Failure Modes Research Articles

Evaluation of the Validation Process of Prospective Recipients of Educational Scholarships on the Siaplah Platform: A Case Study at The West Kalimantan Provincial Education and Culture Office

This study aims to evaluate the validation process of prospective recipients of educational scholarships through the Siaplah platform implemented by the West Kalimantan Education and Culture Office. The research methods used in this study are Business Process Improvement (BPI) and Failure Mode and Effects Analysis (FMEA). Because BPI can evaluate in aligning processes with organizational goals and strategies. In the context of this research, BPI can assist the West Kalimantan Education and Culture Office to ensure that the scholarship validation process supports the achievement of organizational goals related to education. Meanwhile, FMEA is used to identify potential risks, failures, and weaknesses in the validation process. Through this analysis, research can identify critical points in the process that could lead to failures or problems. So the FMEA can be improved by giving a score on each risk and impact. Research results: Business process recommendations for prospective PBP recipients are made based on the design of business process improvement that has been carried out using the Business Process Improvement (BPI) method. Some activities have changed, activities that have been added to activities that have been removed. From the results of simulations carried out on the current business process (as it is) and business process recommendations (to be), it was found that the increase in time analysis reached 02.8% in the business process of prospective PBP recipients, 1.44% in the implementation of the business of prospective PBP recipients, and 1.55% in the business evaluation of prospective PBP recipients.

Experimental study on seismic performance of glulam structural columns with anchored connections

In current timber structures, the low initial stiffness, and weak bending resistance of the connections result in significant structural deformation and failures. To improve the mechanical capabilities of timber structural joints, a novel timber-component anchorage system with robust bending resistance was introduced. Thirteen scaled-down specimens of glulam columns with anchored connections were meticulously fabricated for testing, scaled at a ratio of 1/2. Cyclic loading tests were conducted, considering three types of the volume compression percentage of confined wood perpendicular to the grain; and five axial-load levels. Subsequently, various seismic performance aspects of glulam columns with anchored connections were examined, including the failure mode, hysteresis behavior, envelope curve, strength degradation, stiffness degradation, energy dissipation capacity, and critical points. During the analysis, the influence of the P–Δ effect on the results was discussed and a damage-based hysteretic model was presented. Finally, a comparison of the mechanical performance for various types of timber structural joints was conducted. The findings revealed that the failure mode of the anchored glulam columns occurred as cracking perpendicular to the grain, and the anchored columns exhibited superior bending resistance and overall seismic performance.

Experimental Study on Quick‐Locking Reinforcement Model for Local Defects in Pipelines in the Rich Water Area

ABSTRACTThe management of local defects in municipal pipelines in water‐rich areas remains a significant challenge, particularly under high‐pressure conditions. This study investigates the performance of quick‐lock steel sleeves as a trenchless repair method through full‐scale experiments on five different pipeline diameters. The experiments focus on the failure modes and critical buckling pressure of the sleeves under external pressure. A novel design model based on structural reliability theory was developed and validated against experimental results. The results show a close match between the calculated and experimental buckling pressures, with a ratio ranging from 0.87 to 1.15. These findings provide valuable insights for the design and application of quick‐lock sleeves in high‐pressure municipal networks. This study contributes to improving the reliability and effectiveness of pipeline repair technologies, offering practical solutions for addressing pipeline leakage and instability in challenging environments.

