Collapse Mechanism Research Articles

Adhesion-induced roof collapse of a rectangular micro-groove under applied pressure

ABSTRACT In soft lithography roof collapse is frequently observed on the stamp surface consisting of rectangular micro-grooves which yields unwanted contact between the sagged surface and the substrate. Deep understanding of the adhesive contact behavior is a key to design of high-performance collapse-resistant stamp. Both theoretical and numerical studies are presented for a single rectangular micro-groove in the middle of the stamp surface under applied pressure. The JKR-type adhesion solution is established by the principle of superposition and equivalent energy release rate, with a series of closed-form expressions derived which are consistent with previous studies. Finite element analysis (FEA) is performed based on virtual crack closure technique (VCCT) to investigate the roof collapse mechanism with interfacial adhesion and applied pressure considered. Comparison of theoretical, numerical, and experimental results demonstrates that both size effect and constitutive nonlinearity of the stamp on the self-collapse contact width are not obvious for shallow grooves but become prominent for deep grooves, so that the obtained analytical solution is limited to shallow grooves due to its assumptions of half-plane and linear elasticity adopted for the stamp. For deep grooves, the present FEA method shows potential to capture more accurate results.

Comparative study on collapse behavior of modular steel buildings: Experiment and analysis

With the increasing adoption of modular construction technology, understanding the modular steel buildings' collapse mechanisms has become crucial. This study presents comparative collapse tests on two modular steel substructures: specimen in corner column loss (S-CCL) and specimen in side column loss (S-SCL). The failure modes, load-bearing capacities, lateral displacements of modules, relative slips of double-layer beams, and deformation mechanisms of the components were compared. The findings reveal significant buckling at the ends of module beams far from the column loss area in both specimens, with minor buckling near the column loss area. No bolt hole fracture is observed in S-CCL, while S-SCL exhibits clear fractures. S-SCL demonstrates approximately double the load-bearing capacity of S-CCL during the elastic stage, and this increases further in the elastoplastic stage due to catenary action, ultimately reaching three times that of S-CCL. Significant lateral displacement occurs only in the double-span beam direction of S-SCL, towards the column loss area, while in other directions, displacement is minor and directed away. Digital image correlation (DIC) measurements indicate that relative slip in double-layer beams is significantly smaller in S-SCL compared to S-CCL. Strain gauge readings show that both module columns remain within the elastic range, but columns in S-SCL continue to deform in the plastic stage due to tensile forces in the connected beams, with beam ends away from the column loss area experiencing negative bending moments.

Automatic detection of local collapse mechanisms in historical masonry buildings: Fast and robust FE upper bound limit analysis

Automatic detection of local collapse mechanisms in historical masonry buildings: Fast and robust FE upper bound limit analysis

Bubble Dynamics in Sustainable Technologies: A Review of Growth, Collapse, and Heat Transfer

The study of bubble growth and collapse is of great significance in the context of sustainability due to its influence on numerous energy-related processes and technologies. Understanding the dynamics of bubble behavior is vital for optimising heat transfer efficiency, which has an energetic role in improving the performance of sustainable systems such as nuclear reactors, thermal inkjet printing, and nucleate boiling. Indeed, researchers can progress strategies to enhance the efficiency of these technologies by analysing the parameters influencing bubble growth and collapse, which can lead to reduced energy consumption and environmental impact. Although several theoretical models and experimental investigations have been achieved in the past to inspect bubble growth and collapse, a thorough review and critical assessment of the studies conducted have not yet been achieved. This review aims to provide a comprehensive understanding of the relationship between bubble dynamics and sustainability, highlighting the potential for further research and development in this area. Specifically, the scope and limitations of past research on bubble growth and collapse is conducted to fill this gap in the open literature. The review covers both numerical and experimental studies of bubble growth and collapse in a wide set of innovative industrial applications including nuclear reactors, thermal inkjet printing, nucleate boiling, hydrodynamic erosion, and ultrasonic and medicinal therapy. The current review also attempts to illustrate and evaluate the numerical methods used and underlines the most relevant results from the studies that were looked at in order to provide researchers with a clear picture of the growth and collapse of bubbles in different applications. The results give a precise understanding of the dynamics of bubble growth and collapse and the related temperature change and cumulative heat transmission from the thermal boundary layer. Additionally, it has been demonstrated that simulation-based models can effectively predict transport coefficients. However, the review observes a number of limitations of the past research on bubble growth and collapse. Due to numerical instability, very little work with respect to dynamic modelling has been carried out on the mechanisms of bubble collapse. Accordingly, a number of recommendations are made for the improvement of heat transmission during bubble growth and collapse. Specifically, future criteria for the highest heat transmission will demand more precise experimental and numerical approaches.

