Collapse Mitigation Research Articles

A novel 8-connected Pixel Identity GAN with Neutrosophic (ECP-IGANN) for missing imputation

Missing pixel imputation presents a critical challenge in image processing and computer vision, particularly in applications such as image restoration and inpainting. The primary objective of this paper is to accurately estimate and reconstruct missing pixel values to restore complete visual information. This paper introduces a novel model called the Enhanced Connected Pixel Identity GAN with Neutrosophic (ECP-IGANN), which is designed to address two fundamental issues inherent in existing GAN architectures for missing pixel generation: (1) mode collapse, which leads to a lack of diversity in generated pixels, and (2) the preservation of pixel integrity within the reconstructed images. ECP-IGANN incorporates two key innovations to improve missing pixel imputation. First, an identity block is integrated into the generation process to facilitate the retention of existing pixel values and ensure consistency. Second, the model calculates the values of the 8-connected neighbouring pixels around each missing pixel, thereby enhancing the coherence and integrity of the imputed pixels. The efficacy of ECP-IGANN was rigorously evaluated through extensive experimentation across five diverse datasets: BigGAN-ImageNet, the 2024 Medical Imaging Challenge Dataset, the Autonomous Vehicles Dataset, the 2024 Satellite Imagery Dataset, and the Fashion and Apparel Dataset 2024. These experiments assessed the model’s performance in terms of diversity, pixel imputation accuracy, and mode collapse mitigation, with results demonstrating significant improvements in the Inception Score (IS) and Fréchet Inception Distance (FID). ECP-IGANN markedly enhanced image segmentation performance in the validation phase across all datasets. Key metrics, such as Dice Score, Accuracy, Precision, and Recall, were improved substantially for various segmentation models, including Spatial Attention U-Net, Dense U-Net, and Residual Attention U-Net. For example, in the 2024 Medical Imaging Challenge Dataset, the Residual Attention U-Net’s Dice Score increased from 0.84 to 0.90, while accuracy improved from 0.88 to 0.93 following the application of ECP-IGANN. Similar performance enhancements were observed with the other datasets, highlighting the model’s robust generalizability across diverse imaging domains.

Mitigation of urban road collapses based on machine learning via integrating susceptibility assessment and geophysical detection validation

Road collapse is a frequent and damaging disaster in cities. The complexity and uncertainty inherent in urban environments pose significant challenges to mitigating road collapses. This paper presents a novel framework integrating machine learning-based susceptibility assessment and geophysical detection validation for urban road collapse risk reduction. Three oversampling techniques, random oversampling, synthetic minority oversampling technique for nominal and continuous features (SMOTENC), and adaptive synthetic sampling (ADASYN), are first utilized to implement data augmentation on urban road collapse accident samples. Subsequently, three machine learning models, support vector machine (SVM), random forest (RF), and extreme gradient boosting (XGBoost), are developed to evaluate road collapse susceptibility by extracting collapse-inducing patterns from historical accident data. Particularly, on-site geophysical hazard detection is conducted to validate the assessment results. The results demonstrate that XGBoost with SMOTENC achieves satisfactory performance in identifying road collapses with accuracy (0.9608) and AUC (0.9796). The spatial distribution of road collapse susceptibility in Shanghai central area follows a high-moderate-low pattern from northwest to southeast. The geophysical detection reveals a correlation between higher road collapse susceptibility and increased severity of underground diseases, validating the generalization capacity of XGBoost in actual operational environments. Additionally, the structural problems of underground pipelines are identified as the most influential factors for urban road collapse. This research offers valuable insights for urban road collapse mitigation and resilience improvement of transportation infrastructure.