Clayey soil stabilisation with geopolymerized olivine and glass fibers

In some engineering applications soil stiffness only could not be a reliable parameter in accordance with specific standardizations especially when dealing with dynamic loading. In other words, foundation soil should be altered regarding its ductility in order to prevent sudden damage due to brittleness. Plenty of researchers were concerned to focus on soil reinforcement using glass fibers. Besides, the alkaline activation method has been adapted to alter the strength properties of soft soil. Furthermore, recent alkaline activation of soft soil, using olivine and Potassium hydroxide, coupled with soil reinforcement was adapted to change the post-peak behavior of soft soil. The aim was towards ultimate strength increase and enhancement of failure mode. In this research, geopolymerized soil and geopolymerized reinforced soil were cured for 7, 28, 90 and 180 days respectively. Compressive stress tests were conducted on both mixtures namely SO and SOG samples. Results drawn from the tests revealed a drastic increase in compressive strength for SO samples cured for 28 and 90 days, namely 3,64 MPa and 7,5 MPa respectively. Though a sharp drop was seen when approaching failure. With the addition of reinforcing glass fibers for the suggested curing regimes the failure mode was enhanced to become more ductile.

An innovative multilayered material fabricated through additive manufacturing for structural applications: method and mechanical properties

Abstract Additive manufacturing (AM) is a cost-effective method for fabricating structurally sound components. Fused filament fabrication (FFF) is a popular AM technique known for its design flexibility, minimal material wastage, and recyclability. Poly lactic acid (PLA) is a thermoplastic widely used in aerospace, biomedical, and automobile industries. Wood-PLA, incorporating wood fillers into PLA, finds applications in several industries. This research explores multilayered materials (MLM) for enhanced performance in various sectors such as aircraft, energy, and biomedical. Mechanical properties of MLM were investigated under different load conditions (tensile, bend, compressive). Properties simulated through Finite Element Method (FEM) showed minimal error (less than 1 %). Microscopic analysis, aided by scanning electron microscope (SEM) fractography, reveals a brittle mode of failure in the specimens. This study provides valuable insights into the mechanical behaviour of MLM, offering potential applications in diverse industries.

Finite-element investigations on the influence of material selection and geometrical parameters on dental implant performance

Abstract Dental implants provide functional and aesthetically pleasing dental replacements, but their longevity depends on biomechanical factors, physical characteristics, and patient variability. The present study used finite-element analysis to reveal the biomechanical response and potential modes of failure of dental implant systems subjected to normal occlusal loads. A generalized comparative assessment was carried out to measure the effect of the choice of crown material with zirconia, porcelain-fused-to-metal, and ceramic crowns. Such simulations showed complex patterns of stress distribution and deformation in the implant assembly with significant variation due to the mechanical properties of the crown material. Stiffer zirconia crowns magnified stress concentrations by 12.6, 10.8, 11.4, and 9.1% in the implant fixture, crown, cortical bone, and cancellous bone, respectively, compared with more compliant ceramic crowns. Furthermore, the maximal deformation of both the cortical and cancellous bone induced by zirconia crowns was higher by 21.1 and 19.2%, respectively, compared with the ceramic crowns. These results emphasize that the crown material properties are significant for controlling and modulation biomechanical load transfer, which plays a decisive role in the long-term durability and resistance to failure mechanisms such as interfacial debonding, bone resorption, and fatigue cracking. This study provides valuable information for optimizing implant designs and material selection that may improve clinical results, positively affecting patient satisfaction with dental implant therapy.

Investigating the Mechanical Characteristics and Fracture Morphologies of Basalt Fiber Concrete: Insights from Uniaxial Compression Tests and Meshless Numerical Simulations

