Global Deformation Research Articles

THE ROLE OF CARDIAC MAGNETIC RESONANCE IN CLINICAL MONITORING AND ASSESSMENT OF PATHOGENETIC THERAPY EFFICIENCY IN PATIENTS WITH SEVERE COURSE OF MYOCARDITIS

Introduction. Diagnosis of myocarditis often causes significant difficulties due to the heterogeneity of clinical manifestations, the absence of specific symptoms and generally recognized recommendations for diagnosis and treatment. In recent years cardiac magnetic resonance (CMR) has become not only the most common and informative diagnostic tool for myocarditis, but also a method of monitoring the effectiveness of anti-inflammatory therapy.The purpose of the study was to investigate the structural and functional state of the heart and the prevalence of the inflammatory process in patients with severe course of myocarditis associated with COVID-19 infection, who received glucocorticoid therapy.Material and methods. 80 patients with a severe course of myocarditis and reduced ejection fraction (EF) of the left ventricle (LV) were included and divided into 4 groups: 1st group - 25 patients who received glucocorticoid (GC) therapy and had a history of COVID-19 infection; the 2nd group – 25 patients who received GC therapy and did not have a history of COVID-19 infection; the 3rd group – 15 patients who did not receive GC therapy and had a history of COVID-19 infection; the 4th group – 15 patients who did not receive GC therapy and had no history of COVID-19 infection. All patients underwent echocardiography with the speckle-tracking technique and CMR with gadolinium enhancement.Results and discussion. The use of glucocorticoids in addition to optimal drug therapy for heart failure in patients with severe myocarditis who had a recent history of COVID-19 infection showed high efficacy after 6 months: the number of LV segments with inflammatory changes or delayed enhancement on CMR was, respectively by 44,2% and 32,5% less, and the value of the LV EF and the index of longitudinal global systolic deformation of the left ventricle were 15,0% and 24,3% higher in comparison with those in patients who did not receive pathogenetic therapy. In patients of the 1st group, the absence of a linear lesion on CMR at the onset of the disease was associated with recovery of LVEF to ≥50% after 6 months of treatment (r=0,66; p<0.01); a similar regularity was established also in the 2nd group (r=0,59; p<0.05). On the other hand, in patients of the 3rd and 4th groups, who did not receive immunosuppressive therapy with GC, no reliable correlations were established between the absence of a linear lesion on CMR at the onset of myocarditis and recovery of LVEF after 6 months.Conclusions. CMR in patients with myocarditis, including those associated with coronavirus disease, is the main non-invasive method for diagnosis, clinical monitoring, prognosis and determining the tactics of pathogenetic therapy. The presence of a linear lesion on CMR in patients with myocarditis is associated both with a more severe course of the disease, pronounced dilatation and a more significant violation of the LV contractile ability at the onset of the disease, and with a slower recovery of the structural and functional state of the heart despite the influence of drug therapy.

Short-Segment Fusion vs. Isolated Decompression in Lumbar Spinal Canal Stenosis Patients with Cobb Angles Over 20 Degrees

Background ContextLumbar decompression and short-segment lumbar fusion are standard procedures for short-segment lumbar canal stenosis, even in patients with moderate Cobb angles. Adult degenerative scoliosis is diagnosed at a threshold of 10 degrees, and patients with coronal Cobb angles over 30 degrees are recommended for long fusion due to global spinal deformity. However, there is a lack of research on clinical outcomes in patients with moderate coronal deformity, such as Cobb angles between 20 and 30 degrees. PurposeThis study aims to investigate the radiographic and clinical outcome differences between isolated decompression and short-segment interbody fusion for lumbar spinal canal stenosis in patients with moderate coronal deformity. Study DesignA retrospective analysis of a prospectively collected registry Patient SamplePatients with Cobb angle exceeding 20 degrees who underwent 1- or 2- levels of lumbar surgery for lumbar canal stenosis. Patients diagnosed as spinal deformity were excluded. Outcome MeasuresPatient-reported outcomes included Oswestry Disability Index (ODI), VAS back, VAS leg, Short Form 12 Physical Component Score (SF-12 PCS) and Mental Component Score (SF-12 MCS), and Patient-Reported Outcomes Measurement Information System Physical Function (PROMIS-PF) at preoperative, 12-week postoperative, and 1-year postoperative timepoints. Preoperative and postoperative spinopelvic alignment was assessed using Cobb angle, pelvic tilt, sacral slope, pelvic incidence, lumbar lordosis and PI minus LL. MethodsA propensity score-matched analysis with the overlap weighting was utilized to investigate patient-reported outcomes at 12-week and 1-year postoperatively between the surgery groups. Spinopelvic alignments were compared between preoperative and 1-year postoperative timepoint using a linear mixed-effect model. ResultsBefore overlap weighting, the two surgery groups showed significant differences in age and diagnosis. No obvious sagittal malalignment was observed (decompression, 7.4° vs. fusion, 11.5°). After propensity score weighting, the fusion groups exhibited significantly better ODI and VAS back at the 1-year timepoint (ODI: fusion, 16.6 vs. decompression, 28.1, P=0.013; VAS back: fusion, 1.5 ± 2.1 vs. decompression, 3.7 ± 1.9, P<0.001). Radiographic assessment showed that the fusion group achieved better PI minus LL compared to decompression group (15° vs. 10°, P=0.008) ConclusionIn patients with degenerative scoliosis and a Cobb angle greater than 20 degrees, short-segment lumbar fusion surgery may result in enhanced improvement for short-segment lumbar pathology compared to isolated decompression.

