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Makale, WOS:000914155800001, This study conducted a comprehensive experimental and numerical assessment to investigate the effect of plastic circular balls placed in the middle of a section of a reinforced concrete slab on strength, ductility, thermal, and acoustic performance. The ball diameter/slab thickness (D/H), grades of concrete, and longitudinal tensile reinforcement ratio (q) in the slab were selected as the main variables. The variation in thermal and acoustic performance depending upon the ball’s diameter was investigated as well. The results showed that the slab’s load-carrying capacity, ductility, and energy dissipation capacity did not differ if the D/H ratio did not exceed 0.4; however, significant decreases in these values were observed when the D/H ratio exceeded 0.4. Moreover, the increase in the concrete and reinforcement’s strength had a negative effect on the slab with a D/H ratio of 0.8. The experimental results revealed that balled slabs are 3.15 times superior with respect to thermal conductivity and provide 1.38 times more insulation to absorb sound compared to nonballed slabs. In the numerical study of the slabs’ thermal performance, the mean surface temperature and heat flux on the slab where the heat transfer takes place decreased as the ball diameter increased. As seen in acoustic models, the level at which the slabs absorbed sound varied depending upon both the diameter of the balls and the sound frequency.

This study developed a finite element model according to higher-order shear deformation beam theory (HSDT) for the buckling analysis of functionally graded (FG) beams. Equilibrium equations of the FG beam are obtained from Lagrange’s equations. The beam element to be discussed within the scope of the study has 5 nodes and 16 degrees of freedom (DOF). As a result of the buckling analysis, the critical buckling load of the beam was obtained for various boundary conditions, power-law index (p), and slenderness (L/h). When the critical buckling loads obtained as a result of the analysis were compared with the literature, it was seen that they were quite compatible.

The architectural and physiomechanical properties of regenerative scaffolds have been shown to improve engineered tissue function at both a cellular and tissue level. The fabrication of regenerative three-dimensional scaffolds that precisely replicate the complex hierarchical structure of native tissue, however, remains a challenge. The aim of this work is therefore two-fold: i) demonstrate an innovative multidirectional freeze-casting system to afford precise architectural control of ice-templated collagen scaffolds; and ii) present a predictive simulation as an experimental design tool for bespoke scaffold architecture. We used embedded heat sources within the freeze-casting mold to manipulate the local thermal environment during solidification of ice-templated collagen scaffolds. The resultant scaffolds comprised complex and spatially varied lamellar orientations that correlated with the imposed thermal environment and could be readily controlled by varying the geometry and power of the heat sources. The complex macro-architecture did not interrupt the hierarchical features characteristic of ice-templated scaffolds, but pore orientation had a significant impact on the stiffness of resultant structures under compression. Furthermore, our finite element model (FEM) accurately predicted the thermal environment and illustrated the freezing front topography within the mold during solidification. The lamellar orientation of freeze-cast scaffolds was also predicted using thermal gradient vector direction immediately prior to phase change. In combination our FEM and bespoke freeze-casting system present an exciting opportunity for tailored architectural design of ice-templated regenerative scaffolds that mimic the complex hierarchical environment of the native extracellular matrix. STATEMENT OF SIGNIFICANCE: Biomimetic scaffold structure improves engineered tissue function, but the fabrication of three-dimensional scaffolds that precisely replicate the complex hierarchical structure of native tissue remains a challenge. Here, we leverage the robust relationship between thermal gradients and lamellar orientation of ice-templated collagen scaffolds to develop a multidirectional freeze-casting system with precise control of the thermal environment and consequently the complex lamellar structure of resultant scaffolds. Demonstrating the diversity of our approach, we identify heat source geometry and power as control parameters for complex lamellar orientations. We simultaneously present a finite element model (FEM) that describes the three-dimensional thermal environment during solidification and accurately predicts lamellar structure of resultant scaffolds. The model serves as a design tool for bespoke regenerative scaffolds.

The recent emergence of electric scooter (e-scooter) ride share companies has greatly increased the use of e-scooters in cities around the world. In this thesis, firstly, e-scooter injuries reported in the current literature as well as an overview of current e-scooter company policies, state laws, and local laws are reviewed. The most injured regions of the body were the head and extremities. These injuries are generally minor to moderate in severity and commonly include fractures and lacerations. A primary cause of e-scooter accidents is front wheel collisions with a vertical surface such as a curb or object, generically referred to as a "stopper." Therefore, various e-scooter-stopper crashes were simulated numerically across different impact speeds, approach angles, and stopper heights to characterize their influence on rider injury risk during falls. A finite element (FE) model of a standing Hybrid III anthropomorphic test device was used as the rider model after being calibrated against certification test data. The angle of approach was found to have the greatest effect on injury risk to the rider, and it was shown to be positively correlated with injury risk. Smaller approach angles were shown to cause the rider to land on their side, while larger approach angles caused the rider to land on their head and chest. Additionally, arm bracing was shown to reduce the risk of serious injury in two thirds of the impact scenarios. The majority of e-scooter rider fatalities (about 80%) are recorded in collisions between a car and an e-scooter. Therefore, crashes between an e-scooter and a sedan (FCR) and a sports utility vehicle (SUV) were simulated using finite element models. The vehicles impacted the e-scooter at a speed of 30 km/hr in a perpendicular collision and at 15 degrees towards the vehicle, to simulate a rider being struck by a turning vehicle. The risks of serious injury to the rider were low for the head, brain, and neck, but femur/tibia fractures were observed in all simulations. The primary cause of head and brain injuries was found to be the head-ground impact if such an impact occurred. Master of Science The recent emergence of electric scooter (e-scooter) ride share companies has greatly increased the use of e-scooters in cities around the world. In this thesis, firstly, e-scooter injuries reported in the current literature as well as an overview of current e-scooter company policies, state laws, and local laws are reviewed. The most injured regions of the body were the head and extremities. These injuries are generally minor to moderate in severity and commonly include fractures and lacerations. A primary cause of e-scooter accidents is front wheel collisions with a vertical surface such as a curb or object, generically referred to as a "stopper." Therefore, various e-scooter-stopper crashes were simulated numerically across different impact speeds, approach angles, and stopper heights to characterize their influence on rider injury risk during falls. A finite element (FE) model of a standing Hybrid III anthropomorphic test device was used as the rider model after being calibrated against certification test data. The angle of approach was found to have the greatest effect on injury risk to the rider, and it was shown to be positively correlated with injury risk. Smaller approach angles were shown to cause the rider to land on their side, while larger approach angles caused the rider to land on their head and chest. Additionally, arm bracing was shown to reduce the risk of serious injury in two thirds of the impact scenarios. The majority of e-scooter rider fatalities (about 80%) are recorded in collisions between a car and an e-scooter. Therefore, crashes between an e-scooter and a sedan (FCR) and a sports utility vehicle (SUV) were simulated using finite element models. The vehicles impacted the e-scooter at a speed of 30 km/hr in a perpendicular collision and at 15 degrees towards the vehicle, to simulate a rider being struck by a turning vehicle. The risks of serious injury to the rider were low for the head, brain, and neck, but femur/tibia fractures were observed in all simulations. The primary cause of head and brain injuries was found to be the head-ground impact if such an impact occurred.

(1) Background: to study the differences in flexural performance and failure characteristics of spontaneous combustion gangue coarse aggregate concrete (SCGAC) laminated slabs and ordinary concrete laminated slabs, comparative flexural performance tests of one ordinary concrete laminated slab and four spontaneous combustion gangue coarse aggregate concrete laminated slabs (SCGACLSs) full-scale specimens were carried out. (2) Methods: The loading method was four-point unidirectional static loading; the failure mode, load–deflection curve, load–reinforcement strain curve, and load–concrete strain curve of each specimen were analyzed. In addition, the load–deflection curve of the five slabs were predicted by ABAQUS. (3) Results: The five laminated slabs showed similar behaviors in terms of failure mode, load–strain curve, load–deflection curve, and deformation and all the properties satisfied the Chinese standard GB50010 (2010). Compared with ordinary concrete laminated slabs, the cracking load of SCGACLS with a precast layer of SCGAC(C30) decreased by 15.2% and the span deflection increased by 28.3% in the ultimate condition; however, when the strength grade of SCGAC of the precast layer was increased to SCGAC(C40), the cracking load increased by 7.8% and the span deflection was similar to that of the ordinary concrete laminated slabs. All specimens conformed to the planar section assumption. In addition, the finite element model (FEM) prediction results showed that the maximum relative errors of load and deflection were