To explore the mechanical properties and fracture modes of basalt fiber-reinforced concrete, single-doped and hybrid-doped basalt fiber-reinforced concrete was prepared, and uniaxial failure tests under different basalt fiber-reinforced concrete contents were carried out. At the same time, the smooth kernel function in the traditional SPH method was improved, and the basalt fiber random generation algorithm was embedded in the SPH program to realize the simulation of the progressive failure of basalt fiber-reinforced concrete. The results show that under the circumstance with no basalt fiber, the specimen final failure mode is damage on the upper and lower surface, as well as the side edge, while the interior of the specimen center is basically intact, indicating that there is an obvious stress concentration phenomenon on the upper and lower surface when the specimen is compressed. Under the circumstance with basalt fiber, longitudinal cracks begin to appear inside the specimen. With the increase in the content, the crack location gradually develops from the edge to the middle, and the crack number gradually increases. This indicates that appropriately increasing the fiber content in concrete may improve the stress state of concrete, change the eccentric compression to axial compression, and indirectly increase the compressive strength of concrete. The numerical simulation results are consistent with the test results, verifying the rationality of the numerical simulation algorithm. For the concrete model without the basalt fiber, shear cracks are generated around the model. For the concrete model with basalt fiber, in addition to shear cracks, the tensile cracks generated at the basalt fiber inside the model eventually lead to the splitting failure of the model. The strength of concrete samples with basalt content of 0.1%, 0.2%, and 0.3% is increased by 1.69%, 5.10%, and 4.31%, respectively, compared to the concrete sample without basalt fiber. It can be seen that with the increase in the content of single-doped basalt fiber, the concrete strength is improved to a certain extent, but the improvement degree is not high; For hybrid-doped basalt fiber-reinforced concrete, the strength of concrete samples with basalt content of 0.1%, 0.2%, and 0.3% is increased by 14.51%, 15.02%, and 30.31%, respectively, compared to the concrete sample without basalt fiber. Therefore, compared with the single-doped basalt fiber process, hybrid doping is easier to improve the strength of concrete.

Enhancing Shear Strength of Weakly Consolidated Mudstone in Water-Diversion Tunnels Through Artificial Ground-Freezing Techniques: An Experimental and Theoretical Study

The utilization of artificial ground-freezing techniques is increasingly prevalent in the construction of water-diversion tunnels. The inadequate mechanical properties of weakly consolidated mudstone (WCM) pose significant challenges for tunneling construction. In this study, a series of triaxial shear tests were conducted on frozen specimens of WCM to elucidate its shear strength characteristics. The experiment involved four freezing temperatures (0, −5, −10, and −20 °C) and four confining pressures (1, 2, 3, and 4 MPa). The results indicate that the shear failure mode of the WCM exhibits distinct shear zone failure characteristics under artificial freezing conditions, particularly prominent in the lower temperature environments. As the freezing temperature gradually decreases, there is a substantial increase of over 200% in the shear strength of frozen specimens, accompanied by a corresponding decrease in yield strain. Furthermore, the cohesion and internal friction angle of frozen WCM increase as the freezing temperature decreases, following a complex exponential function relationship rather than a linear one. As the freezing temperature decreases from 0 °C to −20 °C, there is an increase in cohesion and internal friction angle from 1012 kPa to 1425 kPa, accompanied by a rise in the internal friction angle from 43.2° to 58.1°. Notably, the application of confining pressure exerts a pronounced influence on the shear strength of frozen WCM, with elevated levels of confining pressure resulting in a substantial augmentation of the shear strength. The failure mode of frozen WCM is significantly influenced by freezing temperatures. At low temperatures, the specimen of mudstone exhibits a shear failure behavior, while at high temperatures, it predominantly demonstrates expansion failure. This phenomenon can be attributed to the increased brittleness of specimens caused by ice crystals, rendering it more susceptible to brittle failure under shearing forces. These findings signify an enhancement in the mechanical behavior of WCM within the tunnel sidewall under artificial freezing conditions.

Monitoring a mass timber—BRB braced mass timber frame under cyclic loading via acoustic emission

This article focuses on the acoustic emission (AE) monitoring of a new type of mass timber buckling restrained brace (T-BRB), consisting of a wood casing made of mass plywood panel and a steel core embedded in the casing, for improving seismic resilience of mass timber structures. The casing secures the steel core through a series of bolts. To investigate the failure mechanisms of T-BRBs, two cyclic loading tests are conducted on a mass timber frame braced by T-BRBs with and without carbon fiber-reinforced polymer wraps, and an AE system is deployed for structural health monitoring (SHM). Multiple AE signatures are analyzed to infer the yielding point and failure modes of the T-BRB. AE features, including AE hit rate and cumulative energy, can successfully identify the ultimate structural failures. Results from AE hits and measured area of rectified signal envelope (MARSE) per quarter cycle suggest that the first significant feature values correspond to the cycle when the embedded steel core yielded. The b-value analysis demonstrates a general decreasing trend through the loading process and can characterize the evolution of structural damages. By evaluating both the strain energy and AE energy to reflect damage severity, the sentry function can identify the load cycle of steel core yielding and ultimate structural failure. As the first work applying AE monitoring on structural experiments of T-BRB, this research provides general guidances for SHM of T-BRB braced mass timber structures.

