial lung cancer between the years 2013 to 2023 in the northern region of Brazil

Lung and bronchial cancer is one of the leading causes of death in Brazil, with higher incidence among men, although the number of cases in women is increasing. Smoking is the main risk factor, but late diagnosis worsens disease progression, especially in marginalized regions like the North of the country. Therefore, this study aimed to analyze the evolution of lung and bronchial cancer cases in the North region of Brazil over the past ten years. Data were collected from the Department of Informatics of the Unified Health System (DATASUS) and the oncology panel, organized by age group, sex, and state. Analyses were conducted using RStudio and Excel. The state of Pará showed the highest increase in lung and bronchial cancer cases in 2023, followed by Rondônia and Amazonas, which recorded significant increases in 2021. A rise in cases was observed with advancing age, especially among men. The results suggest that delayed diagnosis, combined with the precariousness of the healthcare infrastructure in Northern Brazil, may contribute to disease progression and increased mortality. The marginalization of this region in the national healthcare context is a relevant factor in this scenario. It is concluded that delayed diagnosis and structural failures in the healthcare system are key determinants of the increase in lung and bronchial cancer cases in the North region, and that structural measures are necessary to improve early diagnosis and reduce mortality.

Time-Dependent Stress Drop Variations After Large Earthquakes Along the North Chilean Megathrust

ABSTRACT We observe a time dependence of the median stress drop in spatiotemporal proximity of large earthquakes. The median stress drop of the early aftershock seismicity is elevated for only a few days after the mainshocks and then rapidly falls back to the long-term average. This short-term variation has remained largely unnoticed by previous studies, presumably due to their usually low temporal resolution. Our study uses a recent extensive stress drop catalog, which contains more than 51,000 events from northern Chile. It includes observations from three Mw>7 megathrust earthquakes, namely the 2007 Mw 7.7 Tocopilla earthquake, the 2014 Mw 8.1 Iquique earthquake, and its largest Mw 7.6 aftershock, as well as another eleven Mw>6 earthquakes. A detailed analysis reveals that the elevated stress drop is not primarily linked to an increase of seismic moment during the early aftershock phase but is rather attributable to higher measured corner frequencies in the corresponding time interval. We propose two possible explanations: (1) The high stress changes induced by the mainshock allow failure of strong structures at or adjacent to the main rupture area, which produces higher stress drop events. After a few days, afterslip activity has reduced the in situ stresses and thereby the failure potential of the stronger regions. (2) The mainshock disturbs the fluid-sealing plate interface, allowing overpressured fluids to escape, exhibiting the so-called fault-valve behavior. The effect appears to persist only for several days until the sealing effect is restored and average stress drop levels are recovered.

Prediction of the Mean Time to Failures of a Complex System Using the Monte Carlo Simulation Method

This paper presents a Monte Carlo-based algorithm for predicting the Mean Time to Failure (MTTF) of complex structures, specifically a “Bridge-type network” with five elements exhibiting various failure distributions. The proposed algorithm involves generating element lifetimes through the inverse of their failure distribution functions, providing a robust approach to evaluating MTTF for systems beyond traditional series or parallel configurations. The approach was implemented in MATLAB, and the software underwent extensive testing across different scenarios, including both exponential and Weibull distributions. The results demonstrated the method’s accuracy and its capability to handle diverse failure distributions with minimal error. This tool offers reliability engineers a versatile solution for predicting and improving the reliability of complex systems. In summary, the proposed method and software significantly advance the reliability assessment of intricate structures and offer a solid foundation for further research and practical applications in the field of reliability engineering.