Intervertebral disc (IVD) degeneration and regenerative therapies are commonly studied in organ-culture experiments with uniaxial compressive loading. Recently, in our laboratory, we established a bioreactor system capable of applying loads in six degrees-of-freedom (DOF) to bovine IVDs, which replicates more closely the complex multi-axial loading of the IVD in vivo. However, the magnitudes of loading that are physiological (able to maintain cell viability) or mechanically degenerative are unknown for load cases combining several DOFs. This study aimed to establish physiological and degenerative levels of maximum principal strains and stresses in the bovine IVD tissue and to investigate how they are achieved under complex load cases related to common daily activities. The physiological and degenerative levels of maximum principal strains and stresses were determined via finite element (FE) analysis of bovine IVD subjected to experimentally established physiological and degenerative compressive loading protocols. Then, complex load cases, such as a combination of compression + flexion + torsion, were applied on the FE-model with increasing magnitudes of loading to discover when physiological and degenerative tissue strains and stresses were reached. When applying 0.1 MPa of compression and ±2–3° of flexion and ±1–2° of torsion the investigated mechanical parameters remained at physiological levels, but with ±6–8° of flexion in combination with ±2–4° of torsion, the stresses in the outer annulus fibrosus (OAF) exceeded degenerative levels. In the case of compression + flexion + torsion, the mechanical degeneration likely initiates at the OAF when loading magnitudes are high enough. The physiological and degenerative magnitudes can be used as guidelines for bioreactor experiments with bovine IVDs., Journal of the Mechanical Behavior of Biomedical Materials, 143, ISSN:1751-6161, ISSN:1878-0180

International audience; The purpose of this study is to study the applicability of Discrete Ply Modeling (DPM) to crushing of composite tubes and to study the effect of stacking sequence and trigger geometry on the Specific Energy Absorption (SEA). The model was first validated with experimental results after which various stacking sequences were simulated to optimize it with an aim to increase the SEA.The stacking sequence [90/02/90/03/90/0/90] performed the best in terms of SEA value. As a result, the confidence of the DPM has been proven for some draping sequences but seems to be less confident to simulate the trigger effect.

The research project illustrates how performance-driven design tools can be conducted as an architectural design methodology that suggests an innovative approach to design a habitation shell in extreme environmental conditions without human assistance. This research study attempts to use environmental data revealed by NASA and its habitat design requirements to develop a conceptual design for an innovative habitation form and then simulate it with Mars conditions to analyze the habitation shell's structural behavior according to finite element analysis. In this regard, research phases, including layout configuration, form-finding, and structural analysis, have been conducted to explore a habitation concept implemented with generative design tools as a decision-maker in extreme conditions. In conclusion, two generated typologies of proposed habitation forms will be compared in terms of their structural performance under extreme loads of the martian environment. Within this research project, due to the numerous extreme challenges of design and construction of habitation in extreme conditions using conventional approaches, a performance-driven design methodology will provide a rational and sustainable design methodology to tackle extreme barriers to Mars's environment.

Introduction. Morphological and biomechanical features of the thoracolumbar junction determine the large number of cases of traumatic bone injuries. Reconstructive and stabilizing surgeries performed in this area, due to the significant load on both the elements of hardware and bony structures, require high reliability of fixation. Objective. To study the stress-strain state of the model of the thoracolumbar section of the spine after the Th12-L1 vertebrae resection with various options of transpedicular fixation under the influence of flexion load. Materials and methods. The stress-strain state of the mathematical finite-element model of the thoracolumbar section of the human spine under the influence of flexion load was studied. The model simulated the condition after surgery for a significant traumatic lesion of the thoracolumbar junction with laminectomy, facetectomy, and corpectomy of the Th12 and L1 vertebrae. Four variants of transpedicular fixation were studied (using short or long bicortical fixation screws, two crosslinks and without them). Control points of the model characterizing the load distribution both in bony structures and on metal elements of fusion and body replacement systems were studied. Results. Crosslinks have the greatest effect on reducing the level of stress both in the bony elements of the models and in the metal elements. When comparing the length of the screws, the use of monocortical screws was determined to have minor biomechanical advantages. The stress analysis of the area of the screw entry into the pedicle of the arch of the fixed vertebrae (clinically significant zone) revealed that in the model with short screws and without crosslinks, the stress for the vertebrae Th10, Th11, L2 and L3 is 5.0, 1.9, 7.8 and 13.6 MPa, respectively, while the presence of crosslinks reduces the corresponding values to 4.6, 1.9, 7.3 and 12.7 MPa. In models with bicortical screws, the corresponding values are 5.1, 2.3, 10.2, and 12.7 MPa in the absence of crosslinks and 4.7, 1.8, 9.9, and 12.2 MPa with the presence. A similar trend is observed in other control points. When comparing the results with the compression load in the models studied earlier, it was established that flexion causes an increase in the stress of the models with monocortical screws by an average of 33.7%, with bicortical screws by 39.6%. Conclusions. In case of flexion load, the use of crosslinks makes it possible to reduce the level of stress in all control points of the models, regardless of the length of the used transpedicular screws, while the length of the screws does not have a fundamental effect on the stress distribution., Морфологические и биомеханические особенности зоны грудо-поясничного перехода объясняют большое количество случаев костно-травматических изменений в ней. Реконструктивно-стабилизирующие хирургические вмешательства, выполняемые в этой зоне, из-за значительной нагрузки как на элементы металлоконструкций, так и на костные структуры, требуют высокой надежности фиксации. Цель: Изучить напряженно деформированное состояние модели участка грудо-поясничного отдела позвоночника после резекции позвонков Тh12-L1 при различных вариантах транспедикулярной фиксации под влиянием флексионной нагрузки. Материалы и методы. Исследовано напряженно-деформированное состояние математической конечно-элементной модели участка грудо-поясничного отдела позвоночника человека под влиянием изгибающей нагрузки. Модель имитировала состояние после хирургического вмешательства по поводу значительного травматического поражения участка грудо-поясничного перехода с ламинэктомией, фасетэктомией и корпектомией позвонков Th12 и L1. Изучали 4 варианта транспедикулярной фиксации (с использованием коротких или длинных бикортикальных фиксирующих винтов, двух поперечных стяжек и без них). Исследовали контрольные точки модели, характеризующие распределение нагрузки как в костных структурах, так и на металлических элементах стабилизирующей и телосменной систем. Результаты. Более всего на понижение уровня напряжения как в костных элементах моделей, так и в элементах конструкции, влияют поперечные стяжки. При сравнении длины винтов установлено, что использование монокортикальных винтов имеет незначительные биомеханические преимущества. Анализ напряжения участка входа винта в ножку дуги фиксированных позвонков (клинически значимой зоны) обнаружил, что у модели с короткими винтами без поперечных стяжек напряжения для позвонков Тh10, Тh11, L2 и L3 составляет 5,0, 1,9, 7,8 и 13,6 МПа соответственно, в то время как наличие поперечных стяжек снижает соответствующие показатели до 4,6, 1,9, 7,3 и 12,7 МПа. В моделях с бикортикальными винтами соответствующие показатели составляют 5,1, 2,3, 10,2 и 12,7 МПа при отсутствии стяжек и 4,7, 1,8, 9,9 и 12,2 МПа при наличии стяжек. Подобная тенденция наблюдается и в других контрольных точках. При сравнении результатов с компрессионной нагрузкой в моделях, исследованных ранее, выявлено, что флексия приводит к увеличению напряжения в моделях с монокортикальными винтами в среднем на 33,7%, с бикортикальными винтами – на 39,6%. Выводы. При флексионной нагрузке использование поперечных стяжек позволяет снизить уровень напряжения во всех контрольных точках моделей, независимо от длины использованных фиксирующих винтов, при этом длина винтов не влияет на распределение напряжения., Морфологічні та біомеханічні особливості зони грудо-поперекового переходу пояснюють велику кількість випадків кістково-травматичних змін у ній. Реконструктивно-стабілізувальні хірургічні втручання, які виконують у цій зоні, через значне навантаження як на елементи металоконструкцій, так і на кісткові структури, потребують високої надійності фіксації. Мета: Вивчити напружено-деформований стан моделі ділянки грудо-поперекового відділу хребта після резекції хребців Тh12-L1 за різних варіантів транспедикулярної фіксації під впливом флексійного навантаження. Матеріали і методи. Досліджено напружено-деформований стан математичної скінченно-елементної моделі ділянки грудо-поперекового відділу хребта людини під впливом згинального навантаження. Модель імітувала стан після хірургічного втручання з приводу значного травматичного ураження ділянки грудо-поперекового переходу із ламінектомією, фасетектомією та корпектомією хребців Th12 і L1. Вивчали 4 варіанти транспедикулярної фіксації (з використанням коротких або довгих бікортикальних фіксувальних гвинтів, двох поперечних стяжок та без них). Досліджували контрольні точки моделі, що характеризують розподіл навантаження як у кісткових структурах, так і на металевих елементах стабілізувальної та тілозамінної систем. Результати. Найбільше на зниження рівня напруження як у кісткових елементах моделей, так і в елементах конструкції, впливають поперечні стяжки. При порівнянні довжини гвинтів установлено, що використання монокортикальних гвинтів має незначні біомеханічні переваги. Аналіз напруження ділянки входу гвинта в ніжку дуги фіксованих хребців (клінічно значущої зони) виявив, що у моделі із короткими гвинтами без поперечних стяжок напруження для хребців Тh10, Тh11, L2 і L3 становить 5,0, 1,9, 7,8 та 13,6 МПа відповідно, тоді як наявність поперечних стяжок знижує відповідні показники до 4,6, 1,9, 7,3 і 12,7 МПа. У моделях із бікортикальними гвинтами відповідні показники становлять 5,1, 2,3, 10,2 та 12,7 МПа за відсутності стяжок і 4,7, 1,8, 9,9 та 12,2 МПа за наявності стяжок. Схожа тенденція спостерігається і в інших контрольних точках. При порівнянні результатів із компресійним навантаженням у моделях, досліджених раніше, виявлено, що флексія спричиняє збільшення напруження у моделях із монокортикальними гвинтами в середньому на 33,7%, з бікортикальними гвинтами ‒ на 39,6%. Висновки. При флексійному навантаженні використання поперечних стяжок дає змогу знизити рівень напруження в усіх контрольних точках моделей незалежно від довжини використаних фіксувальних гвинтів, при цьому довжина гвинтів не впливає на розподіл напруження.