Which failures do patient-specific quality assurance systems need to catch?

The Joint AAPM-ESTRO TG-360 is developing a quantitative framework to evaluate treatment verification systems used for patient-specific quality assurance (PSQA). A subgroup was commissioned to determine which potential failure modes had the greatest risk to treatment quality and safety, and therefore should be evaluated as part of the PSQA verification. To create an extensive database of potential radiotherapy failure modes that should be detected by PSQA and to determine their relative importance for maximizing treatment quality. The subgroup consisted of eight physicists from seven countries, including representatives from three international quality assurance groups. We collected error reports from RO-ILS, SAFRON, AAPM TG publications, and other literature, including international audits. We focused on the subset of failure modes that impact whether the planned dose matches the dose received by the patient. We performed a failure-mode-and-effects analysis (FMEA), estimating the severity (S), occurrence (O), and detectability (D) of each failure mode. Detectability was scored assuming that PSQA was not done but other routine clinical QA was performed, which allowed us to see the importance of PSQA for detecting each specific failure mode. We analyzed the risk priority number (RPN=O*S*D), O*S, and severity rankings to determine the priority of each failure mode. We collected 394 error reports, which we categorized into 33 failure modes that underwent FMEA. Five failure modes were in the top ranks for both RPN and O*S analysis: four involving treatment planning system (TPS) commissioning and one regarding patient model errors. The highest-ranking RPN failure modes were: TPS algorithm limitations, TPS commissioning errors [multileaf collimator (MLC) modeling, output factor, percent-depth-dose/tissue-maximum-ratio (PDD/TMR), off-axis factor], and patient weight variation. The highest O*S failure modes were similar, with the addition of external patient position variation and incorrect linear accelerator isocenter and cGy/monitor units calibration. RPN and O*S analyses prioritized failure modes that impacted multiple patients with high occurrence and detectability scores, while severity analysis gave higher priority to single-patient modes with high severity scores. The highest-ranking severity modes were MLC sequence deletion, collision, and TPS isocenter incorrect. We have developed a list of failure modes critical to be detected during PSQA and ranked them in order of importance. The top failure modes emphasize the importance of utilizing a variety of treatment verification systems for PSQA, from secondary dose calculation through in-vivo dosimetry, in order to detect all possible errors. For failure modes in the top quartile, PSQA is critical. Without adequate PSQA, these errors may go undetected unless caught by an external audit. This analysis can be useful for optimizing PSQA workflows and for designing evaluations of treatment verification systems, and will be used by the Joint AAPM-ESTRO TG-360 to determine an appropriate validation strategy.

A sex-specific comparison of valve-in-valve transcatheter aortic valve implantation