Structural Health Monitoring and Failure Analysis of Large-Scale Hydro-Steel Structures, Based on Multi-Sensor Information Fusion

Large-scale hydro-steel structures (LS-HSSs) are vital to hydraulic engineering, supporting critical functions such as water resource management, flood control, power generation, and navigation. However, due to prolonged exposure to severe environmental conditions and complex operational loads, these structures progressively degrade, posing increased risks over time. The absence of effective structural health monitoring (SHM) systems exacerbates these risks, as undetected damage and wear can compromise safety. This paper presents an advanced SHM framework designed to enhance the real-time monitoring and safety evaluation of LS-HSSs. The framework integrates the finite element method (FEM), multi-sensor data fusion, and Internet of Things (IoT) technologies into a closed-loop system for real-time perception, analysis, decision-making, and optimization. The system was deployed and validated at the Luhun Reservoir spillway, where it demonstrated stable and reliable performance for real-time anomaly detection and decision-making. Monitoring results over time were consistent, with stress values remaining below allowable thresholds and meeting safety standards. Specifically, stress monitoring during radial gate operations (with a current water level of 1.4 m) indicated that the dynamic stress values induced by flow vibrations at various points increased by approximately 2 MPa, with no significant impact loads. Moreover, the vibration amplitude during gate operation was below 0.03 mm, confirming the absence of critical structural damage and deformation. These results underscore the SHM system’s capacity to enhance operational safety and maintenance efficiency, highlighting its potential for broader application across water conservancy infrastructure.

Parametrized fragility, failure analysis and cost-effectively strengthening of electrical power distribution system under ice and concurrent wind hazards

In the past decades, the increasing frequency and severity of winter storms due to climate change have revealed the vulnerability of power systems against such events. This study aims to investigate the impact of ice and concurrent wind hazards on power systems by proposing a set of parametrized fragility functions for utility poles and conductors, and then applying them to system failure analysis and cost-effectively strengthening. The fragility model is generated by logistic regression to estimate the failure probability of poles and conductors as a function of hazard and structural characteristics. Applying proposed functions, system failure analysis is performed using IEEE123 testbed in four cities with various hazard characteristics. The results show that wind speed significantly affects pole rupture, while extreme ice and wind combination influences conductor breakage. Meanwhile, even minor structural failure leads to severe outages. Moreover, the risk-based Expected Outage Reduction (EOR) is calculated with developed fragility models as pole replacement ranking index. By comparing different replacement strategies, the 70-year system performance can be cost-effectively optimized by risk-based pole ranking and replacement pace and timing. Overall, the models and applications presented in this paper serve as a critical part of power system resilience analysis against winter-related hazards.

Experimental study on seismic damage of SRC-RC vertical hybrid structure

In order to analyze the seismic performance of the SRC-RC vertical hybrid structure, three substructure models were designed, and the key data of structural performance, such as hysteresis curve, skeleton curve, bearing capacity, energy dissipation of structure, residual deformation and damage degree were obtained by carrying out low cyclic loading tests. According to the tests, the plastic development at the column base was delayed because of the reinforcement of section steel, and the plastic development at beam end was much more sufficient, which benefited the beam hinge mechanism in the transition area, so that the transition area has better energy dissipation capacity and deformation capacity. Based on the more sufficient lateral displacement of beam hinge, the beams suffered bending deformation obviously, and interaction between the beams and the infilled wall was significant, which led to a more complex interface force transmission, so the bending cracks and the shearing cracks were densely distributed along the full length of the beam. Meanwhile, the reinforcement of section steel not only improved the deformation capacity of the models but also resulted in more significant damage difference in positive and negative loading. To quantitatively evaluate the damage level, a seismic damage index system was proposed, including displacement damage degree, bearing capacity damage degree and residual deformation index, which reflect the increment of deformation caused by structural damage, the deterioration of bearing capacity and the residual deformation, respectively. It is suggested that the structural failure should be defined respectively under different modes: For the strength degradation behavior mode and ductility behavior mode, structural failure should be confirmed if the load reduces to 0.90 and 0.85 times of the peak load, respectively; and for the brittle behavior mode, the frame is considered to fail when the load reaches the peak without considering the structural performance after the peak load.