At present, there is a lack of research on the influence of different dynamic constitutive models of steel and concrete on the dynamic mechanical properties of concrete-filled steel tubular (CFST) columns under lateral impact. In this paper, A comprehensive numerical study on the effects of different dynamic constitutive models of steel and concrete on the lateral impact response of CFST columns was conducted. The dynamic constitutive models of steel and concrete with different strengths were divided into four categories, namely, normal-strength steel, high-strength steel, normal-strength concrete and high-strength concrete. The established finite element model of CFST columns considering the progressive damage degradation of steel as well as the compressive and tensile damage factors of concrete was verified against published experimental data. Based on the verified FE model, the effects of different dynamic constitutive models of steel and concrete on the impact response of circular CFST columns were analyzed. The analyzed results show that the different dynamic constitutive models of steel have different effects on the impact force and mid-span time-history deflection curves of CFST columns. The analysis result, ignoring the effect of concrete strain rate, is in good agreement with the CEB-FIP model considering the effect of steel strain rate. This is because the largest proportion of the impact energy of CFST members is mainly assimilated by the outer steel tube.

Fractures at the thoracolumbar junction are the most common traumatic spinal injuries. Advances in instrumentation for vertebral body replacement have significantly improved surgical techniques.However, the biomechanical characteristics of stabilizing surgeries have been insufficiently studied. Objective. To investigate the stressstrain state (SSS) of a mathematical finite element model of the humanthoracolumbar spine during trunk backward bending after ТhХІІ vertebra resection, considering different transpedicular fixation options. Methods. A mathematical finite element model of the humanthoracolumbar spine — ThIX‒LV vertebrae — was developed. The ТhХІІ vertebra was removed, and an interbody support and transpedicularsystem with 8 screws were implanted to simulate the postsurgical state after a ТhХІІ burst fracture with wide laminectomy, facetectomy, and corpectomy. The influence of transpedicular screw length and the presence of cross-links on the SSS of the model wasexamined. Results. The use of bicortical screws reduced stress levels in the bone elements of the model, except in the regions around the screws in the lumbar vertebrae, when compared to short screws.Installing cross-links decreased stress levels at all control points compared to models without cross-links. Specifically, in the presence of cross-links, the SSS values at the entry points of the short screwsinto the vertebral bodies of ThX, ThXI, LI, and LII were 2.3, 1.8, 1.2, and 5.0MPa, respectively, compared to 2.7, 2.0, 1.5, and 6.1 MPa in the models without cross-links. In the case of bicortical screwswithout cross-links, the stress values at the screw entry points into the pedicles of the corresponding vertebrae were 2.9, 1.5, 8.2, and 11.2 MPa, respectively, compared to 2.7, 1.5, 7.5, and 10.2 MPa in the models with cross-links. Conclusions. When the trunk is tilted backward, the use of cross-links reduces stress levels at all control points in the models, regardless of the screw length used. Bicortical transpedicular screws increase stress levels on the screws themselves and in the lumbar vertebral bodies surrounding them., Переломи ділянки грудопоперекового переходу є найчастішими травматичними ураженнями хребта. Удосконалення систем стабілізації та конструкцій для заміни тіл хребців значнопокращило техніку хірургічних утручань. Але особливості біомеханіки варіантів стабілізувальних операцій вивчені недостатньо. Мета. Вивчити напружено-деформований стан(НДС) моделі грудопоперекового відділу хребта під час нахилу тулуба назад після резекції хребця ТhХІІ за різних варіантів транспедикулярної фіксації. Методи. Розроблено математичнускінченно-елементну модель грудопоперекового відділу хребта людини — хребці ТhІХ‒LV. Хребець ТhХІІ видалено і встановлено міжтілову опору та траспедикулярну систему із 8 гвинтів.Тобто, імітовано стан після хірургічного втручання з приводу вибухового перелому ТhХІІ із широкою ламінектомією, фасетектомією та корпектомією. Досліджували вплив на НДС моделі довжини транспедикулярних гвинтів і поперечних стяжок.Результати. Застосування бікортикальних гвинтів дозволило знизити рівень напружень у кісткових елементах моделі порівняно з короткими, за винятком зон навколо гвинтів у хребцяхпоперекового відділу. Установлення поперечних стяжок, порівняно з моделями без них, зменшило рівень напружень на всіх контрольних точках. Зокрема, за наявності стяжок показникиНДС на рівні входу короткого гвинта в тіла хребців ТhХ, ТhХІ, LІ та LІІ становили 2,3; 1,8; 1,2; 5,0 МПа відповідно проти 2,7; 2,0; 1,5; 6,1 МПа в моделі без стяжок. У разі введення бікортикальних гвинтів без стяжок у ділянках входу гвинта в ніжкудуги відповідних хребців напруження дорівнювали 2,9; 1,5; 8,2; 11,2 МПа проти 2,7; 1,5; 7,5; 10,2 МПа в моделі зі стяжками. Висновки. За умов нахилу тулуба назад використання поперечних стяжок дозволяє знизити рівень напружень у всіх контрольних точках моделей незалежно від довжини використанихгвинтів. Застосування бікортикальних транспедикулярних гвинтів призводить до підвищення рівня напружень на них танавколо в тілах хребців поперекового відділу хребта.

As the core component of a wind turbine, the performance of main shaft bearings directly affects the transmission efficiency and reliability of wind turbines. To the best of our knowledge, few reliability analyses of wind power bearings have been carried out with the consideration of mechanical properties. In this paper, a finite element model is established to calculate the subsurface stress of the main shaft bearing of a wind turbine, considering the structural thicknesses, the friction conditions, and the interference conditions of the bearing. The randomness of several factors is considered, including structural thicknesses, material parameters, friction coefficients and the interference of the bearing. Latin hypercube design is used to get sample points, and the bearing’s mechanical responses of these sample points are analyzed. Through the data of these sample points, a Kriging model is established. The comparison with the finite element results shows that the Kriging model greatly improves the computational efficiency of the finite element model, with a relative error result of only 3.80 × 10−5. The Monte Carlo simulation method is applied to analyze the reliability and sensitivity of the bearing’s subsurface stress. The results show that an increase in the inner ring thickness will improve the bearing’s stress reliability, while an increase in other parameters will reduce the bearing’s stress reliability, including outer ring thickness, roller length, material elastic modulus, density, bearing and stationary shaft interference, and friction coefficients. The research results provide a reasonable reference for optimizing the design of the structure, assembly and material selection for main shaft bearings of wind turbines.

In the process of high flow rate fracture and high gas production, the sealing performance of the premium connection decreases due to the dynamic load and vibration of downhole tubing strings, which may cause accidents. Existing static analysis methods cannot effectively explain this phenomenon. The main objective of this paper is to propose a novel analytical method for evaluating the sealing performance of a premium connection. In this paper, a dynamic model of sealing surfaces of the premium connection is established based on the vibration equation of elastic rod, and the hysteresis characteristics and energy dissipation mechanism of sealing surfaces are analyzed. Considering the influence of spherical radius, internal pressure, axial cyclic load amplitude, and modal vibration, a spherical-conical premium connection finite element model is established to analyze the influence laws of the connection’s energy dissipation and sealing performance. The results show that the sealing performance of the premium connection under dynamic load can be effectively analyzed by using energy dissipation theory compared with traditional static contact analysis. Compared with the vibration of the tubing string, the dynamic loads caused by the change of fluid pressure and flow rate in the tubing string have a significant influence on the connection’s sealing performance. When the internal pressure and axial cyclic loads are 80 MPa, 400 kN, or 60 MPa and 500 kN respectively, serious plastic deformation occurs in the thread and sealing surfaces, and the energy dissipation of the sealing surfaces increases significantly, which could lead to sealing failure.