Speckle tracking echocardiography as a predictor of location of ablation sites in candidates to catheter ablation for recurrent ventricular tachycardia

Abstract Background Preoperative imaging is essential before a ventricular tachycardia (VT) ablation procedure, to improve operative outcomes and reduce procedural times. Although MRI is the gold standard, it has several limitations, including patient compliance, possible presence of non-MRI-compatible devices, and long acquisition time. Speckle tracking echocardiography (STE) is a reliable and appealing technique that quantifies regional and global myocardial deformation, as well as layer-specific (endo-, mid- and epicardial) longitudinal strain, without MRI limitations. Purpose This study aimed to evaluate the efficacy of STE in predicting VT ablation sites. Methods In this study, we compared the bull’s eye segmentation of the left ventricle, global and layer-specific, obtained with STE (TomTec Arena), to investigate whether echocardiography can predict the areas of scar and late potential, as identified by electroanatomic mapping (EnSite X mapping, HD Grid mapping catheter, Abbott). Strain analysis and electroanatomic mapping data were matched segment-by-segment to obtain pairs of endocardial strain and bipolar substrate maps, as well as pairs of midmyocardial/epicardial strain and unipolar substrate maps. Results Twenty-three consecutive patients with an indication for catheter ablation for recurrent VT were enrolled. All patients were being treated with beta-blockers, 52% were taking amiodarone, and only 2 patients were on mexiletine. A total of 1170 pairs of bull’s eye segments were available for analysis. A binary logistic mixed-effects model was used to predict the presence of electroanatomical scar based on strain echocardiography data, to account for interpatient variability. The study findings highlighted a close correlation between the bipolar map and endocardial strain values, and between the unipolar map and midmyocardial strain values. Progressively higher (less negative) values of endocardial strain proved predictive of bipolar electroanatomical scar, with an increase in the odds ratio of bipolar electroanatomical scar equal to 6.2% (95% confidence interval 2.5%-10%) for each unit increase in strain values. Similarly, progressively higher values of midmyocardial strain were predictive of unipolar electroanatomical scar, with an increase in the odds ratio of unipolar electroanatomical scar equal to 6.2% (95% confidence interval 1.2%-11.4%) for each unit increase in strain values. Conclusions The data from our study showed an anatomical correspondence between the areas of low potential identified by electroanatomical mapping and the areas of anomalous longitudinal strain. In particular, the endocardial strain correlates with the bipolar map, and the meso-epicardial strain correlates with the unipolar map. These data may prove useful in the appropriate planning of the procedure in patients with an indication for catheter ablation in the context of recurrent VT.

Impact behavior of the SCS panel with hybrid energy absorbing components: Experimental and analytical studies

A new steel-concrete-steel panel with front aluminum foam layer and rear energy absorbing connector (SCS-FL-EAC) was firstly developed. The dynamic behavior of SCS-FL-EAC was studied through conducting drop-weight impact tests. Three stages of impact process of SCS-FL-EAC were identified. The aluminum foam layer and energy absorbing connector were crushed under impact loading. The aluminum foam layer reached densification, and a local indention was observed beneath the projectile. Plastic hinges were also found at the corners of the pleated steel plate of the energy absorbing connector. The SCS panel exhibited the combination of bi-linear global flexural deformation and local deformation. Furthermore, the effects of aluminum foam layer on the impact resistant performances of SCS-FL-EAC were investigated. The results indicated that the inclusion of the aluminum foam layer effectively mitigated inertial effects and reduced the maximum impact force. Additionally, the SCS-FL-EAC demonstrated improved impact-resistant performances with an increased thickness of the aluminum foam layer. Furthermore, an analytical model was proposed to predict the force and displacement responses of SCS-FL-EAC subjected to impact load, and the predicted impact responses showed good agreement with experimental results.