Collapse of an RC Building Under Construction with a Flat Slab System: Reasons, Calculations, and FE Simulations

The using of flat slab systems is a common structural solution for residential and commercial buildings as they are a cost-effective structural solution that simplifies and speeds up the construction phase. However, the flat slab systems have complex behavior, particularly in the slab–column connection zones, because of punching shear. Therefore, to prevent brittle flat slab collapse because of punching shear, there are some conditions which must be met in regulations such as Eurocode 2, American Concrete Institute’s Code, and Türkiye Building Earthquake Code—2018. Flat slab collapses because of punching shear can be caused by deficiencies in the design phase as well as deficiencies in the construction phase. The purpose of this study is to investigate the causes of flat slab collapses due to punching shear, focusing on whether these failures arise from design or construction deficiencies. The study highlights the importance of adhering to regulations to prevent brittle flat slab collapses. A case study of an actual building collapse due to punching shear was conducted. Theoretical punching shear strength was calculated based on the Türkiye Building Earthquake Code—2018. A finite element model of the collapsed part of the building was created, and collapse mechanism simulations were performed. It was examined whether the punching collapse mechanism was caused by deficiencies in the design or the construction phase. The findings revealed the critical role of proper design phases and construction practices in ensuring structural integrity.

Қазбаның төңірегіндегі тау шыңтасының кернеулік-өзгерістік күйін ескере жыныстардың табанын бекіндіру

The mechanism of deformation, displacement and collapse of rocks in a structurally disturbed heterogeneous rock mass was studied to assess the state of the rock mass around mine workings. A technology for fixing near-contour soil rocks has been developed, taking into account the state of the rock mass around the working. The parameters of the operation of anchor bolting in mines for fixing rods in workings in order to ensure the safety of mining operations are determined. The conducted studies made it possible to determine the degree of influence of mining conditions of development on displacements in near-contour rocks with various types of lining in ongoing workings. The revealed regularities of deformations can be used in calculations of manifestations of rock pressure during workings under various mining operating conditions.

Disaster mechanisms of hourglass-type karst ground collapse

Disaster mechanisms of hourglass-type karst ground collapse

Reinforced concrete plates: cracking and ultimate load through Lumped Damage Mechanics

In structural analysis, it is crucial to accurately characterize the nonlinear behavior of structures. This behavior may result on strain localization phenomena, that may lead to collapse processes. Lumped Damage Mechanics (LDM), one of the more recent nonlinear theories, has shown promise for a variety of applications. It is applied to frame elements, for static and dynamic analysis, in reinforced concrete, plain concrete or steel structures, or in continuous media, with plate elements for plain concrete or bending plate elements, for reinforced concrete slabs. This paper presents the study of reinforced concrete slabs using LDM. Damage and plastic rotations are the internal variables of the problem that characterize concrete cracking and reinforcement yielding, respectively. The results numerically obtained were confronted with experimental ones. It was observed that the model is highly accurate in describing the initiation and propagation of cracks, as well as identifying the collapse mechanism, in addition to precise Load vs. Deflection results, close to the experimental values.