Abstract Introduction Valve-in-valve (ViV) transcatheter aortic valve implantation (TAVI) is a viable and less-invasive alternative to open heart surgery in selected patients with bioprosthetic valve dysfunction. Since patients receiving initially a new bioprosthetic aortic valve are predominantly male, data on a sex-specific comparison of ViV-TAVI is scarce. Thus, we compared patient characteristics, procedural outcomes, and 1-year outcomes of female (F) versus male (M) patients with failing bioprosthetic aortic valves undergoing ViV-TAVI. Methods A total of 375 Patients at 3 German centres were included in this analysis. The 1-year mortality was the primary outcome measure, secondary outcomes included VARC-3 defined technical and device success and early safety. Results Overall, 160 (42.6 %) women and 215 (57.4 %) men were included. Women were older (F 81 (77; 84), p < 0.001), had a greater surgical risk (STS PROM F: 9.1 (6.1; 13,9) %, p < 0.001) and a higher rate of previous coronary bypass surgery (F: 25.6 % vs M: 40 %, p = 0.004), while presenting mostly failed valve sizes < 20 mm (F: 59.4 % vs M: 33.4 %, p < 0.001) and therefore higher gradients (F: 40 (31; 50) mmHg vs M: 32 (25; 42) mmHg, p < 0.001). Aortic regurgitation was the mode of failure in 7.5 % of F vs. 14.4 % of M. The number of stentless valves was higher in men (F: 8,1 % vs M: 14 %, p = 0.08). Patients received a self-expanding TAVI prostheses in 79.4 % and 75.8 % respectively in F and M patients. The rates of technical success (F: 75.6 % vs M: 83.3 %, p =0.06), device success (F: 52.5 % vs M: 58.2 %, p = 0.27) and early safety (F: 67.5 % vs M: 67 %, p = 0.91) were comparable between genders. Residual mean gradients were higher in F (F: 15 (11;22) mmHg vs M: 15 (10; 20) mmHg, p = 0.03), while the rates of residual regurgitations were greater in M patients (F: 1 (0.6 %) vs M: 11 (5.1 %), p = 0.04). The Kaplan-Meier estimated 30-day mortality rate (F: 2.5% vs M: 3.3%, p = 0.66) and 1-year mortality rates (F: 10 % vs M: 92.6 %, p = 0.37) were comparable between genders. Conclusion: F and M patients treated by ViV-TAVI have comparable short-term outcomes according to VARC-3-defined endpoints and similar mortality rates after 30 days and 1 year. The residual gradients in F and residual regurgitations in M could be explained by structural features of their failed valves. Further large scale studies are needed to determine, if such procedural outcomes are truly sex-specific.

A multicriteria decision-making model for risk management in an integrated management system

PurposeThis paper proposes a multicriteria model for risk management to identify and assess risks associated with an integrated management system (IMS). The main benefit of the proposed model is its systemic and logical visualization, which may facilitate the understanding of this proposal’s practical application.Design/methodology/approachThe research design consists of four stages: (1) conduct a literature review to establish risk management models in IMS; (2) collect data concerning risk management models in IMS from a large multinational automotive company; (3) propose a multicriteria model to define and assess risks as well as prioritize mitigation actions and (4) apply the proposed multicriteria model to the data collected in case-based research to evaluate the practical viability of the model to contribute to methods traditionally used.FindingsThe results showed that the proposed risk management model contributes to more reliable decision-making in an IMS. The application of the proposed model identified 85 risks in the total processes of the IMS, 31 of which were classified as high risk; thus, priority actions to be taken were defined. The risk classification and prioritization facilitated the implementation of measures to mitigate or eliminate risks, as pointed out by the company managers.Research limitations/implicationsOne of the limitations is the fact that specific knowledge is required to maintain and update the multicriteria decision-making tool used in this study. Another one implies the approach to managing risks under the different ISO standards and sector-specific requirements, since this may require updates and customization of the proposed risk management model.Practical implicationsThe implementation of IMS in contemporary business environments can be supported by a robust risk management approach. In addition, it provides the leadership with a holistic view of multiple aspects related to a company and fosters continuous improvement.Social implicationsThe social implications of this study are assessed indirectly. This study contributes to the improvement of company management models.Originality/valueTraditionally, the methods used for risk management in IMS are usually applied independently of techniques such as failure mode and effect analysis. The model developed in this work enables to manage risks continuously to achieve a systemic view of organizational issues and greater transparency of the processes.