MSIreg: an R package for unsupervised coregistration of mass spectrometry and H&E images.

Joint analysis of mass spectrometry images (MS images) and microscopy images of hematoxylin and eosin (H&E) stained tissues assists pathologists in characterizing the morphological structure of the tissues, and in performing diagnosis. Unfortunately, the analysis is undermined by substantial differences between these modalities in terms of aspect ratios, spatial resolution, number of channels in each image, as well as by large global or small local elastic spatial deformations of one image with respect to the other. Therefore, accurate coregistration of the images is a critical pre-requisite for their joint interpretation. We introduce MSIreg, an open-source R package for coregistration of MSI and H&E images. MSIreg is designed for high-dimensional MSI experiments where each spatial location is represented by thousands of mass features. Unlike most existing coregistration methods, MSIreg implements a landmark free workflow, and quantitative metrics for performance evaluation. We evaluate the performance of MSIreg on six case studies, including coregistration of contiguous tissues with large deformations, as well as simultaneous coregistration of 29 tissue microarray cores. The R package, installation instructions, and fully reproducible vignettes describing methods and Case Studies are are available open-source under the GPL-3.0 license at https://github.com/sslakkimsetty/msireg/.

Programmable heterogeneous lamellar lattice architecture for dual mechanical protection

Shear bands frequently appear in lattice architectures subjected to compression, leading to an unstable stress-strain curve and global deformation. This deformation mechanism reduces their energy absorption and loading-bearing capacity and causes the architectures to prioritize mechanical protection of external components at the expense of the entire structure. Here, we leverage the design freedom offered by additive manufacturing and the geometrical relation of dual-phase nanolamellar crystals to fabricate heterogeneous lamellar lattice architectures consisting of body-centered cubic (BCC) and face-centered cubic (FCC) unit cells in alternating lamella. The lamellar lattice demonstrates more than 10 and 9 times higher specific energy absorption and energy absorption efficiency, respectively, compared to the BCC lattice. The drastic improvement arises as the nucleation of shear bands is inhibited by the discrete energy threshold for plastic buckling of adjacent heterogeneous lattice lamella during loading. Despite its lower density than the FCC lattice, the lamellar lattice exhibits significant enhancement in plateau stress and crushing force efficiency, attributed to the strengthening effect induced by simultaneous deformation of unit cells in the BCC lattice lamella and the resulting cushion shielding effect. The design improves the global mechanical properties, making lamellar lattices compare favorably against numerous materials proposed for mechanical protection. Additionally, it provides opportunities to program the local mechanical response, achieving programmable internal protection alongside overall external protection. This work provides a different route to design lattice architecture by combining internal and external dual mechanical protection, enabling a generation of multiple mechanical protectors in aerospace, automotive, and transportation fields.

Smart carbon fiber reinforced plastic tubes with electromechanical structural health self-monitoring system

Carbon fiber-reinforced plastics (CFRPs), are utilized in the various mobilities owing to their superior specific structural rigidity. However, the studies for the structural health monitoring (SHM) of a tubular CFRP are relatively limited compared to its market share although it is directly related to the structural duties. Thus, this study investigated structural health self-monitoring (SHSm) of tubular CFRPs by monitoring their electrical resistances simultaneously. Multiple electrodes monitored electrical resistances of the CFRP tubes in terms of their mechanical deformation realizing condition-based SHM without any sensors. The proposed self-monitoring technology enabled not only local but also global deformation even after the mechanical fractures. Furthermore, the proposed self-monitoring method was comparatively analyzed and verified with corresponding mechanics and finite element analysis. Therefore, real-time SHSm technology for tubular CFRPs with various fiber stacking configurations was realised in this study covering all the deformation types over the whole structures.

Tunable wave coupling in periodically rotated Miura-ori tubes.