Reflection characteristics of typical road defects in 3D GPR images for collapse mitigation

Road collapses pose dangerous threats to traffic safety in urban cities. Typically, these collapses result from under-road defects such as cavities, loose soil, and voids. With the development of multi-channel 3D ground penetrating radar (GPR) systems, GPR has become a routine method for inspecting the subsurface conditions of roads. However, the reflection characteristics of hidden defects in 3D GPR results have not been well studied due to the complexity of urban road structures. Consequently, accurately detecting all subsurface defects in GPR survey areas remains challenging. In this paper, numerical models of road structures with typical types of hidden defects are constructed, and their reflection characteristics in GPR B-scan profiles and C-scan depth slices are analyzed. Then, the field results obtained using a car-mounted 3D GPR system are presented to confirm the reflection characteristics of these hidden defects. Finally, the reflections of manhole covers and underground pipelines, which are the most prevalent forms of clutter in GPR images in urban environments, are compared with those of hidden defects. The findings of this paper will facilitate the accurate interpretation of field 3D GPR data for road inspections and the mitigation of road collapse accidents.

Numerical study on upgrading beam-column connections in steel framed buildings for progressive collapse mitigation

This research used intensive numerical analysis to identify weak points and structural issues important to limiting the spread of collapse. As a consequence, four specimens of strengthened and unstrengthened steel beam-column joint assemblies were examined using scaled models. The data were used to validate numerical models. The control specimen was a simple shear joint from one of the four experimental assemblies. The second specimen was a bolted steel beam column joint used as a reference specimen to represent the ideal beam-column joint often used in intermediate moment-resisting frames in seismic zones across the globe. The third specimen, like the control, but it had two side plates welded together to strengthen the joint site, while the fourth specimen had high-strength, hot-rolled steel bars pretensioned inside the joint zone. ABAQUS software was used to create numerical finite element models to evaluate the behavior of steel frame assemblies before and after upgrading. The FEM matrix included 22 specimens with various characteristics, including plate thickness, steel grade, a contact between beam flange-strengthening plates, and a column that was either welded or not welded in the first scheme, number and diameter of hot-rolled steel bars were for the second scheme. The effectiveness of the strengthening techniques was established by comparing the mode of failure and load–displacement characteristics of the investigated specimens.

Numerical Investigation on Progressive Collapse Mitigation of Steel Beam-Column Joint Using Steel Plates.

This research employed extensive numerical analyses to locate the weak areas and determine the structural issues critical to preventing the spread of collapse. As a result, three specimens were tested using scaled models of strengthened and unstrengthened steel beam-column joint assemblies. The data were utilized to verify numerical models. One simple shear joint from the three experimental assemblies was used as the control specimen (unstrengthened joint). The second was a bolted steel beam-column joint utilized as a reference specimen to reflect the ideal beam-column joint generally employed in intermediate moment-resisting frames in seismic zones worldwide. Similar to the control, the third specimen (strengthened joint) had two side plates welded together to strengthen the connection site. Numerical finite element models were developed using ABAQUS (2020) software to extensively investigate the behavior of steel frame assemblies before and after upgrading. The FEM matrix comprised 17 specimens with varying parameters, including plate thickness, steel grade, a joint between the beam flange-strengthening plates, and a column that was either welded or not welded. The effectiveness of the strengthening techniques was established by comparing the mode of failure and load-displacement characteristics of the investigated specimens. The results indicate that the average increase in peak load due to a change in plate thickness for grades A36 and A572 is approximately 22% and 8%, respectively. Plates made of A572 steel increase peak load by 30%. All strengthened specimens attained catenary action, mitigating the possibility of progressive collapse.