Inspired by the bionic Bouligand structure, helicoidal carbon fiber-reinforced polymer composite (CFRPC) laminates have been proven to own outstanding out-of-plane mechanical properties. This work aims to further explore the excellent bending characteristics of helicoidal CFRPC laminated plates and find out the optimal helicoidal layup patterns. The optimization design of laminated plates stacked with single-form and combination-form helicoidal layup sequences are carried out by using the finite element method (FEM) and adaptive simulated annealing (ASA) optimization algorithm on the Isight platform. Then, the nonlinear bending responses of optimal helicoidal CFRPC laminated plates are investigated via the FEM for the first time. The helicoidal CFRPC laminated plates under three different types of boundary conditions subjected to transverse uniformly distributed load are considered. The numerical results reveal that the combination-form helicoidal layup sequences can decrease the dimensionless bending deflection of laminated plates by more than 5% compared with the quasi-isotropic plate and enhance the out-of-plane bending characteristics of CFRPC laminated plates effectively. The boundary conditions can significantly influence the nonlinear bending responses of helicoidal CFRPC laminated plates.

This deliverable 4.4 Risk Management is published under WP4Control and real-time simulation of the construction of the ASHVIN project. Abstract In order to develop comprehensive digital-twin supported site risk management regime it is important to collect data on productivity from well-documented previous construction activities. One of the highest risk activities in construction relates to unknown or unanticipated soil conditions. Soils are naturally occurring, variable materials whose properties depend on stress and strain level and vary temporally. Current design methods deal with uncertainty by assuming conservative estimates of soil properties and calculating the response of the geotechnical structure to some unlikely set of extreme loads. In certain analyses involving soil-structure interaction problems (e.g. soil retaining structures) the loads experienced by structural elements (such as piles, anchors, walls etc.) are directly related to the displacements (strains) experienced. Therefore, only a model that uses the most-likely soil and structure properties at any given point in the life-cycle of a structure to accurately predict the displacement can allow the real safety level (resistance to additional loading) of a structure to be determined. This deliverable uses monitoring data collected from the construction of a deep sea quay wall to determine the real safety level of the wall throughout the construction programme. An advanced finite element model is implemented that can capture the real response. By comparing the measured and predicted response of the wall, a number of updates are initiated that incorporate the knowledge gathered and allow for reduction of uncertainty in a logical and consistent manner. The development of Ports is driven by ever increasing vessel sizes. To replace an existing quay wall to allow for larger vessels means an investment of several 100 million euros and a significant environmental cost in terms of CO2 emissions from new construction. In this report the digital twin developed demonstrated the safety level of the existing wall to several metres of additional dredging.

Objective: to study the stress-strain state of the hip joint elements in cases of different localization of the destruction of the femoral head due to aseptic necrosis in children with lesions 50 and 75 % of its volume. Methods: on mathematical models of the hip joint, the stress-strain state was investigated in the case of femoral head defects of 50 and 75 % of its volume of various localization. The model consisted of components with the properties of cancellous and compact bone tissue, as well as with growth zones with the mechanical characteristics of cartilage. The models were loaded with a vertical distributed force of 270 N. Reproduced the action m. gluteus medius of 450 N and m. gluteus minimus force of 200 N. Results: when we increased the area of the femoral head defect up to 50 % at weight bearing on a limb the values of maximum stresses increased in all studied areas of the model compared to the normal state and the case of 25 % defect. At increased defect upto 75 % in the critical zone, the stress-strain state reached the number of 31.9 MPa, stress increased on its lateral edge in the cortical layer up to 25.6 MPa, and in the cancellous boneup to 9.1 MPa. Stress decreased on the medial edge of the defect to 5.0 MPa in the cortical layer and up to 0.8 MPa — in the cancellous bone. Near the middle part of the defect stress increased in the cortical layer to 4.8 MPa, and in the cancellous bone decreased to 0.8 MPa. Conclusions: in the models with a lesions size of 50 and 75 %, the most unfavorable is the location of the defect on the border of the upper edge of the acetabulum and the upper part of the femoral head, in the zone of its greatest load. If the volume of the femoral head goes up to 50 %, with the weight bearing on the limb the values of maximum stresses increase practically on all studied areas of the hip joint model. The size of the lesion of the femoral head up to 75 % leads to an increasing of magnitude of the stresses in the loaded areas and to a decreasing in other investigated areas., Цель: изучить напряженно-деформированное состояние (НДС) компонентов тазобедренного сустава в случаях различной локализации разрушения головки бедренной кости (ГБК) вследствие асептического некроза у детей с поражением 50 и 75 % от ее объема. Методы: на математических мо­делях тазобедренного сустава исследовано НДС в случае дефектов ГБК 50 и 75 % от ее объема различной локализации. В состав модели входили компоненты со свойствами губчатой и компактной костной ткани, а также зоны роста с механическими характеристиками хряща. Модели нагружали вертикальной распределенной силой величиной 270 Н. Воспроизводили действие m. gluteus medius силой 450 Н и m. gluteus minimus силой 200 Н. Результаты: при увеличении величины дефекта головки бедренной кости до 50 % от площади ее суставной поверхности при опоре на конечность возрастают величины максимальных напряжений практически на всех исследованных участках модели по сравнению с нормой и случаем с дефектом 25 %. При увеличении дефекта до 75 % в критической зоне НДС достигло показателя 31,9 МПа, по его латеральному краю отмечено увеличение величины напряжений в корковом слое до 25,6 МПа, а в губчатой кости — до 9,1 МПа. По медиальном краю дефекта зафиксировано уменьшение величин напряжений до 5,0 МПа в корковом слое и до 0,8 МПа — в губчатой кости. Вблизи средней части дефекта напряжение возросло в корковом слое до 4,8 МПа, а в губчатой кости снизилось до 0,8 МПа. Выводы: в моделях с объемом поражения ГБК 50 и 75 % наиболее неблагоприятным является расположение дефекта на границе верхнего края вертлужной впадины и верхней части ГБК, в зоне ее наибольшей нагрузки. Если объем поражения ГБК достигает 50 %, при опоре на конечность возрастают величины максимальных напряжений практически на всех исследованных участках модели ТБС. Увеличения размера поражения ГБК до 75 % приводит к повышению величин напряжений в нагружаемых участках и к снижению в других исследованных зонах., Мета: вивчити напружено-деформований стан (НДС) компонентів кульшового суглоба у випадках різної локалізації руйнування головки стегнової кістки (ГСК) унаслідок асептичного некрозу в дітей із ураженням 50 і 75 % від її обсягу. Методи: на математичних моделях кульшового суглоба досліджено НДС у разі дефектів ГСК 50 і 75 % від її обсягу різної локалізації. До складу моделі входили компоненти з властивостями губчастої та компактної кісткової тканини, а також зони росту з механічними характеристиками хряща. Моделі навантажували вертикальною розподіленою силою величиною 270 Н. Відтворювали дію m. gluteus medius силою 450 Н і m. gluteus minimus силою 200 Н. Результати: у разі збільшення величини дефекту головки стегнової кістки до 50 % від площі її суглобової поверхні під час опори на кінцівку зростають величини максимальних напружень практично на всіх досліджених ділянках моделі порівняно з нормою і випадком із дефектом 25 %. За умов збільшення дефекту до 75 % у критичній зоні НДС досяг показника 31,9 МПа, на його латеральному краї відзначено збільшення величини напружень у корковому шарі до 25,6 МПа, а в губчастій кістці — до 9,1 МПа. По медіальному краю дефекту зафіксовано зменшення величин напруження до 5,0 МПа в корковому шарі і до 0,8 МПа — в губчастій кістці. Поблизу середньої частини дефекту напруження зросло в корковому шарі до 4,8 МПа, а в губчастій кістці знизилося до 0,8 МПа. Висновки: у моделях з обсягом ураження ГСК 50 і 75 % найнесприятливішим є розташування дефекту на межі верхнього краю кульшової западини та верхньої частини ГСК, у зоні її найбільшого навантаження. Якщо обсяг ураження ГСК досягає 50 %, за умов опори на кінцівку зростають величини максимальних напружень практично на всіх досліджених ділянках моделі КС. Збільшення розміру дефекту ГСК до 75 % призводить до підвищення величин напружень у ділянках, які зазнають навантаження, та до зниження в інших досліджених зонах.