Origami folding structures are vital in shaping programmable mechanical material properties. Of particular note, tunable dynamical properties of elastic wave propagation in origami structures have been reported. Despite the promising features of origami metamaterials, the influence of the kinematics of tessellated origami structures on elastic wave propagation remain unexplored. This study proposes elastic metamaterials using connected Miura-ori tubes, the kinematics of which are coupled by folding and unfolding motions in a tubular axis; achieved by periodically connecting non-rotated and rotated Miura-ori tubes. The kinematics generate wave modes with localized deformations within the unit cell of the metamaterials, affecting the global elastic deformation of Miura-ori tubes via the coupling of wave modes. Dispersion analysis, using the generalized Bloch wave framework based on bar-and-hinge models, verifies the influence of kinematics in the connected tubes on elastic wave propagation. Furthermore, folding the connected tubes changes the coupling strength of wave modes between the kinematics and global elastic deformation of the tubes by breaking the ideal kinematics. The coupling of wave modescontributes to the formation of the band gaps and their tunability. These findings enable adaptive and in situ tunability of band structures to prohibit elastic waves in the desired frequency ranges.This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'.

Innovative study of the fetal heart in monochorionic multiple births

Introduction. Fetal echocardiography is currently one of the main methods of prenatal diagnosis. However, in recent years, attention has shifted towards the use of ultrasound to assess fetal myocardial function.The aim of this study is compare global longitudinal deformation of the myocardium of the left (LV) and right ventricles (RV) of the heart in fetuses with uncomplicated singleton pregnancy, in fetuses from monochorionic twins with transfusion syndrome, selective growth retardation and in uncomplicated monochorionic multiple pregnancy.Material and methods. A prospective cohort study was conducted which included 60 pregnant patients: Group I — patients with an uncomplicated singleton pregnancy (n=25); Group II — 35 patients with monochorionic diamniotic twins, whose pregnancy in 10 cases was complicated by feto-fetal transfusion syndrome (stages I-III according to Quintero R.A.), in 10 cases — selective growth retardation of the second fetus and in 15 cases monochorionic twins without complications. The following parameters were determined: global longitudinal deformation (GLD) of the myocardium of the ventricles of fetal hearts using the speckle tracking method of ejection fraction (EF), end-diastolic and end-systolic volumes of the ventricles of the heart.Results. Significant differences were established in GLD of RV and LV between singleton and monochorionic multiple pregnancies (LV: -21.2 ± 2.03 versus -23.41 ± 0 .25, p = 0.003); RV: — 20.3 ± 2.5 versus -23.3 ± 2.5, p = 0.013). Significant differences were revealed in GLD of the LV and RV in recipient fetuses before and after laser coagulation of placental anastomoses (LPCA) [LV in recipients before LCPA (- 20.4 ± 2.98) versus LV recipient after LCPA (-24.2 ± 3.3), p = 0.018], [RV in recipients before LKPA (- 20.4 ± 2.8) vs. RV in recipients after laser coagulation of placental anastomoses (-23.7 ± 3.4, p = 0.012].Conclusion. Assessment of the cardiac function of fetuses from monochorionic twins using the echocardiographic speckle tracking technique makes it possible to identify early changes in fetal myocardial function in twins from monochorionic diamniotic twins, as well as to carry out reliable testing monitoring changes in cardiac function over time.

In‐Plane Energy Absorption Properties of Novel Curved‐Ligaments Auxetic Cellular Structures with Dual‐Platform Performance

To improve the energy absorption capacity of honeycomb, four novel curved‐ligaments auxetic cellular structures (CLACS‐i [i = 1, 2, 3, 4]) based on the Diabolo‐shaped honeycomb (DSH) are introduced in this article. In the simulation results, it is demonstrated that the energy absorption performance of CLACS‐i (i = 1, 2, 3, 4) surpasses that of DSH under low‐, medium‐, and high‐velocity impacts. However, the negative Poisson's ratio effect of novel structures is inferior to that of DSH. With the increase in impact velocity, the inertial effect of the structure is enhanced, and the deformation mode of the structure changes from global deformation to local deformation. Furthermore, different impact velocities and geometric parameters also affect the energy absorption capacity of the structures. Platform stress and specific energy absorption (SEA) of CLACS‐i (i = 1, 2, 3, 4) increase with the increase of velocity. Under medium‐velocity impact loading, the platform stress and SEA of CLACS‐i (i = 1, 2, 3, 4) increase as the geometric parameter θ decreases and the wall thickness t increases. In this study, a reference is provided for the optimal design and application of honeycomb energy‐absorbing components.