Model‐based systems engineering and safety assessment: A workflow for mechatronic systems design

AbstractMechatronic systems become ever more complex because of their increasing number of interconnected safety critical components and sophistication. MBSE (Model‐based Systems Engineering) and MBSA (Model‐Based Safety Assessment) are the most commonly adopted approaches to deal with the design and safety analysis of mechatronic systems. Unfortunately, both approaches are normally adopted separately, especially in the earlier phases of system design, thus leading to a lack of communication between system engineers and the safety team. This work aims to fill that gap at a high level, that is, through process interaction. This paper proposes an enhanced V‐model for the design of safety‐critical mechatronic systems. It relates a system development process with specific safety assessment methods. Specifically, the proposed workflow details exchange flows between the RFLP (Requirements, Functional, Logical, Physical) method, the FHA (Functional Hazard Analysis), the FMEA (Failure Mode and Effects Analysis), the MBSA and simulation, and the FTA (Fault Tree Analysis). These analyses are complemented with multiphysics modeling and simulation to observe system behavior in functional and failure scenarios, with the aim of requirements verification. The design workflow has been applied to a winged Unmanned Aerial Vehicle to apply the parallel process and the necessary interaction of MBSE and MBSA approaches. The information flows between the individual activities proved effective for designing a safe system before the verification phase. The main benefit of the proposed workflow is providing both the design and safety team with some interaction points, thus avoiding a lack of safety‐critical analysis in the early phases of system design.

The impacts of contact explosions on ultra-high performance reinforced concrete slabs: experimental study and dimensional analysis

Ultra-high performance concrete (UHPC) is becoming a prevailing construction material in protective engineering. However, an insufficient research basis causes difficulty in the anti-explosion structural design of UHPC. To investigate the blast resistance of the UHPC slab (UHPCS), contact explosion tests were carried out. UHPCS exhibited superior blast resistance and a lower threshold range of failure modes than the normal reinforced concrete slab (NRCS). Compared with the NRCS, the UHPCS reached a lower damage level under the same scaled distance and had smaller craters and spalls, fewer cracks, and an absence of cross-shaped cracks. For NRCS, failure modes of medium spall, severe spall, and perforation were reached under charges of 1.0, 1.6, and 2.2 kg. In contrast, UHPCS reached medium spall, severe spall, and perforation under charges of 1.6, 3.3, and 5.0 kg. The scaled slab thicknesses (T/W1/3) of the medium spall, severe spall, and perforation of the NRCSs were 1.17, 1.27, and 1.32 times larger than those of the UHPCSs, respectively. The formulae for predicting the spall and perforation thresholds of the UHPCSs were proposed. The reduction factors were used to evaluate the mitigation effect of the blast damage on the UHPC compared to that on the NRC. The reduction factors of the crater diameter (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\gamma _\\Phi }_{C}$$\\end{document}) and the spall diameter (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\gamma _{\\Phi s}}$$\\end{document}) were determined to be 0.507 and 0.721, respectively. For quantitative analysis of the anti-explosion performance of UHPC, a simple estimation method for predicting the dimensions of the crater and spall of the UHPCS was proposed and verified based on the dimensional analysis method.

Biomechanical comparison of four isometric prosthetic ligament repair techniques for tarsal medial collateral ligament injury.

To compare the stability, ultimate strength, and isometry of 4 prosthetic ligament repairs for canine tarsal medial collateral ligament injury. 24 cadaveric canine distal hind limbs with induced medial tarsal instability were randomly divided into 4 groups. Simulated medial shearing injury of the collateral and medial malleolus were repaired using 1 of 4 isometric suture techniques: bone tunnels with nylon suture (TN), ultrahigh-molecular-weight polyethylene (UHMWPE) suture (TU), tibial bone anchor with nylon suture (AN), or talar bone anchor with UHMWPE suture (AU). Each repair was evaluated for medial stability before and after cyclic range of motion. 3 of 4 repair configurations allowed string potentiometer isometry data collection during cyclic range of motion. Each construct was subsequently tested to failure; the strength and failure mode were recorded. All repair groups showed statistically increased laxity compared to intact ligament. There was no difference in joint laxity between repair techniques. Cyclic range-of-motion testing did not increase joint laxity at any tested joint angle. Strength to failure was no different between repair groups. Isometry was achieved in the TU and TN groups. All 4 techniques improved medial stability compared to that medial collateral ligament injury; however, no technique returned stability to the tarsal of the intact ligament. All 4 techniques maintained stability after range-of-motion testing. Isometric placement of the prosthetic suture was achievable. The constructs did not provide sufficient resistance to physiologic valgus stress. Isometric placement of a prosthetic ligament is possible; secondary stabilization appears necessary to support the repair postoperatively.