In the United States pedestrian fatalities in vehicle impacts have increased over the last 40 years and pedestrians who use wheelchairs (seated pedestrians) have higher mortality rates than standing pedestrians in vehicle impacts. Standing pedestrian protection has generated increased attention and regulatory action but seated pedestrian protection has not been investigated or regulated. To investigate standing pedestrian safety researchers use finite element models of the human body and simulate vehicle impacts. Finite element models can be useful but they are limited by their biofidelity, and often simplify the complex anatomy of the human body for the sake of computational expense. If modeling results are to be taken seriously to investigate standing and seated pedestrian protection, then further model development and validation is necessary. In this dissertation a finite element model of a male 50th percentile standing pedestrian was enhanced and validated for use in vehicle impact simulations. The standing pedestrian model lower body was further enhanced and validated to study the importance of stabilizing components of the knee. These updates to the standing pedestrian knee joint were imported into an occupant model and further validated in occupant loading scenarios. The updated standing pedestrian was used to explore the effect of modeling component failure on vehicle impact. Simplified and detailed occupant models were used to model seated pedestrians in vehicle impacts to explore seated pedestrian injury risks. The seated pedestrian head and brain typically reported the highest risks of injury, usually because of head-ground contact. A lap belt, airbag vest, and bicycle helmet were tested on the seated pedestrians. The lap belt and airbag vest typically increased injury risks and the bicycle helmet reduced injury risks. The work presented in this dissertation may inform future modelers, vehicle designers, and safety equipment developers on standing and seated pedestrian safety. Doctor of Philosophy In the United States pedestrian fatalities in vehicle impacts have increased over the last 40 years and pedestrians who use wheelchairs (seated pedestrians) have higher death rates than standing pedestrians in vehicle impacts. Research studies have examined how to protect standing pedestrians, but not seated pedestrians. The goal of this work was to begin investigating seated pedestrian safety. To investigate standing pedestrian safety researchers use computer models (finite element models) of the human body and simulate vehicle impacts. These finite element models can be useful but they are limited by how life like they are. If modeling results are to be taken seriously to investigate standing and seated pedestrian protection, then further model improvement is necessary. In this dissertation a finite element model of an average North American male standing pedestrian was improved for use in vehicle impact simulations. The standing pedestrian model lower body was further improved to study the importance of stabilizing components of the knee. These updates to the standing pedestrian knee joint were imported into a seated model with the same anatomy. Simplified and detailed seated models were used to model seated pedestrians in vehicle impacts to explore seated pedestrian injury risks. The seated pedestrian head and brain typically reported the highest risks of injury, usually because of head-ground contact. A lap belt, airbag vest, and bicycle helmet were tested on the seated pedestrians. The lap belt and airbag vest typically increased injury risks and the bicycle helmet reduced injury risks. The work presented in this dissertation may inform future modelers, vehicle designers, and safety equipment developers on standing and seated pedestrian safety.

Incremental sheet forming (ISF) is an emerging technology that has shown great potential in forming customized three-dimensional (3D) parts without the use of product-specific dies. The forming force is reduced in ISF due to the localized nature of deformation and successive forming. Forming force plays an important role in modeling the process accurately, so it needs to be evaluated accurately. Some attempts have been made earlier to calculate the forming force; however, they are mostly limited to empirical formulae for evaluating the average forming force and its different components. The current work presents a mathematical model for force prediction during ISF in a 3D polar coordinate system. The model can be used to predict forces for axis-symmetric cones of different wall angles and also for incremental hole flanging. Axial force component, resultant force in the r-θ plane, and total force have been calculated using the developed mathematical model appearing at different forming depths. The cone with the same geometrical parameters and experimental conditions was modeled and simulated on ABAQUS, and finally, experiments were carried out using a six-axis industrial robot. The mathematical model can be used to calculate forces for any wall angle, but for comparison purposes, a 45° wall angle cone has been used for analytical, numerical, and experimental validation. The total force calculated from the mathematical model had a very high level of accuracy with the force measured experimentally, and the maximum error was 4.25%. The result obtained from the FEA model also had a good level of accuracy for calculating total force, and the maximum error was 4.89%.

In the modelling of reinforced concrete (RC) buildings, the rigid diaphragm hypothesis to represent the in-plane behavior of floors was and still is very commonly adopted because of its simplicity and computational cheapness. However, since excessive floor in-plane deformability can cause a very different redistribution of lateral forces on vertical resisting elements, it may be necessary to consider floor deformability. This paper investigates the classical yet intriguing question of modeling orthotropic RC floor systems endowed with lightening elements by means of a uniform orthotropic slab in order to describe accurately the building response under seismic loads. The simplified method, commonly adopted by engineers and based on the equivalence between the transverse stiffness of the RC elements of the real floor and those of the orthotropic slab, is presented. A case study in which this simplified method is used is also provided. Then, an advanced finite element (FE)-based method to determine the elastic properties of the equivalent homogenized orthotropic slab is proposed. The novel aspect of this method is that it takes into account the interaction of shell elements with frame elements in the 3D FE model of the building. Based on the results obtained from the application of this method to a case study, a discussion on the adequacy of the simplified method is also provided.

Inspired by the macro- and microstructures of the lotus leaf, a series of biomimetic hierarchical thin-walled structures (BHTSs) was proposed and fabricated, exhibiting improved mechanical properties. The comprehensive mechanical properties of the BHTSs were evaluated using finite element (FE) models constructed in ANSYS, which were validated by the experimental results. Light-weight numbers (LWNs) were used as an index to assess these properties. The simulation results were compared with the experimental data to validate the findings. The compression results indicated that the maximum load carried by each BHTS was very similar, with the highest bearing load being 32,571 N and the lowest being 30,183 N, resulting in only a 7.9% difference between them. In terms of the LWN-C values, the BHTS-1 exhibited the highest value at 318.51 N/g, while the BHTS-6 had the lowest value at 295.16 N/g. For the torsion and bending results, these findings suggested that increasing the bifurcation structure at the end side of the thin tube branch significantly improved the torsional resistance properties of the thin tube. For the impact characteristics of the proposed BHTSs, enhancing the bifurcation structure at the end of the thin tube branch significantly increased the energy absorption capacity and improved the energy absorption (EA) and the specific energy absorption (SEA) values of the thin tube. The BHTS-6 had the best structural design in terms of both the EA and SEA among all the BHTSs, but its CLE value was slightly lower than that of the BHTS-7, indicating slightly lower structural efficiency. This study provides a new idea and method for developing new lightweight and high-strength materials as well as designing more effective energy absorption structures. At the same time, this study has important scientific value in understanding how biological structures in nature exhibit their unique mechanical properties.