Study on contact characteristics of double-disk arc-contact lapping for cylindrical rollers based on influence coefficient method

The double-disk arc-contact lapping (DDACL) method is a novel for precision machining of the rolling surface of cylindrical roller. The contact characteristics of DDACL process can affect the lapping quality of the bearing roller. However, there is a limited amount of study on the contact theory of DDACL. Therefore, the objective of this research is to create a semi-analytical modeling approach that can effectively and accurately forecast the contact characteristics of DDACL. In the initial step, the spatial coordinate transformation was employed to establish accurate mathematical models that represents the surfaces of the cylindrical roller and arc groove. Subsequently, the potential contact area was determined and subdivided into discrete elements based on the differential geometry principles. The accurate flexibility of the potential contact area is achieved by utilizing the interpolation theory and considering both the global and local deformations of the roller and groove. By employing the influence coefficient method and the force-deformation coordination relation, the deformation and contact force can be calculated. Finally, the accuracy and efficiency of this calculation is confirmed through a comparison between the finite element method (FEM) and the proposed method.

Low velocity impact resistance of hybrid CFRP‐elastomer‐metal laminates: Influence of stacking sequence and impact conditions on damage mechanisms

AbstractFiber‐metal laminates (FMLs) are generally regarded as excellent lightweight materials for advanced structure design. To enhance the mechanical properties, the common FMLs can be optimized using carbon fibers. However, the combination of carbon fibers with aluminum induces interfacial challenges. Preventing galvanic corrosion with elastomeric interlayers is an effective solution. The lay‐up configuration greatly effects the impact damage resistance of hybrid CFRP‐elastomer‐metal laminates (HyCEMLs). In this work, micro‐CT scans and optical micrographic inspections on HyCEMLs are conducted after impact tests to ascertain the microstructural origins behind the mechanical performance changes. In addition, finite element models of different HyCEML configurations are built to complement the limited experimental data. The damage mechanisms of HyCEML with different configurations under various impact conditions are further compared. The numerical results suggest that impact energy is a more informative measure in terms of damage mode and size than impact velocity and momentum. Results also indicate that when the thickness for each sub‐laminate of HyCEML is maintained the same, hybrid laminates with aluminum stacked outside is beneficial for delaying the occurrence of matrix cracking and delaminations, and enhances HyCEML's resistance to global deformation. These findings will contribute to engineering hybrid laminates with desired impact performance for lightweight load‐bearing structures.Highlights The hybrid laminate with elastomeric interlayers is a forward‐looking solution in impact applications. Impact energy is a more informative measure in terms of assessing the damage mode and extent in HyCEMLs. The influence of stacking sequence on damage mechanisms of HyCEMLs is evaluated. Microstructural origins behind variations of hybrid laminates in the impact resistance are revealed.

Comprehensive evaluation of right ventricular function in patients with acute pulmonary embolism

Objective. To study indices of right ventricular (RV) longitudinal deformation at transthoracic echocardiography (TTE) in patients with acute pulmonary embolism (APE), to determine their threshold values; to study indices of right ventricular-arterial coupling (RVAC) in patients with APE, to determine their threshold values.Methods. We examined 34 patients with acute massive and submassive pulmonary embolism. The diagnosis was made on the basis of computed-tomography pulmonary angiogram. The mean age was 61 ±13 years. Of these, 16 were women (47,1%) and 18 were men (52,9%). As a control group, 30 healthy individuals were examined: 14 males and 16 females. The mean age of the healthy individuals was 39±9,8 years. Echocardiography was performed on Vivid E95 (GE HealthCare, USA) with data postprocessing on EchoPak workstation. The indices of right ventricular (RV) systolic and diastolic function, the magnitude of global longitudinal deformation of the right ventricle (GLS RV) and longitudinal deformation of the right ventricular free wall (RVFWLS) were studied using two-dimensional speckle-tracking echocardiography. We studied indices of right ventricular-arterial coupling (RVAC). We determined the relationship of longitudinal deformation of RV and RVAC with other indices of its systolic function. Results. Mean values of traditional parameters of RV contractile function were within normal limits, whereas mean values of longitudinal strain in APE were significantly lower than normal. There was also a significant decrease ( P &lt; 0,0001) of all measured parameters of right ventricular-arterial coupling in patients with APE in comparison with the control group.Conclusions. When longitudinal deformation parameters are included in the criteria of RV dysfunction in APE, its detectability increases from 26,47% to 61,77%. The revealed decrease of right ventricular-arterial coupling parameters in APE indicates a more frequent disturbance of the connection between RV and the small circle of blood circulation