Seismic vulnerability of steel tubular structures based on local Buckling driving variables

Performance-Based Earthquake Engineering (PBEE) is computationally demanding, due to the multiple high-fidelity non-linear dynamic structural response analyses required to compute fragility curves. In this manuscript we propose an efficient procedure to obtain fragility curves of complex tubular structures prone to fail due to local buckling using a model based on the Lumped Damage Mechanics. A state variable characterizing local buckling is employed as engineering demand parameter in PBEE. This state variable is a scalar, derived from lumped damage mechanics and taking values between 0 and 1, which characterizes the degree of local buckling (LB). A procedure to identify and define global collapse mechanisms using the local buckling state variable at the nodes is proposed, which serves as the EDP for computing the structure's fragility curves. To evaluate the seismic vulnerability, incremental dynamic analyses are conducted. The main results demonstrate efficiency of the mechanical model in a PBEE framework, and that the internal variables indicating local buckling can be considered objective indicators of collapse for Tubular complex steel frames. Results show how to identify the global failure mechanisms that are more likely to appear for each frame.

Seismic design approach for steel K-shaped eccentrically braced frames

This paper aims to propose a design approach for K-shaped Eccentrically Braced Frames (K-EBFs) according to the Theory of Plastic Mechanism Control in α−θ plane (TPMC(θ)). The novelty is the use of a new kinematic design parameter to avoid undesired collapse mechanisms, i.e. the plastic rotation θ of the dissipative members. Despite an increase of computational burden, with TPMC(θ) it is possible to obtain shallower column sections and, therefore, cheaper design solutions rather than those obtained by means of the original approach in the α−δ plane where the design parameter was the top sway displacement δ of the structure. The TPMC is an optimal design approach to overcome limitations due to the application of the simplified design criteria suggested by the code. It is based on a solid theoretical background and proposed as a design tool of seismic-resistant structures able to failure by exhibiting a collapse mechanism of global type. The design of several structures with different height is herein proposed, and the accuracy of the design procedure is validated through both pushover ad Incremental Dynamic Analyses (IDA) performed using natural records.

The blockage and erosion characteristics of woody debris flow on an erodible gully bed: Insight from a small-scale model experiment

During the transportation process of debris flow with large wood (LW), phenomena such as channel blockage and collapse frequently occurs, resulting in increased discharge surges, heightened erosion intensity, and amplified damage. Accurately predicted the blockage performance is the basis of evaluating the damage and disaster mitigation of woody debris flow. In this study, we conducted a series of laboratory experiments of woody debris flow on erodible gully bed. The experiment results show that the final blockage types can be divided into three types: non-blockage, blockage, and semi-blockage. Temporary blockage will cause abundant sediment deposited temporarily and then released instantaneously, resulting in destructive surges and eventually lead to semi-blockage and non-blockage. The blockage degree is positively correlated with the relative length, relative content of LW, and bulk density of debris flow, but negatively correlated with slope. Channel blockage is often accompanied by significant local erosion effect, and the erosion depth of downstream channel increases with the increase in blockage degree. The blockage and collapse mechanism of woody debris flow was analyzed, and the results emphasized that channel erosion promoted the outbreak of blockage collapse. Based on the analysis of blockage performance, we propose an improved blockage criterion F to evaluate the blockage degree, and the high probability range of temporary blockage is determined as 1.5–5.0. The results can provide reference for the risk assessment and mitigation of woody debris flow.