Mitigation of cellular collapse during drying of Eucalyptus nitens wood using supercritical CO2 dewatering

Summary Removal of lumen water by dewatering using supercritical CO2 offers an alternative method to mitigate cellular collapse in susceptible hardwoods compared to conventional timber drying methods. The anatomy of Eucalyptus nitens was quantitatively measured by light microscopy, SEM and micro-CT to provide an understanding of the mechanism of collapse during drying. These measurements were then used to recalibrate a previously developed fluid-dynamics model to predict E. nitens vessel dewatering and develop a dewatering treatment strategy for collapse mitigation. The lumens of E. nitens were from fibres (58.5% cross-section) and vessels (10.0% cross-section) with mean diameters of 8 and 142 μm, respectively. Micro-CT measurements revealed that the vessels were empty after treatment with a supercritical CO2 dewatering schedule optimised for softwood. However, the fibres remained full and this led to significant collapse during subsequent oven drying. Based on this information, a two-phase dewatering schedule was developed to include removal of fibre lumen water. Results showed that 90% of collapse could be mitigated to a change in external volume of only 3.9% provided the green moisture content was lowered to 70% before oven drying. The predicted effective diffusion coefficient of CO2 in E. nitens was comparable to Pinus radiata and they showed similar anatomical tortuosity and porosity resistance in their hydrofluidic networks. Collapse mitigation using supercritical CO2 could be combined with extraction of desirable sap components, post-dewatering drying, preservative treatment, and mechanical forming. These processes may be achieved in a single supercritical plant and apply to most anatomically similar hardwoods.

SWAMI: A SWARM-INTELLIGENT OPTIMIZATION TECHNIQUE FOR VOLTAGE COLLAPSE MITIGATION

In this paper, a voltage collapse optimization system based on comparative studies of swarm-intelligent techniques is proposed for voltage collapse mitigation in power system network. The approach draws inspiration from the idea of utilizing the intelligent behavior of swarm-based artificial machine intelligence technique coined SWAMI for voltage collapse minimization or prevention through dynamic shunt compensation of overloaded power network buses. Several simulation studies have been conducted considering three very popular and successful SWAMI agents – the PSOM, BCOM and ACOM on an IEEE benchmark power network with promising results. Simulation studies showed that the PSOM SWAMI exhibited the most stable response in terms of voltage profile collapse and recovery from voltage collapse state after voltage sensitivity studies. Safe margins of loading and optimal shunt compensations are determined based on the SWAMI techniques.

Comparative fire-following-earthquake performance of code-compliant low-rise base-isolated structures

Seismic base isolation is an effective way of protecting structures against seismic loads and is very effective in terms of both collapse mitigation of structures and protection of non-structural elements under severe ground shaking. In this study, the structural demand of base-isolated three- and four-story steel moment-resisting frames is determined in case of a fire event followed by an earthquake, and compared with the results of fixed-base frames, which have similar geometry, load, and seismic hazard for a location in California. Four compartments are selected as possible locations for fire events in each building, and beams and columns in those compartments are exposed to a representative temperature increase in time, which includes a cooling phase as well. Maximum, minimum, and residual axial force, and moment demands on elements of the fire compartments, and drift demand of structural frames on the first and second floor, where the fire is assumed to occur, are determined and compared. Results are given in terms of parameters of three-parameter log-normal distribution, hence fragility curves can be constructed for each response considered in the study. Seismic isolation is effective in reducing both maximum and residual drift demand of the frames, and axial force in the beam element for each compartment considered. Fixed-base frames have 20% more maximum axial load on beams. Beam and column elements in the four-story configuration are under relatively more moments in case of a fire, while the performance of three-story frames depends on the location of the assumed fire.

Effect of Endogenous Failure Events on the Survivability of Turboelectric Distributed Propulsion System

Recent advancements in aircraft electrification have led to the introduction of turboelectric distributed propulsion (TeDP). For instance, NASA's N3X airplane aims to curb jet fuel emissions with the aid of TeDP. However, it is crucial to analyze the survivability of the TeDP system during extreme conditions. The endogenous failure events are of specific interest as they were found to cause a significant number of accidents for commercial aircraft. While the distribution reconfiguration is necessary to meet the critical load demands under extreme failure events, it can also create a transient overload condition in the turboshaft engine. The power system survivability is further deteriorated in the presence of constant power loads. In this article, a mathematical analysis of the survivability of the system is presented to make the aircraft power system highly resilient to endogenous failure events. A power system collapse mitigation strategy is proposed by adding an energy storage system. Moreover, the analytical expressions are formulated to size the energy storage unit to prevent the system collapse. Various failure conditions are modeled using PSCAD/EMTDC to study the minimum energy storage required to prevent system collapse.