(English) Unreinforced masonry buildings (URM), which prevail in many historic and urban centres, can be considered to be significantly vulnerable to seismic actions due to their peculiar constructive and structural features that could influence their seismic performance, even in low to moderate seismic hazard areas. These existing structures were usually designed considering only gravity loads without any seismic design requirements. Hence, they may endure severe consequences in the event of an earthquake due to the presence of many specific sources of structural vulnerability, such as the material's limited resistant capacity and ductility, the buildings’ height, very slender load-bearing walls, semi-flexible horizontal diaphragms, irregular plan configurations, presence of vertical extensions, large façade openings, among other structural features.The scientific literature currently offers a variety of methods for assessing seismic vulnerability of existing buildings on a large scale, as it is considered a challenging task. The selection of the appropriate approach is determined by several factors, including the purpose and nature of the study, the amount of data and resources available, the investigated building typologies, the level of analysis effort, and the cost required for the studies.The aim of this research is to contribute to the seismic vulnerability assessment of existing masonry buildings of the Eixample district of Barcelona, though the derivation of a general methodology, intensively based on numerical simulation due to lack of seismic damage observations from past earthquakes. This approach could be applied to similar problems involving the vulnerability assessment of historic urban centres in low to moderate seismic regions, by applying the necessary modifications. The first step of the proposed methodology is elaborating a detailed building taxonomy of the masonry buildings of the Eixample district according to their structural, material and geometrical characteristics, relevant to their seismic behaviour and possible sources of vulnerability. The most representative building typologies are selected based on the aforementioned building taxonomy, by using available statistical data of structural features of the analysed building stock. The next step is developing sophisticated numerical models of the previously identified representative masonry buildings, by using an efficient and realistic simulation of their seismic response based on the Finite Element Method (FEM). Non-linear static (pushover) analysis are performed for both main directions (parallel and perpendicular to the façade) in order to better understand their global seismic behaviour in terms of capacity and failure mechanisms. Moreover, parametric analyses are carried out to investigate the influence of different structural parameters on the building’s seismic performance. The N2 method is applied for the evaluation of the buildings’ seismic performance for the seismic hazard scenarios in Barcelona. The final step is the proposal of new forms of the Vulnerability Index Method (VIM) for both main directions, by defining the classes and calibrating the weights of the specific vulnerability parameters. The methodology is applied eventually to the Eixample district of Barcelona’s urban centre, by including two cases: a large number of existing masonry buildings and a typical urban block. (Español) Los edificios de obra de fábrica no armada (URM), abundantes en muchos centros urbanos históricos, resultan frecuentemente vulnerables ante las acciones sísmicas, incluso en zonas de baja o moderada peligrosidad sísmica, debido a sus características constructivas y estructurales. Por lo general, estas estructuras fueron diseñadas teniendo en cuenta únicamente las cargas gravitatorias y sin verificar su comportamiento sísmico. Ante un terremoto, dichas estructuras pueden sufrir graves consecuencias debido a varias fuentes específicas de vulnerabilidad estructural, como son la limitada capacidad resistente y limitada ductilidad del material, la altura de los edificios, los presencia de muros de carga muy esbeltos, forjados flexibles o semiflexible, las configuraciones de planta, frecuentemente irregulares, la presencia de extensiones verticales (remontas) y la frecuente presencia de grandes aberturas de fachada, entre otras.Como consecuencia del desafío que supone la evaluación de la vulnerabilidad sísmica de los edificios existentes a gran escala, en la literatura científica actual se han propuesto una gran variedad de métodos orientados hacia su caracterización. La selección del método más adecuado viene determinada por varios factores, entre los cuales se hallan el propósito y la naturaleza del estudio, la cantidad de datos y de recursos disponibles, las tipologías de los edificios investigados, el esfuerzo computacional requerido para el análisis y el coste de la investigación.El objetivo del presente trabajo reside en contribuir a la evaluación de la vulnerabilidad sísmica de los edificios de obra de fábrica existentes en el distrito del Eixample de Barcelona. Ello se lleva a cabo mediante la elaboración de una metodología general basada principalmente en la simulación numérica debido a la ausencia de observaciones, en el caso investigado, relativas a daños sísmicos producidos terremotos ocurridos en el pasado. Esta metodología podría aplicarse, con las modificaciones necesarias, a casos similares relativos a la evaluación de la vulnerabilidad de centros urbanos históricos en regiones de sismicidad baja a moderada. El primer paso de la metodología propuesta consiste en elaborar una taxonomía detallada de los edificios de obra de fábrica del distrito del Eixample en función de las características estructurales, materiales y geométricas que resultan relevantes para la caracterización de comportamiento sísmico. Los tipos de edificios más representativos se han seleccionado en base a dicha taxonomía, utilizando para ello datos estadísticos disponibles sobre sus características estructurales. El siguiente paso ha consistido en desarrollar modelos numéricos avanzados de los edificios seleccionados. Para este fin se ha utilizado el Método de los Elementos Finitos (MEF) por su simulación eficiente y realista de la respuesta sísmica. Se han realizado análisis estáticos no lineales (pushover) para las dos direcciones principales (paralela y perpendicular a la fachada) de los edificios, con el fin caracterizar su comportamiento sísmico global en términos de capacidad y mecanismos de fallo. Además, se han realizado análisis paramétricos con la finalidad de investigar la influencia de diferentes parámetros estructurales en el comportamiento sísmico. Se ha aplica el método N2 para la evaluación del comportamiento sísmico de los edificios para distintos escenarios de peligrosidad sísmica en Barcelona. Finalmente, se han propuesto unos formularios modificados para la aplicación del Método del Índice de Vulnerabilidad (VIM) según las dos direcciones principales, de los edificios. Ello ha comportado una definición de las clases de vulnerabilidad y la calibración de los pesos de los parámetros específicos de vulnerabilidad consistentes en (1) un conjunto amplio de edificios de obra de fábrica existentes y (2) el caso específico de un bloque de edificios típico del entorno urbano investigado. Finite Element Model, Pushover Analysis, N2 method, Vulnerability Index Method.

Reduction of tire/road noise has become an important issue for EVs since powertrain noise has largely been eliminated. A tire’s air-cavity mode is known to be a significant contributor to increased forces at the wheel hub, which can result in significant interior noise levels near 200 Hz. Moreover, the single natural frequency of a static, undeformed tire can separate into two neighboring frequencies for a rolling, deformed tire due to the combination of the tire’s asymmetry, and the Doppler effect resulting from the tire’s rotation. In this study, the evolution of the Doppler-related frequency split with increasing speed was observed in Tire Pavement Test Apparatus (TPTA) tests by measuring the dynamic force at the hub under rotation and load. Similar results were obtained using FE simulations. Through the FE simulation, it has been shown that there can be force amplification at the hub when the split frequencies couple with adjacent treadband structural modes near 200 Hz. In addition, material modifications were applied to the base model in the simulations to find values that would reduce force levels at the split frequencies. Finally, it is suggested that a target speed needs to be determined when evaluating a tire since the two split, natural frequencies are strongly influenced by rotation speed.

This paper proposes a Bayesian RC-frame finite element model updating (FEMU) and damage state estimation approach using the nonlinear acceleration time history based on nested sampling. Numerical RC-frame finite element model (FEM) parameters are selected through nested sampling, and their probability density is estimated using nonlinear time history. In the first step, we estimate the error standard deviation and select the FEM parameters that are required to be updated by FEMU. In the second step, we estimate the probability density of the selected parameters and realize the FEMU through the resampling method and kernel density estimation (KDE). Additionally, we propose a damage state estimate approach, which is a derivative method of the FEMU sample. The numerical results demonstrate that the proposed approach is reliable for the Bayesian FEMU and damage state estimation using nonlinear time history.

Due to the excitation generated by the periodically alternate pumping of dual-hydraulic cylinders, vibration of concrete pump trucks (CPT) occurs. Excessive boom vibration will seriously affect the service life and operation safety of CPT. At the same time, the long boom structure of a CPT makes it very sensitive to the posture and pumping conditions, which directly affect the vibration characteristics of CPT in different postures and different working conditions. This paper establishes a finite element model of a type of CPT. Through force analysis of concrete in the straight pipe and elbow pipe during the pumping and reversing stages, an excitation model of the conveying pipe is established. Based on the secondary development of HyperWorks, a finite element model of CPT with multiple postures is built, and the dynamic response under multiple conditions is analyzed. Finally, the accuracy of the finite element model of CPT and the excitation model of the conveying pipe is verified by experiment.

Foundations supporting infrastructure built on soft and compressible marine soil are unlikely to sustain due to possibility of undrained shear failure or excessive settlement of the supporting soil. This necessitates the importance of implementing an adequate ground improvement strategy. Among different techniques, soft soil reinforcing by the installation of stone columns is one of the most successful methods in terms of long-term stability of foundations. To investigate the load-settlement characteristics of such reinforced soil, a group of closely spaced stone columns was constructed at a location along the eastern coast of Australia. The site geology revealed thick layers of soft, compressible marine clay deposit. These stone columns were loaded by constructing earthen embankment and the resulting load-settlement characteristics were measured by an array of sensors. A two-dimensional plane strain analysis was performed using finite element modeling simulations. Comparison of numerical results with the field data demonstrated accuracy of the numerical model. Additional studies were carried out to investigate the efficiency of the model. This paper integrates the new findings from the full-scale field study and advanced numerical simulations while drawing pertinent conclusions.

Unlike steel reinforcements in concrete, Fiber Reinforced Polymer (FRP) materials are light and free from corrosion. Therefore, FRP materials are increasingly being used in structural engineering as a replacement for steel reinforcements. While the use of FRP bars as longitudinal reinforcements in concrete deep beams has been studied somewhat widely, their use and effectiveness as web reinforcements are not well studied. In this study, the effect of the FRP web reinforcements on the behaviour and strength of FRP-reinforced concrete deep beams were investigated in an experimental study. Four glass fiber-reinforced concrete (RC) simply supported deep beam specimens were tested under a concentrated load with different shear span-to-depth ratios and web reinforcement ratios. The behaviour of the deep beams was described in terms of load–deflection behaviour, crack developments, strain in FRP reinforcements, and failure modes. The experimental investigation emphasized the significance of web reinforcements in determining the reinforced concrete deep beam behaviour, such as mid-span deflection, crack breadth, failure modes, and ultimate strengths. Furthermore, to predict the behavior of deep beams, numerical Finite Element models using Abaqus software were created. The present test results were compared to those predicted using the Finite Element models. This investigation shows that web reinforcement is quite important for FRP-RC deep beams to achieve a robust behaviour by enhancing its capacity and deformability.