Experimental prototype of mesh antenna based on digital twin technology

The ring mesh antenna plays an important role in the field of aerospace communication owing to its excellent performance characteristics, but faces the challenge of decreasing profile accuracy due to environmental and structural failures during in-orbit operation. Digital twin, a promising technology, can effectively monitor and adjust the antenna surface accuracy. In other words, by creating a digital model of the physical entity, real-time monitoring and adjustment can be made to maintain the electrical performance of the antenna. In this paper, a digital twin system for an experimental prototype of a ring mesh antenna is proposed. Firstly, we introduce the preliminaries of digital twin technology. Secondly, we propose a system framework based on a five-dimensional digital twin model. Then, a digitization software and a visualization interface are developed. Finally, according to efficiency analysis and simulation results, the feasibility of the system was verified. We demonstrate its effectiveness in terms of real-time monitoring and automatic mesh adjustment functions, and significantly improve the efficiency of the adjustment process. It provides a reference with significant value for the application of digital twin technology in the field of aerospace communication, which significantly advances the development of this field.

Potential of water-soluble chitosan Schiff bases extracted from Metapenaeus dobsoni shells as effective corrosion inhibitors

Corrosion causes significant economic losses and structural failures in industries, highlighting the need for eco-friendly inhibitors. Chitosan (CS), a biodegradable and non-toxic biopolymer, shows potential, though its limited water solubility restricts its applications. To overcome this challenge, this study presents the synthesis of two water-soluble chitosan Schiff bases (CSBs) derived from the shells of Metapenaeus dobsoni (M. dobsoni). The extracted CS exhibits a remarkable degree of deacetylation exceeding 95 %, which was subsequently modified through reactions with o-vanillin (2-hydroxy-3-methoxybenzaldehyde) (CSB I) and 2,3-dihydroxybenzaldehyde (CSB II). Structural characterization using spectroscopic techniques confirmed the successful formation of CSBs. Electrochemical measurements were employed to assess the corrosion resistance of mild steel in 0.5 M HCl with varying concentrations of CSB I and CSB II. The results revealed superior corrosion inhibition by CSB II (% IE = 94.48 %) compared to CSB I (% IE = 88.80 %). The methoxy group in CSB II contributed to its higher electron density and enhanced adsorption, leading to better surface coverage and corrosion resistance. Both inhibitors followed the Langmuir isotherm, suggesting a mix of physisorption and chemisorption. These CSBs are promising for corrosion control in industries like pipelines, storage tanks, construction materials, and acid pickling.

Numerical Investigation of the Cohesive Strength Regime of the Bilobated Arrokoth after the Sky-crater-forming Impact Event

In 2019, NASA’s New Horizons mission, using the Long Range Reconnaissance Imager, revealed Arrokoth’s bilobated shape and a large impact-crater-like region (“Sky”) on the small lobe, which is ∼7 km wide and ∼1 km deep. Given that this depression takes up ∼7% of the entire volume of the small lobe, Arrokoth’s neck, the most structurally sensitive area to failure, might have been subject to substantial structural modification if the Sky-crater-forming event occurred after the bilobate shape had formed. Using the π-scaling law, we quantified the linear momentum imparted to the small lobe by the Sky-crater-forming event, which was in the range of (2.4–4.0) × 1013 kg m s−1, depending on Arrokoth’s bulk density of 250–500 kg m−3 and impact speeds of 100 m s−1, 300 m s−1, and 1 km s−1. If the linear momentum was fully transferred to Arrokoth’s small lobe, it would have given the small lobe an impulse velocity of approximately 0.1 m s−1 relative to the large lobe. To assess the structural impact of this event, we used a finite-element modeling approach to simulate post-impact stress fields driven by the estimated impulse velocity on the small lobe and constrained the critical cohesive strength required to prevent structural failure. Based on the current parameter space, our results suggest that the Sky-crater-forming event could have required the critical cohesive strength of up to ∼20 kPa for Arrokoth’s neck to avoid structural failure, which is higher than the typical cohesive strength estimated for small bodies (usually less than 1 kPa for asteroids and comets).

Vibration Analysis of the Bow Bridge With and Without the Soil Foundation

Abstract. Earthquakes can impart the phenomenon of resonance, where the frequencies of seismic waves align with a bridge's natural frequency, causing amplification of vibrations that can lead to structural failures. Aiming to accurately predict potential vulnerabilities posed to the bridge when subjected to earthquakes, this research presents a vibration analysis of the Bow Bridge. Two models, which simulate the Bow Bridge with and without soil foundation, are conducted to investigate the bridges natural frequencies and mode shapes under soilless and soiled conditions. The research result shows that the average vibration frequency in a soiled environment is much lower than that in a non-soil environment, intuitively proving the mitigation of soil environment to bridges vibration frequencies. Based on the agreeable data output, this research demonstrates the feasibility of modeling in the prediction of practical construction.