Unveiling the prediction model and mechanism of the collapse of bank slope in the lancangjiang area

This study takes the bank collapse at the left bank of Badi Township of the Lidi Hydropower Station in the Lancang Area as an example. To address the lack of in-depth research on the prediction model and mechanisms of bank collapse, this study conducts field drilling surveys, investigates influencing factors, analyzes causal mechanisms, and proposes prediction methods based on the geological survey data of bank collapse in the reservoir area. The study explores the stratigraphic lithology, determines the key parameters for bank collapse prediction, and studies the failure modes and bank collapse mechanisms. It also proposes the finite element method of bank collapse to predict the width and elevation of bank collapse and provides the influence on the surrounding environment. The results show that the collapsed bank on the left bank of Badi Township is a high and steep soil-like slope, and forms the collapse and retreat type of failure mode after impoundment. The Kachukin method, the bank slope structure method, and the proposed finite element method are used to predict the width and elevation of the collapsed bank. The results indicate that the Kachujin method predicts a larger range of bank collapses and is biased towards safety. In contrast, the prediction ranges of the bank slope structure method and the finite element method are close. The bank collapse position is located in the middle and rear of the residential houses in Badi Township, which is consistent with the on-site investigation and has strong reliability. The predicted width of the bank collapse is about 34 m and the elevation is about 1,845 m. The research results can be directly applied to preventing and controlling bank collapse and have powerful practical application value.

The Effects of Strata Orientation and Water Presence on the Stability of Engineered Slopes Using DIPS and FLACSlope: A Case Study of Tubatse and Fetakgomo Engineered Road Slopes

This paper combines empirical observations, kinematic analysis, and numerical simulation to investigate slope failure susceptibility, with practical implications for regional infrastructure projects. Six slopes along the R37 road were analyzed to assess the impact of strata orientation and water presence on slope stability. The results indicate that various factors interact to destabilize the mechanical integrity of both rock and soil materials. Dry slopes were found to be less vulnerable to failure, although geological conditions remained influential. Numerical modeling using FLACSlope (version 8.1) revealed that the factor of safety (FoS) decreases as the water presence increases, highlighting the critical need for effective drainage solutions. Kinematic analysis, incorporating DIPS modeling and toppling charts, identified toppling as the most likely failure mode, with a 90% susceptibility rate, followed by planar and wedge failures at 6% and less than 5%, respectively. These findings are validated by the observed slope conditions and empirical data. Planar failures were often remnants of both sliding and toppling failures. Given the significant risk posed to road infrastructure, particularly where FoS hovers just above the stability threshold, this study emphasizes the importance of proactive, long-term slope monitoring and early mitigation strategies to prevent catastrophic failures. The results can guide infrastructure design and maintenance, ensuring safer and more resilient roadways in regions prone to slope instability. Nonetheless, the use of sophisticated slope stability modeling techniques is recommended for a thorough understanding of the mechanical dynamics of the slope material, and for catering to the shortfalls of the techniques applied in this paper.