Refined analysis of a supporting column assembly in a traditional Tibetan timber building and its limiting tilt angle before collapse

Traditional Tibetan architecture is an important part of the Chinese architecture. Many of the Tibetan structures are suffering from different types of damages after hundreds of years of service. The structural arrangement, types of damage and failure modes of these timber structures have been investigated on site. Tilting of structural members is found to be the most common type of damage. This paper studies the limiting inclination angle of a single-column supporting assembly of these structures before its collapse for proactive maintenance and restoration. A method to estimate the limiting tilt angle of the column is proposed based on the relationship between the lateral force, F, at the column head and the tilt angle, θ, of the column. Simplified analytical models of this column assembly in a traditional Tibetan timber building under in-plane and out-of-plane loadings respectively are proposed. The behavior of the constituting column foot joint, column-Queti joint and Queti-beam joint are analyzed in detail to obtain the global deformation and M-θ relationship of the column assembly under different loads. The F-θ relationship of the column assembly from the intact state to collapse is then obtained. A verified finite element model of the column assembly is adopted as reference to validate the performances of the proposed models throughout the loading process. Comparison of the F-θ curves obtained from the analytical models and the simulated results demonstrates the validity and accuracy of the proposed models. They may be adopted for a quick analysis of practical structures to estimate their limit states for health monitoring, maintenance and strengthening of structures.

Superior damage tolerance observed in interpenetrating phase composites composed of aperiodic lattice structures

Interpenetrating Phase Composite (IPC) metamaterials, based on lattice topologies, have garnered significant attention as advanced materials for structural applications. However, conventional IPCs, which rely on periodic lattice unit cells, are prone to catastrophic failure due to their global deformation modes. To overcome this limitation, we present a novel IPC design utilizing aperiodic truss unit cells, inspired by the elusive “Einstein” monotile pattern. Our concept is demonstrated through IPC 3D printed via polymer jetting, using a hard polymer as the lattice filler and a soft polymer as the matrix. The distinctive mechanical properties of IPCs are characterized through single and cyclic quasi-static compression testing. Our findings demonstrate that aperiodic IPCs enable progressive deformation with gradual compression stress plateaus. Additionally, aperiodic IPCs exhibit remarkable damage tolerance, retaining 67.59 % of residual energy absorption and 73.83 % of ultimate strength after multiple cyclic compressions up to 30 % strain. These mechanisms are attributed to the synergistic deformation of interconnected unit cells, which lead to self-adjusting plastic collapse, progressive displacement evolution and delocalized deformation. This aperiodic concept paves the way for developing high-performance cushioning protection materials.

Damage mitigation strategies for progressive collapse of modular steel buildings following sudden corner module removal

AbstractThis study evaluates gravity‐induced progressive collapse performance and damage mitigation strategies in modular steel buildings (MSBs) A typical three‐dimensional six‐story structure was modeled and analyzed using the finite element method, focusing on the instantaneous removal of a corner module. The study includes a parametric evaluation of the influence of beam moment capacity on progressive collapse and investigates the effect of using concrete as an infill for square hollow section columns. Additionally, the effectiveness of short K‐shaped braces in limiting gravity‐induced collapse was assessed. A response/damage index (DI) was proposed to quantify the overall structural response. The findings indicate that semirigid beam‐column connections outperform fully rigid connections. Both concrete‐filled columns and K‐shaped braces mitigate structural damage, with K‐shaped braces proving more effective in preventing collapse. Although increasing the beam moment‐resisting capacity reduced the DI, improvements were marginal beyond 50% of the fully rigid connection capacity. Higher beam moment capacities reduced local vertical displacement at the corner joint but led to undesirable lateral deformations. Reducing beam rigidity/capacity by 25% mitigated global structural deformations. The optimal beam moment capacity was identified as 75% of the total section capacity when using concrete‐filled columns. K‐shaped braces applied at the column midpoint entirely prevented progressive gravity‐induced collapse and no lateral deformations were observed in braced structures with fully rigid beam‐column connections, unlike unbraced structures. Concrete‐filled columns offer a cost‐effective solution for preliminary production of MSBs, while K‐shaped braces are suitable for retrofitting existing buildings. Further research is necessary to address other parameters influencing the mitigation of progressive collapse in MSBs.