The galvanic corrosion of oil and gas production string is related to wellbore integrity and production safety. In order to study the galvanic corrosion of an oil and gas well tubing assembly and maintain production safety, this paper studied the galvanic corrosion behavior between 13Cr alloy steel tubing and the downhole tools of 9Cr and P110 in formate annular fluid via experimental and numerical simulation methods. The chemical composition, HTHP corrosion tests and electrochemical measurement of the three materials were investigated to analyze the corrosion mechanism and electrochemical parameters. Then, a full-sized 3D galvanic corrosion model of 13Cr tubing and a 9Cr/P110 joint combination was established using COMSOL Multiphysics software based on the electrochemical test results. The mechanism and current variation law of the galvanic corrosion of different tubing materials are discussed and analyzed in the paper. The results revealed that the corrosion rates obtained based on the electrochemical test are as follows: P110 (0.072 mm/y) > 9Cr (0.033 mm/y) > 13Cr (0.0022 mm/y). The current densities of a combination of 13Cr tubing with a 9Cr joint and 13Cr tubing with a P110 joint vary dramatically: the current density of the 13Cr tubing–P110 joint reach 1.6 × 10−4 A/cm2, higher than the current density of the combination of 13Cr tubing and a 9Cr joint. The results of a 3D FEM analysis show that the 13Cr tube demonstrates obvious galvanic corrosion with 9Cr and P110 joints, which is consistent with the analysis results of the polarization curve. This study therefore explains the galvanic corrosion mechanism of different tubing materials and provides guidance for the safe use of tubing in the productive process.

Behind armor blunt trauma (BABT) refers to non-penetrating injuries incurred when body armor deforms into the body of the wearer in the action of stopping a projectile. BABT is relevant in both the military and civilian security populations, and ranges in severity from mild skin laceration to death due to cardiac or pulmonary complications. Considering pulmonary contusion (PC), or bruising in the lungs due to trauma, is estimated to occur in up to 75% of cases of blunt thoracic trauma, PC is estimated to be a major complication in events of BABT. PC is diagnosable by radiological scans, and severity is determined through the percentage of portions containing blood throughout the whole lung. It is estimated that up to 20% of PC injuries are undiagnosed, and severity of PC is often underdiagnosed. Paired with a morbidity rate of up to 82% and an increased likelihood of intubation and ventilation, PC causes a large threat to military and civilian personnel experiencing BABT without reliable access to medical care. This necessitates a predictive measure of PC so that injuries due to BABT may be better mitigated to improve military readiness and expedite return to duty. The main objective of this study is to create a model for lung tissue that includes a damage threshold, and then utilize the model to predict volume of PC in the case of BABT. This starts with the development of a validated material model for lung. Small sample shear testing of porcine lung parenchyma is performed and then fit to a constitutive model derived for shear loading. The fitted parameters are implemented into a finite element material model for lung, and the model is validated by matching kinematic response to experimentally performed indentation testing on lung tissue. Once the material model for lung is achieved, it is included into a human body model that has been validated for use in BABT loading events. Through experimental testing in shear, a failure threshold for lung tissue is determined and included within the human body model so that lung damage resulting from BABT can be output from simulations. With an output of lung damage volume resulting from lung tissue failure, methods are determined for predicting the physiological injury of PC. This is done by correlating the damage volume output from the model to reports of PC volume from live-porcine BABT testing found in the literature. As a result, PC volume can be determined directly from BABT simulations with the human body model, eliminating the need for costly experimental testing on human surrogates. The major contribution of this study towards the protection of first responders and warfighters is the ability to predict PC injury in BABT events. This will help in the diagnosis and mitigation of blunt pulmonary trauma in relation to wearers of body armor.

Biodegradable polymers find applications in many market segments. The ability to meet mechanical requirements within a certain time range, after which it degrades and is naturally absorbed, can be used to produce short-term use products that can be easily disposable with less environmental impact. In the segment of medical devices used in regenerative medicine, these materials are used to produce temporary implants that are naturally assimilated by the human body, avoiding a removal surgery. However, the design of these temporary devices still presents great challenges, namely in the verification of the main requirement: the lifetime of the device, associated with the progressive loss of mechanical properties, until its complete erosion and assimilation. Thus, in this study, a numerical approach is proposed to simulate the polymeric device’s mechanical behavior during its hydrolytic degradation by combining the hydrolysis kinetics, that depends on mechanical factors and promotes a decrease of molecular weight and consequent decrease of mechanical performance, and erosion, when molecular weight reaches a threshold value and the polymer becomes soluble and diffuses outward, resulting in mass loss and decreasing cross-sectional area, which also contributes to the mechanical performance reduction of the device. A phenomenological approach, using the combination of continuum-based hydrolytic damage for the evolution of mechanical properties that depends on the stress field and further removal of the degraded element (to simulate mass loss) was used. Both elastoplastic and hyperelastic constitutive models were applied on this study, where the material model parameters locally depend on the molecular weight.

The realization of the global “Double carbon” target is closely related to the energy-saving travel of human beings. Along with the increase in the number of new energy vehicles around the world, the number of new energy vehicle charging post carports has also increased. However, the collapse of the carport of the new energy vehicle charging post often occurs. The search for ways to optimize the carport structure construction and build a lighter and more stable charging post carport structure has become one of the hot spots in the new energy vehicle industry. Dragonfly wings have a comprehensive evolution in structure, form and function, and their stiffness, stability and resistance to deformation may be a potential solution to optimize the structure of the shed roof. Inspired by this, the study designs two new energy vehicle charging pile canopies based on the dragonfly wing mesh structure to enhance the loading capacity and structural stability of the canopies. The study firstly concludes that the dragonfly wing mesh can enhance the stiffness through experimental analysis, and simulates and models the structure based on the quadrilateral mesh wrinkling and hexagonal mesh arching in its mesh morphology, combined with the national design standard of the charging pile canopy. Studies on the numerical design experiment of the new energy vehicle charging station canopy model based on finite element software under different natural loads, the deflection of shed under the action of self-weight and the deflection, tensile stress and compressive stress under external load are analyzed, and the results show that: (1) The grid structure of the dragonfly wing bionic charging pile shed can optimize the stiffness of the car charging pile shed. (2) According to the wing structure, the test results of the shed roof structure under different working conditions are better than the national standard. (3) Compared with the vertical load, the transverse load of the arched membrane structure, which is represented by the charging pile shed of the new energy vehicle, is larger. (4) According to the stress point of the shed, the structure constraint of the shed can effectively reduce the pressure on the and share part of the load, which can enhance the stability of the shed. (5) In comparison with the displacement of common carport types, the bionic carport shows superior stability and durability. The new bionic carport structure proposed by the research, with stronger pressure bearing, smaller force deformation and lighter weight, is a kind of membrane structure for stable new energy vehicle charging pile carports, which will help further the optimization and promotion of the new energy vehicle industry.

Muscle contraction is a complex phenomenon that begins with chemical processes, continues physiologically, and leads to the production of force. Although the production of force in the muscles depends on factors such as temperature, age, gender, race, but the most important factor is the external load applied to the muscle. Determining the effects of increased load on muscle mechanics is of particular importance for planning exercise activities and rehabilitation processes. In this study, the effects of different external forces on the stress and pressure behavior of the muscle were examined on a simplified model of the biceps. Accordingly, a finite element model of the biceps brachii muscle fiber was constructed. The application of different static loads (2.5 – 100 N) on both the proximal tendon (one-directional) and the proximal and distal tendon (bidirectional) together were investigated. According to the results, it was found that the external force applied in both directions causes a significant increase in displacement behavior and stress.

This study presents a method for finite element (FE) simulation of a deep drawing process of a cold-rolled carbon steel (SPCC) sheet material based on the graphical method. First, uniaxial tensile specimens were prepared and experimental tests were conducted to determine the flow stress curves. The calculation of the fracture points at special strain modes (plane strain, uniaxial tensile strain, and biaxial tensile strain) was presented using the modified maximum force criterion (MMFC). After that, the graphical method was adopted for the estimation of the forming limit curve (FLC) based on several hardening laws. FE models for a deep drawing process of the SPCC sheet were then built using the calculated FLCs. Using FE simulations, the fracture heights of cylinder cups formed by the deep drawing process were finally determined and compared with those from experiments. The results showed a good agreement between simulated and measured fracture height with a maximum of 3.6 % deviation. Additionally, simulations and corresponding experiments were performed to investigate the effects of the blank holder force, punch corner radius, and drawing ratio on the fracture height of cylinder cups.

In recent decades due to the emerging use of composites, earlier metallic vessels have moved to composite overwrapped design. Even though the weight reduction is possible over earlier metallic vessels, various factors such as fluid-wall interaction, failure modes and effect of winding pattern in composite overwrapped pressure vessels need to be very seriously considered for getting a successful design. This paper provides a detailed review on various works carried by the researchers to evaluate the performance of composite overwrapped pressure vessels under various design and environmental factors. These variables include the geometry factors (size & shape of dome, length of cylindrical section), design factors (winding angle, winding thickness, thickness of the liner & overwrap, materials for liner & overwrap, interviewing), defects (notches, flaws), loading conditions (internal & external pressure, axial load, torsion, impact, fatigue, vibration) and the performance parameters (burst pressure, fatigue life, failure modes, leaks, deformations).