Instability and collapse mechanisms of O2 and N2 nanobubble gas–liquid interfaces: A molecular dynamics simulation study

Nanobubbles, with their stability and oxidative properties, are widely applied in biomedicine, flotation, and environmental remediation. While experimental studies have explored their application effects, the dynamic behavioral characteristics of gas-containing nanobubbles during collapse remain insufficiently investigated. This study employs molecular dynamics simulation to examine nanobubble collapse under various conditions, including impact velocities, gas types, bubble sizes, and gas densities. Results show that increasing bubble size expands the microjet radiation area, while higher impact velocities increase microjet velocities. Gas types affect the jet radiation area due to differences in van der Waals forces and solubility. Vacuum nanobubbles exhibit higher maximum jet velocities than nitrogen and oxygen nanobubbles. Gas cushioning and compression rebound significantly influence maximum jet velocity. Microjets induce vortex structures, gas surface changes, and local pressure increases, leading to secondary water hammer impacts. Simulation results align well with theoretical calculations. This study provides the theoretical foundation for the industrial-scale implementation of nanobubble cavitation technology.

Numerical investigation on bending characteristic and ductile fracture of AA7075 thin-walled beam using advanced orthotropic plasticity and fracture models

Thin-walled structures manufactured from the 7075 aluminum alloy are gaining tremendous attention in the automotive industry for their potential to reduce vehicle weight. However, the bending characteristics and rupture behavior of the AA7075 thin-walled beams under unexpected collision events have not been extensively studied. This study aims to fill that gap through a detailed numerical investigation of the bending deformation and failure mechanism of AA7075 thin-walled beams under quasi-static three-point bending at room temperature. Full-size, three-dimensional numerical simulations of laboratory-scale AA7075-T6 hat-shaped beam were conducted using the ABAQUS/Explicit solver. The material elastic–plastic response is described by a rate-independent constitutive description, incorporating advanced non-quadratic orthotropic plasticity and anisotropic ductile fracture criteria via VUMAT subroutines. Results indicate that the simulations accurately reproduced experimental observations, including the loading-displacement curves and deformation patterns. The bending behavior of the AA7075-T6 thin-walled beams aligns with typical bending collapse mechanisms, consistent with Kecman’s theory. The rupture process exhibits ductile fracture characteristics, with heterogeneous stress distribution across the material thickness affecting crack initiation rates between the upper and lower surfaces. Notably, the stress state at the fracture’s half-thickness section approximates an equi-biaxial tension condition. These findings provide essential insights into the bending deformation and failure mechanisms of AA7075 thin-walled structures under unexpected impact loading.

Seismic assessment of churches through integration of digital survey, texture recognition and distinct element modelling

The paper proposes an integrated methodology for the seismic assessment of masonry churches, which exploits the recent progresses of digital survey tools, image-processing algorithms for automatic texture identification, and non-linear seismic analysis. Starting with the digital survey of structural macro-elements, which provides accurate information on geometry, defects and blocks arrangement, discrete element models are generated. Then, a pushover analysis is carried out, which allows to detect local collapse mechanisms and follow their development up to failure. The capacity curve of the macro-element is therefore obtained, including both ascending and descending branches. The effect of retrofitting measures is directly considered within the model and their efficacy evaluated in terms of variation in acceleration and displacement capacity. The proposed methodology is described step-by-step through the application to the case study of the Romanesque church of Santa Maria Maggiore in Tuscania, Italy.

Operational Modal Analysis and Safety Assessment of a Historical Masonry Bell Tower

The seismic assessment of historical masonry bell towers is of significant interest, particularly in Italy, due to their widespread presence and inherent vulnerability given by their slenderness. According to technical codes and standard practice, the seismic evaluation of masonry bell towers can be conducted using a range of methodologies that vary in their level of detail. This paper presents a case study of a historical masonry bell tower located in the Caserta Province (Italy). Extensive investigative efforts were undertaken to determine the tower’s key geometric and structural characteristics, as well as to document ongoing damage phenomena. The dynamic behavior of the tower was assessed through ambient vibration testing, which enabled the identification of the principal modal shapes and corresponding frequencies, also highlighting peculiar dynamical characteristics caused by the damage conditions. Subsequently, the seismic assessment was carried out using both Level 1 (simplified mechanical) and Level 2 (kinematic limit analysis) methodologies. This assessment helped identify the most probable collapse mechanisms and laid the foundation for employing more advanced methodologies to design necessary retrofitting interventions. The study emphasizes the importance of Level 2 analyses for structures where out-of-plane failure mechanisms are likely due to pre-existing cracking. Both approaches provide less-than-unity acceleration factors, ranging from 0.45 for Level 1 (assuming non-ductile behavior) to 0.59 for Level 2, in this case specifically using the information available about existing cracking pattern.