A new finite element formulation for the lateral torsional buckling analyses of orthotropic FRP-externally bonded steel beams

Abstract The present study develops a new finite element (FE) formulation for the lateral torsional buckling (LTB) analyses of steel beams exteriorly bonded with orthotropic fiber-reinforced polymer (FRP) layers. The formulation considers shear deformations, partial material interaction, local and global warping deformations, and orthotropic FRP properties. The buckling responses of multispan FRP-bonded steel beams predicted by the present solutions are excellently validated against experiment and numerical solutions. As observed, the FRP strengthening is highly effective for the LTB resistance of steel beams. However, the LTB responses are strongly dependent on the orthotropic properties and strengthening lengths of FRP layers. The effects of shear deformations, span ratios, and loading conditions on the LTB responses are also quantified in the present study.

Novel symmetry corrugate hierarchical honeycomb for superior crashworthiness

Honeycombs are extensively utilized as energy absorber due to their stabilized mechanical properties. Therefore, we propose a novel symmetry-corrugate hierarchical design strategy to construct symmetry-corrugate hierarchical honeycombs (SCHH). Crashworthiness and mechanical properties of SCHH are investigated by experiments and numerical simulation. SCHH exhibits a stable and efficient mechanical property in the compression test. Furthermore, numerical simulations have been conducted to investigate the parametric design of SCHH. The results show the effects of different period coefficients φT and amplitude coefficients φA on deformation modes and crashworthiness. Specifically, as φT increases and φA decreases, the deformation changes from progressive deformation mode (P-mode) to mixed deformation mode (M-mode) to global bending deformation mode (G-mode). P-mode and M-mode have better crashworthiness. The effect of φT on the crashworthiness of SCHH is more significant than φA. In addition, SCHH provides the highest crashworthiness compared with other honeycombs. Specifically, the energy absorption capacity and crushing stability are improved by 53.8 % and 68.5 %, respectively, compared with conventional honeycomb. Eventually, a crashworthiness prediction model of SCHH is developed by machine learning algorithms, and the model is verified to have high accuracy. In this study, the proposed strategy and methods are expected to further improve the crashworthiness of honeycomb.

BOPVis: Bridge Monitoring Data Visualization for Operational Performance Mining

Bridges are fundamental facilities in the transportation system, and their operational performance is crucial for economic and social development. Many large bridges are now equipped with structural health monitoring (SHM) systems that collect various types of real-time data. However, our user study found that despite the accumulation of massive amounts of monitoring data, current analysis methods cannot efficiently process large-scale, high-dimensional data. To address this, we have developed BOPVis, a visualization system for bridge monitoring data. BOPVis allows users to intuitively locate sensors and extract corresponding data from a 3D digital model of a bridge. It also provides convenient and flexible interactions for examining trends over time and correlations across hundreds of monitoring channels. A real-world long-span suspension bridge in China is used as a case study to demonstrate the advantages of the BOPVis system for operational performance mining. Through BOPVis, the global temperature deformation behaviors of the bridge are explored and found to align with the physical mechanism documented in the SHM literature. The BOPVis system, with its interactive visualization analysis capabilities, offers a new method for analyzing bridge monitoring data.

Comprehensive investigation on modelling of low-velocity impact damage response of composite laminates − Experimental correlation and assessment

Low velocity impact (LVI) experiments are performed to provide correlations with the simulation results based on numerical modeling of the intralaminar matrix damage and interlaminar delamination damage of composite laminates. The good agreement between the numerical simulation and experimental results provided validation of the numerical modeling approach. The validated numerical modeling is then used in the parametrical assessment of the influence of material properties and model- related parameters on the global LVI deformation responses and the evolution characteristics of the intralaminar and interlaminar damage. It is observed that the element deletion method is not suitable to resolve the element distortion problem induced by the progressive damage. The numerical convergence problem caused by element distortion can be resolved with appropriate selection of threshold value of the critical damage parameter without element deletion. The parametrical numerical investigations showed that the variations of material properties and parameters related to interlaminar damage exhibited significant influence on the LVI global deformation responses and progressive damage evolutions. Meanwhile, insignificant influence of the material properties related to the intralaminar damage was observed for the normal variations within material scatters.