Modeling and analysis of creep at elevated temperature analysis on thin-walled profile structures

Abstract High-strength steel plays a crucial role in aerospace because of its excellent performance. The high temperatures experienced during a spacecraft’s re-entry to Earth may result in creep in the steel, potentially leading to structural failure, so the finite element software is utilized in this paper to establish a calculation model and analyze the impact of temperature and fire duration on the creep strain of high-strength I-section steel beams under elevated temperatures. Among them, the high-temperature parameter significantly affects the creep strain variation of the mid-span element of the high-strength I-section steel beam. When the temperature parameter is increased by 100%, the maximum creep strain variation of the mid-span component of the beam will increase by about 24%. Under the exact increase, the maximum creep strain variation of the high-temperature duration parameter will only increase by about 3.78%; thus, when conducting a high-strength steel structure, fire resistance analysis should mainly consider the influence of temperature on its creep at elevated temperature strain.

Blast response and protection level of concrete composite wall panels made with recycled tyre fibres in a cement matrix

This paper investigates the blast response and protection level of a new blast-resistance wall panels made of Recycled Tyre Fibres Concrete (RTFC) as an exterior protective layer compositely connected to a concrete wall through experiments and numerical modelling. RTFC is a novel sustainable cement-based versatile composite, made with recycled non-biodegradable material (tyre rubber particles) in the form of composite fibres in a cement matrix, with applications in blast and ballistic protection that features high dynamic properties. Three composite wall panels were constructed and subjected to blast loads generated by Advanced Blast Simulator (ABS). Three different loading scenarios, each with an intensity capable of causing complete structural failure, were applied. The blast wave characteristics, such as the imposed overpressure and impulse, were measured alongside the deflection of the specimens. The wall specimens could withstand the blast loads with minimal damage. No cracks were observed in the RTFC layer, with only minor cracks appearing on the concrete side of the wall. The protection performance of the wall specimens was examined following UFC guidelines, revealing their outstanding resistance to blast loads. Moreover, in line with these guidelines, the composite wall panel is eligible for a High Level of Protection (HLoP) classification. Finally, a Single Degree of Freedom (SDOF) analytical model was developed for the wall panel to determine the Dynamic Increase Factor (DIF) of RTFC. The analysis resulted in a DIF value of 1.5, which was then incorporated into the numerical models of the walls. The accuracy of the DIF was validated by comparing the numerical results with experimental data, confirming its reliability.

Evolution of mechanical behavior in granular soil during fine particle loss simulated by salt dissolution: Insights from ring shear tests

Fine particle loss in soil is one of the main causes of slope instability and geotechnical structure failure. Loss of fines can cause instability in granular assembles by changing the fabric and microstructure of the sample. However, real-time monitoring of the evolution of mechanical behavior in granular soils during the particle loss process is still poorly explored. This study presents a novel approach by simulating fine particle loss through salt dissolution in ring-shear tests, offering real-time insights into the mechanical evolution of granular soils under realistic stress conditions. Meanwhile, the shear resistance, shear displacement, vertical displacement, salt content, and acoustic emissions were simultaneously recorded. The test results showed that the instability of the sample was triggered by the loss of fine particles. With a gradual loss of fine particles, both the vertical and shear deformations and the void ratio increased. The evolution of shear resistance in the sample can be divided into three stages: stress weakening, then strengthening, and finally recovery to the initial value. We infer that the evolution of shear resistance originated from the collapse and rearrangement of its granular fabric and microstructure. Additional evidence for this hypothesis was provided by high-frequency acoustic emissions (approximately 150 kHz), suggesting buckling of the force chains accompanying the particle loss process. Furthermore, the sample experienced greater shear deformations and stress weakening that developed under a larger initial fine content or a higher normal stress. This finding may provide valuable insights into the mechanical behavior of granular soil during the fine particle loss process.