Pattern collapse mitigation by controlling atmosphere during development process for semiconductor lithography

The negative pressure atmosphere during the development process was investigated to mitigate the photoresist pattern collapse which is one of the traditional issues in the lithography processes for every generation of photoresists; i-line, KrF, ArF, ArF immersion, and recently extreme ultraviolet. The pattern collapse is caused by the capillary force between resist patterns during rinsing and drying in the development process. The main factors of capillary force are the surface tension and the contact angle of rinsing liquid and also the pattern structure (line width, space width, and height). On the other hand, the capillary force is influenced by the atmosphere pressure. In this paper, we controlled the chamber pressure during the rinsing and drying processes for the pattern collapse mitigation. The minimum critical dimension without pattern collapse under the negative pressure was found to be smaller (approximately 10% improvement) than that obtained with atmosphere pressure.

Building structural health monitoring: a tool for building collapse mitigation

Building collapse occurs recurrently worldwide on account of a myriad of variables associated with man or nature whose consequences are loss of life and properties that are sometimes incalculable. This paper aims to appraise the current advances in the topic area to identify and provide a holistic document on building structural health monitoring approaches that are fragmented in the literature to enable practitioners, stakeholders, and inspectors gain insight into the modern and cost-effective methods of building structural health monitoring to alleviate the incessant problem. It appeared that most of the approaches are interwoven and dependent on one another to obtain reliable information on building structural integrity. Apart from the traditional methods of visual inspection and non-destructive assessment of building health monitoring, it appeared the predominant and recent approaches to building health monitoring are analytics or statistics-based, statistics-sensor based, fiber optic framework, fiber optic-sensor network, and sensor-based. Arguments in the literature suggest that the analytics or statistics approach may not provide accurate information on account of the outlier and data corruption. The fiber optic approach is expensive and time consuming compared with the fiber-sensor network method. Finally, the sensor-based building health monitoring is less expensive over other approaches and provides reliable and accurate information on building integrity. Hence, we suggest future research direction should focus on the development and integration of fiber optic-sensor network and sensor-based methods of building health monitoring to improve the accuracy of the methods.

Static and dynamic tests on steel joints equipped with novel structural details for progressive collapse mitigation

This paper presents static and dynamic tests on nominally-pinned steel joints equipped with novel structural details for progressive collapse mitigation. The proposed structural details utilise the exceptional ductility and strength of stainless steel pins to enhance both the tie force and the rotational capacity of a vulnerable steel joint. The stainless steel pins along with additional supporting elements are installed in the joint region without interfering with the design for gravity loads, and they can be used for both new designs and to retrofit existing steel buildings. A static test on a vulnerable industry-standard steel fin-plate connection is first presented followed by two static tests on the same connection retrofitted with the proposed structural details. The retrofitted connections were subsequently tested under dynamic conditions with increasing imposed loading using a test setup that simulates a sudden column loss scenario. The test results showed that nominally-pinned joints equipped with the proposed structural details can achieve the required tie force capacity while undergoing rotations larger than 0.2 rad. Analytical equations based on simple joint equilibrium are used to validate the results of the static tests. An analytical method based on the energy conservation principle is also proposed and comparison with the dynamic tests shows very good predictive capability when the assumed loss of energy is 22%.