Post fire flexural behavior of mild steel based cold-formed built-up beams exposed to elevated temperature

The use of back-to-back built-up channel beams in cold-formed steel (CFS) structures is steadily rising. The growing demand for CFS sections as a cost-effective design solution has driven the development of these CFS built-up sections. Despite this, there has been limited research on the performance of mild steel (MS) based CFS at high temperatures, particularly regarding its flexural behavior. This study thoroughly explores the behavior of MS-based CFS beams with different spans under high temperatures, followed by cooling with air or water. It assesses the impact of thermal loading and evaluates the effectiveness of these cooling methods. Experimental findings are validated and analyzed in conjunction with Finite Element Modeling (FEM) using ABAQUS and the Direct Strength Method (DSM). The study also conducts a parametric analysis to determine how the varying span that affects flexural capacity of beam. Among beams heated to the same temperature, those cooled with water exhibit slightly lower load capacities than those cooled with air. The maximum load observed is 91.21 kN for the reference specimen, while the minimum load is 39.82 kN for the specimen heated for 90 min and cooled with water, resulting in a 78.45% difference between these values. Additionally, as heating duration increases, ductility of beam also increases. Various failure modes are observed based on different heating and cooling conditions across different beam spans. This study offers valuable insights into the performance of MS-based CFS beams under thermal stress and different cooling conditions, providing important data for structural design and safety in construction.

Performance of Seismically-Compatible Fin Plate Joints under Fire Conditions

AbstractThis paper compares the performance of fin plate joints designed with and without seismic considerations under gravity loading and fire conditions. The non-seismic design, following British detailing provisions, has a thicker fin plate located higher on the beam web and it positions the beam web closer to the column face compared to the seismic design detail based on New Zealand provisions. Finite elements in ABAQUS are used to model the subassembly, which is subjected to the ISO 834 fire with and without a cooling phase. The analyses indicate the same failure mode in both subassemblies, with yielding at the beam web top bolt hole in bearing and fracture of the top bolt in shear. However, under the same fire regime, peak compressive and moment demands of the seismic detail were approximately 25% less than those for the non-seismic detail. When subjected to heating only, time to runaway failure was similar for the seismic and non-seismic detail, occurring at 15.0 and 14.8 min into the analyses respectively. When a cooling phase was included, beginning 10 min after initial fire exposure, both subassemblies recovered without failure. A parametric study showed a larger gap between the beam end and column face decreased compression in the beam but did not significantly affect the failure characteristics of the joint. Use of thicker fin plates was also found to increase the time to failure. The results show that the seismic detailing provides limited improvement over the non-seismic detail for the analysed fin plates.

Sub‐assemblage testing and fragility analysis of connections of continuous‐plasterboard suspended ceiling systems

AbstractPast earthquake reconnaissance reports highlighted extensive seismic damages to suspended ceiling components and connections, including instances of complete ceiling failures. The seismic qualification of these nonstructural elements typically requires comprehensive evaluation through full‐scale shake table testing. However, such experimental evaluation is ordinarily not possible for every change made in various components and connections of ceiling systems due to the cost and effort involved. A feasible alternative is to obtain the behavior of components and connections from sub‐assemblage testing and incorporate them in appropriate numerical ceiling models to derive mechanical responses for developing alternative or new installation schemes. This paper considers critical connections of three continuous‐plasterboard suspended ceiling systems that were evaluated using shake table‐generated motions. The connections were classified according to their attachment to typical floors and walls of building structures, and sub‐assemblage testing was conducted using both monotonic and cyclic displacement loading. The observed failure modes in each connection were detailed, and appropriate damage states were assigned as the basis for constructing connection fragility curves. The results of the sub‐assemblage testing were presented in terms of the hysteresis responses, envelope curves, nonlinear backbone curves, and cumulative energy dissipation curves. Additionally, multilinear models of the connections were derived by approximating nonlinear backbone curves’ initial‐ and post‐yield behaviors. These multilinear models were further idealized to derive three equivalent linearized models for simplified yet reasonably accurate results for linear structural analyses. Finally, fragility curves were derived for all connections, considering their cyclic displacement failure capacities.