Structural health assessment of existing dams based on non-destructive testing, physics-based models and machine learning tools

The safe operation of dams is ensured by monitoring systems that collect periodic information on environmental conditions (for example, temperature and water level) and on the structural response to external actions. In newly built or retrofitted facilities, large networks of sensors can take daily measurements that are automatically transferred to servers. In other cases, additional information can be acquired, occasionally or systematically, through emerging drone-based non-contact full-field techniques.The measurements are processed by various analytical and machine learning tools trained on historical data sets, capable of highlighting any anomalous recordings. Monitoring data can also support the accurate calibration of a physics-based model of the structure, usually built in the finite element framework. The analyses carried out by the digital twin allow the experimental database to be expanded with the displacements evaluated in the event of extreme environmental conditions, damage or collapse mechanisms never occurred before.This contribution illustrates an integrated approach to the safety assessment of existing dams that combines experimental, computational and data processing methodologies. Attention is particularly focused on model calibration procedures and on the uncertainties that influence the characteristics of the joints. The presented results of the validation studies performed by the Authors on benchmark and real-scale problems highlight the merits and limitations of alternative approaches to data exploitation and remote measurement.

An Evaluation of the Structural Behaviour of Historic Buildings Under Seismic Action: A Multidisciplinary Approach Using Two Case Studies

The evaluation of the structural behaviour of iconic historic buildings represents one of the most current structural engineering research topics. However, despite the various research works carried out during recent decades, several issues still remain open. One of the most important aspects is related to the correct reconstruction of the complex geometries that characterise this type of construction and that influence structural behaviour, especially in the presence of the horizontal loads caused by seismic action. For these reasons, different techniques have been proposed based on the use of laser scanners, Unmanned Aerial Vehicles (UAVs), and terrestrial photogrammetry. At the same time, several analysis methods have been developed that include the use of linear and non-linear approaches. In this present paper, the seismic performance of the Santa Maria Novella basilica and Santa Maria di Collemaggio basilica (before the partial collapse due to the 2009 L’Aquila earthquake) were investigated in detail by means of several numerical analyses. In particular, a series of non-linear time history analyses (NTHAs) were carried out, as reported in the Italian Building Code. To represent the non-linear behaviour of the main structural elements, smeared cracking (CSC) constitutive law was adopted. The geometry of the structures was reconstructed from a complete laser scanner survey of the churches, in order to consider all the intrinsic irregularities that characterise the heritage buildings. Finally, a comparison between the structural behaviour of the two case studies was carried out, highlighting the differences and similar aspects, focusing on possible collapse mechanisms and the identification of the most critical structural elements represented, in both cases analysed, by the main pillars of the transept.

Investigation of the Seismic Performance of a Multi-Story, Multi-Bay Special Truss Moment Steel Frame with X-Diagonal Shape Memory Alloy Bars