Seismic progressive collapse mitigation of buildingsusing cylindrical friction damper

The occurrence of progressive collapse induced by the removal of the vertical load-bearing element in the structure, because of fire or earthquake, has been a significant challenge between structural engineers. Progressive collapse is defined as the complete failure or failure of a part of the structure, initiating with a local rupture in a part of the building and can threaten the stability of the structure. In the current study, the behavior of the structures equipped with a cylindrical friction damper, when the vertical load-bearing elements are eliminated, is considered in two cases: 1-The load-bearing element is removed under the gravity load, and 2-The load-bearing element is removed due to the earthquake lateral forces. In order to obtain a generalized result in the seismic case, 22 pair motions presented in FEMA p 695 are applied to the structures. The study has been conducted using the vertical push down analysis for the case (1), and the nonlinear time-history analysis for the second case using OpenSEES software for 5,10, and 15-story steel frames. Results indicate that, in the first case, the load coefficient, and accordingly the strength of the structure equipped with cylindrical friction dampers are increased considerably. Furthermore, the results from the second case demonstrate that the displacements, and consequently the forces imposed to the structure in the buildings equipped with the cylindrical friction damper substantially was reduced. An optimum slip load is defined in the friction dampers, which permits the damper to start its frictional damping from this threshold load. Therefore, the optimum slip load of the damper is calculated and discussed for both cases.

Disproportionate Collapse Mitigation in Tall Mass Timber Buildings

Tall buildings are a unique type of structure with their own characteristic behaviour. They are most often occupied by a large number of people; therefore, their damage, loss of functionality, or, in worst case scenario, collapse will lead to catastrophic consequences. There are methodologies intended to provide structural integrity or increase structural robustness in tall buildings, thereby making structures resistant to disproportionate collapse, which is characterized by a cascading progression of damage that is not proportionate to the initial failure. Tall buildings are commonly constructed with steel and concrete. As a result, most of the attempts at providing structural integrity are dedicated to mitigating the effect of disproportionate collapse in the steel and concrete members, connections, and their systems. On the other hand, with rising demand for new sustainable buildings in urban areas, tall mass timber buildings have attracted increased attention nationally and internationally. Ease of modularization and offsite construction is one of the greatest advantages of using mass timber in tall building construction in the congested urban areas of major cities. A major challenge facing the engineering community is the lack of research studies regarding the structural robustness required to mitigate the potential of disproportionate collapse. The current study seeks to begin the process of understanding the behaviour of mass timber components and assemblages, and make recommendations regarding their performance and possible means to mitigate the occurrence of disproportionate collapse. These recommendations would lead to safer structural performance in the event of localized damage that has the potential to spread to a disproportionately large part of the structure.

Strengthening of precast RC beam-column connections for progressive collapse mitigation using bolted steel plates

Being one of the most critical scenarios in extreme events such as blast attacks, the progressive collapse of reinforced concrete (RC) structures has attracted the attention of structural engineering community. As precast concrete buildings are deficient in structural continuity, they are more vulnerable to progressive collapse than cast-in-situ RC buildings. Hence, effective rehabilitation techniques to upgrade beam-column joints in existing precast RC buildings for progressive collapse mitigation are needed. The goal of this study is to investigate the effectiveness of using bolted steel plates on the behavior of precast beam-column connections under sudden column-loss scenario. This study presents experiments involving one half-scale precast RC beam-column assembly, which represented the most prevalent types of existing precast beam-column joints in Saudi Arabia. One monolithic test specimen having continuity of top and bottom beam rebars was used for the sake of comparison. Another precast specimen similar to the control one was strengthened using bolted steel plates within the connection region. The progressive collapse scenario was simulated by removing the central column support and applying a sudden vertical load on this column at a rate of 100 mm/s until failure. The collapse load of both monolithic and strengthened specimens was predicted using a simplified section analysis procedure. The analysis was then used for some useful parametric studies in which the effect of different steel plate parameters on the response of test frames under middle column-loss scenario was investigated.

Scheme for beam progressive collapse mitigation

Latest recommendations have made provisions to improve structure resistance to progressive collapse in the event of interior support collapse. This paper defines a mitigating scheme to repel progressive collapse in reinforced concrete beams due to damaged interior supporting member by providing a new path to transfer the loads to other supporting members. The mitigating scheme suggests the use of unbounded unstressed externally installed fibre reinforced plastic cables with straight profile and three deviators. An open source finite element package for structural analysis (ZEUS-NL) using the fibre element approach is adopted to numerically model the mitigated beam. The proposed numerical model evaluates the progressive collapse of such beams using a push-down analysis to simulate column removal. It assumes that the anchorage and deviator locations of the external cables act as rigid arms that connect the external cables to the beam. The numerical results demonstrate that the defined mitigating scheme increases the beam resistance to progressive collapse due to interior column failure.

Scheme for beam progressive collapse mitigation

Latest recommendations have made provisions to improve structure resistance to progressive collapse in the event of interior support collapse. This paper defines a mitigating scheme to repel progressive collapse in reinforced concrete beams due to damaged interior supporting member by providing a new path to transfer the loads to other supporting members. The mitigating scheme suggests the use of unbounded unstressed externally installed fibre reinforced plastic cables with straight profile and three deviators. An open source finite element package for structural analysis (ZEUS-NL) using the fibre element approach is adopted to numerically model the mitigated beam. The proposed numerical model evaluates the progressive collapse of such beams using a push-down analysis to simulate column removal. It assumes that the anchorage and deviator locations of the external cables act as rigid arms that connect the external cables to the beam. The numerical results demonstrate that the defined mitigating scheme increases the beam resistance to progressive collapse due to interior column failure.

Technique of Optimal Placement of SVC for Voltage Collapse Mitigation

Every transmission system has voltage stability limit which may lead to voltage collapse if an undetected bulk transmission network is operated close to its operating limit. This research work uses continuation power flow method to identify voltage collapse point for Bangladesh Power System Network (BPSN). For the identification of weak buses, an analytical based technique of tangent factor has been presented. The risk of voltage collapse has been mitigated by placing SVCs at the weak buses of the system using load flow analysis. Moreover, sensitivity based approach has been introduced to determine optimal location of Static VAR Compensator (SVC) for the voltage security enhancement. A comparative analysis has been documented considering the size of reactive power to improve the loading factor of the overall network at the end of this work.

Pattern collapse mitigation in inorganic resists via a polymer freeze technique

As the lithography feature sizes continue to shrink, the aspect ratios of the patterned resist structures tend to increase as the thickness of the resist cannot be scaled down at the same pace with the resolution. This trend has resulted in the performance of leading photoresists often being limited by pattern collapse rather than their resolution. Even though several pattern collapse mitigation strategies have been successfully introduced, their performance is not sufficient to completely mitigate the issue. Here, we present a pattern collapse mitigation technique for inorganic resists, where the root cause of pattern collapse, the capillary forces present during the drying of the wafers, is circumvented by encapsulating the resist in a polymer film instead of drying it and removal of the polymer in a subsequent dry etch process. We demonstrate how the technique increases the aspect ratio of freestanding resist structures, expanding the process window towards smaller doses for resist patterned both via extreme ultraviolet interference lithography and electron beam lithography.

MACRO-ELEMENT MODEL OF A STEEL MOMENT FRAME SUBJECTED TO FIRE-INDUCED COLUMN LOSS

A progressive collapse mitigation strategy is to ensure load redistribution when a column fails due to fire. The study seeks to understand whether welded unreinforced flange-bolted web (WUF-B) moment connections can effectively redistribute loads in a structural system subjected to fire when a critical column is lost. A component (or macro-element) model was derived to simulate the WUF-B connection and validated against experimental tests and high-resolution finite element (FE) models of subassemblies at room temperature and at elevated temperature. The component model was then utilized in a 2D macro FE model of a ten-story steel-framed building subjected to the loss of a column during long fire exposure. This paper presents the collapse mechanisms and quantifies structural performance based on acceptance criteria. A parametric study on location of column loss and fire occurrence is also included.