In this work, the seismic response of a multi-story, multi-bay special truss moment frame (STMF) with Ni-Ti shape memory alloys (SMAs) incorporated in the form of X-diagonal braces in the special segment is investigated. The diameter of the SMAs per diagonal in each floor was initially determined, considering the expected ultimate strength of the special segment, developed when the frame reaches its target drift and the desirable collapse mechanism, i.e., the formation of plastic hinges, according to the performance-based plastic design procedure. To further investigate the response of the structure with the SMAs incorporated, half the calculated SMA diameters were introduced. Continuing, three more cases were investigated: the mean value of the SMA diameter was introduced at each floor (case DC1), half the SMA diameter of case DC1 (case DC2), and twice the SMA diameter of case DC1 (case CD3). Dynamic time history analyses under seven benchmark earthquakes were conducted using commercial nonlinear Finite Element software (SeismoStruct 2024). Results were presented in the form of top-displacement time histories, the SMAs force–displacement curves, and maximum inter-story drifts, calculating also maximum SMA displacements. The analysis outcomes highlight the potential of the SMAs to be considered as a novel material in the seismic retrofit of steel structures. Both design approaches presented exhibit a certain amount of effectiveness, depending on the distribution, with the placement of the SMA bars and the seismic excitation considered. Further research is suggested to fully understand the capabilities of the use of SMAs as dissipation devices in steel structures.

Testing continuous spontaneous localization model with charged macromolecules

Abstract In the last decade, a growing interest has been devoted to models of spontaneous collapse of the wavefunction, known also as collapse models. They coherently solve the well-known quantum measurement problem by suitably modifying the Schrödinger evolution. Quantum experiments are now finally within the reach of testing such models (and thus testing the limits of quantum theory). Here, we propose a method based on a two-ions confined in a linear Paul trap to possibly enhance the testing capabilities of such experiments. The combination of an atomic and a macromolecular ion provide a good match for the cooling of the motional degrees of freedom and a non-negligible insight in the collapse mechanism, respectively.

How does a soft collision orogen uplift and collapse? Insight from the eastern Central Asian Orogenic Belt

The mechanism of uplift and collapse is critical for understanding orogenic evolution within the Wilson cycle. The Central Asian Orogenic Belt (CAOB) represents one of the largest Phanerozoic accretionary orogens on Earth, experiencing terminal soft collision following the closure of the Paleo-Asian Ocean. However, the timing and mechanism of crustal thickening and thinning in the eastern CAOB remain unclear. Here, we present geochronological, mineralogical, geochemical, and Sr-Nd-Hf isotopic data of the newly identified Late Triassic bimodal dike associations in the easternmost CAOB. The ca. 236−230 Ma mafic dikes can be divided into two groups based on petrographic and geochemical characteristics. Major element modeling using the MELTS software indicates that they evolved via independent differentiation paths. Trace element and isotope simulations reveal that the ca. 236−230 Ma mafic dikes originated from the 4%−10% partial melting of spinel- to garnet-lherzolite lithospheric mantle sources over a range of depths, with varying inputs of asthenospheric mantle materials. Coeval ca. 233 Ma felsic dikes exhibit adakitic geochemical characteristics and strong imprints of crust-mantle interaction, suggesting derivation from melting of a heated juvenile mafic lower crust as a result of the upwelling of asthenospheric mantle. The formation of bimodal dike associations records the transition from lithospheric mantle thinning to delamination. Integrating a large dataset and employing multiple geochemical proxies, our results reveal that the crust of the easternmost CAOB reached a thickness of 54 ± 3 km at ca. 280−255 Ma, likely resulting from magmatic underplating due to rollback of the subducting Paleo-Asian Oceanic slab. This region underwent a further slight increase in crustal thickness to 61 ± 2 km at ca. 254−237 Ma in response to limited tectonic shortening associated with soft collision orogeny before it thinned to 45 ± 13 km at ca. 236−210 Ma due to lithospheric delamination during post-collisional extension. Our findings reveal that the uplift of the eastern CAOB was primarily driven by magmatic underplating, with minimal contribution from tectonic shortening. Lithospheric delamination emerged as an important factor leading to the eventual collapse of the eastern CAOB. Compared to typical hard collisional orogens (e.g., the Himalaya-Tibet orogen), the CAOB experienced significantly weaker tectonic shortening followed by similar lithospheric delamination during post-collisional extension. This study highlights the importance of integrating geochemical and isotopic data in quantifying the complex evolutionary histories of ancient collisional orogenic belts.