In this paper, a SUS304/P92 dissimilar metal butt-welded joint was fabricated, and the welding-induced sensitization of SUS304 austenitic stainless steel in this joint was investigated via the numerical simulation and experiment. In the proposed new numerical model, the time–temperature-precipitation diagram and the time–temperature-sensitization diagram were used to simulate the region and the degree of sensitization, respectively. The predicted degree of sensitization (DOS) in the weld decay zone matched the electrochemical measurements well. Based on the simulation results, the evolution of DOS at the austenitic stainless steel side during the multi-pass welding process was examined in detail. The obtained results can help evaluate the material susceptibility to stress corrosion cracking in austenitic stainless steel joints.

The seismic retrofitting of existing multi-storey multi-bay reinforced concrete (RC) frame buildings by the conversion of selected bays into new RC infilled walls is the subject of this research work. The contribution of dowels that connect a new RC infill wall to the surrounding existing RC frame members was studied through a parametric study. The parametric study was performed by nonlinear response-history analyses of a finite element (FE) model. A two-dimensional (2D) frame was modeled, and analyses were performed to calibrate it using the experimental results obtained from a full-scale experiment. The description of the experiment, the experimental results, and the FE model simulation of the test specimen are presented in Georgiou et al. (2018), Georgiou et al. (2022) and Kyriakides et al. (2015) along with a comparison between the experimental results and the numerical ones. Based on the experimental results it was concluded that the number of dowels used in the experiment resulted in a monolithic behavior of the RC infilled frame. To complement the experimental results and to study the interaction between RC infills and the bounding frame both at the global and local level, a parametric study was performed by reducing the number of dowels starting from a spacing of 100 mm (monolithic) to no dowels. The numerical results of the parametric study show that the number of dowels used in the experimental study can be reduced significantly making the use of this method more attractive. These results also provide a basis for the development of a general model for the design of RC infills in existing RC frames, particularly regarding the connection details of the new RC infill walls to the existing bounding frame. The parametric study of the number of dowels connecting the wall to the bounding frame is presented and conclusions are drawn regarding, among others, the effect on the stiffness of the frame, the top storey displacement, the base shear, the axial and shear forces in the dowels, as well as the bending moment at the base of the wall and the outer columns. Some observations that can lead to design recommendations are also presented.

Although it is evident that the RC infill wall is an economic and practical way to improve the lateral strength of framed structures and a retrofitting method for existing buildings to withstand earthquake loads, there are still a lot of limitations regarding their application. Codes do not provide any guidance for their design and detailing or specific regulations for their interaction with the bounding frame. Furthermore, specific directions do not exist for the modelling or evaluation of frame bays converted into RC walls, depending on the type and details of the connection. A representation of the real behaviour of the wall and its interaction with the bounding frame during an earthquake is necessary to provide more accurate guiding information. For this aim, numerical models of this structural system were developed and are presented in this paper. The experimental results of the project SERFIN, which was a full-scale four-storey model tested with the pseudo-dynamic method at the ELSA facility of the Joint Research Centre in Ispra, were used to calibrate the numerical models. Two-dimensional (2D) frames were modelled in DIANA FEA, and nonlinear transient analyses were performed to simulate the experimental results obtained from the SERFIN full-scale experiment. In this paper, the FE model simulation of the test specimen is presented along with a comparison between the experimental results and the numerical ones. It was concluded that the developed numerical models capture effectively the behaviour of the studied structural system and can be used for parametric studies to examine the effects of the number of dowels on the behaviour of the system and propose design guidelines based on the results of the parametric study.

In this study, vibration control of rectangular plates with piezoelectric (PZT) structures under different loading conditions is considered. By using different materials on the plate, the effect of material properties on vibration control and its connection with piezoelectric structures are investigated. The PZT patches are placed in the certain areas of the plate. The strains are greatest in these regions, and these strains are derived from the modes and natural frequencies of the plate. The optimum thicknesses of these patches are determined from the material and geometric properties of the plate and the material properties of the piezoelectric patches. It is found that the thickness of the piezoelectric patches must change as the material of the plate changes. It is observed that the applied voltage values vary according to the location of the patches. In addition, it has been seen that the damping parameter has different effects on the response of the system under different loads.

As a novel metal forming process, cross-wedge rolling (CWR) is widely used in the manufacture of large axles in the rail transportation industry. When the forming process of the axle is studied, its formability becomes one of the key issues in the metal forming process. This paper takes LZ50 axle steel as the research object. Through the application of ANSYS finite element simulation software, combined with previous research and literature, a dynamic simulation of the rolling process is carried out, and the stress, strain and temperature field of the axle steel in the forming process are analysed. The results show that with the deepening of rolling, the plastic deformation of the metal becomes increasingly obvious. When the finishing section is reached, the temperature on the surface and inside the rolled piece reaches relatively uniform distribution.

Brushless doubly fed reluctance generator (BDFRG) provides a good substitute for the doubly fed induction generator for the wind energy applications due to the nonexistence of the slip rings. Real time modelling of the BDFRG is a challenge due to the high leakage inductance of the stator windings. While the magnetic saturation of the iron parts affects the inductances values, therefore studying the effect of magnetic saturation on the BDFRG performance is important. In this paper, a BDFRG model including iron saturation is built. The finite element (FE) analysis using FEMM software is used to generate the relationship between the generator currents and the inductances, the generated data are recorded in a lookup table. A Simulink model of the BDFRG driven wind turbine, with two cases of constant and variable inductances, are developed and verified with FE analyses at range of wind speeds above and below the synchronous speed. The lookup table proposes is verified using finite element analysis at different modes of operation of wind speed and compared with the constant inductance model to show the importance of saturation inclusion in the generator model for accurate generator modelling representation.

Nonlinear unloading plays an important role in predicting springback during plastic forming process. To improve the accuracy of springback prediction which could provide a guide for precision forming, uniaxial tensile tests and uniaxial loading–unloading–loading tensile tests on SUS304 stainless steel were carried out. The flow stress mathematical model and chord modulus mathematical model were calibrated according to the test results. A constant elastic modulus three-point bending finite element model (E0FEMB) and a constant elastic modulus roll forming finite element model (E0FEMR) were established in MSC.MARC. The chord modulus was output by the PLOTV subroutine to determine the mean modulus of different regions, and the mean modulus three-point bending finite element model (E¯cFEMB) and the mean modulus roll forming finite element model (E¯cFEMR) were defined. The constant modulus finite element model (E0FEM) simulation results and the mean modulus finite element model (E¯cFEM) simulation results were compared with the three-point bending tests and roll forming tests test results. The difference between the simulation results and the test results was small, indicating that the mean modulus was feasible to predict the springback, which verified the suitability of the E¯cFEM.

The generation of a topographical surface or digital elevation model for a given set of points in space is a known problem in civil engineering and topography. In this article, we propose a simple and efficient way to obtain the terrain surface by using a structural shell finite element model, giving advice on how to implement it. The proposed methodology does not need a large number of points to define the terrain, so it is especially suitable to be used with data provided by manual topographical tools. Several examples are developed to demonstrate the easiness and accuracy of the methodology. The digital terrain model of a real landscape is modeled by using different numbers of points (from 49 to 400) using a regular mesh or a randomly generated cloud of points. The results are compared, showing how the proposed methodology creates a sufficiently accurate model, even with a low number of points (compared with the thousands of points handled in a LiDAR representation). A real case application is also shown. As an appendix, the sample code to generate the examples is provided.

To optimize the segment storage and hoisting plan of precast segmental composite box girders with corrugated steel web bridges, China’s first precast segmental composite girder bridge with corrugated steel webs is taken as the background. The difference between the precast segmental composite box girders with corrugated steel webs and the traditional concrete box girder is proven by numerical simulation. The stress and deformation characteristics of the segmental girder during storage and hoisting are analysed, and reasonable control measures are proposed. The data suggested that compared with ordinary concrete box girders, the smaller torsional stiffness and lateral stiffness of the precast segmental composite box girder with corrugated steel web segments lead to larger roof stress and deformation during the storage and hoisting periods. The number of storage layers of segmental girders should not exceed two, and the four hoisting point scheme should be adopted for hoisting. It is recommended to set one to two channel steel supports of no less than 20 grade steel between the top and bottom plates to avoid excessive deformation of the roof. With the increase in the segment length, the roof deformation and stress increased regardless of the storage period and the hoisting period. If the safety factor needs to be increased, when the segment length is short (1.6 m–3.2 m), increasing the support size is recommended. When the segment length is longer (4.0 m, 4.8 m), increasing the number of supports is recommended.

Composite sandwich structures are well-suited for applications requiring high bending strength, flexural rigidity, crashworthiness, and light weight. However, skin–core debonding and core failure remain a barrier to optimal structural performance when polymeric foams are used as core materials. Suppressing or compartmentalising these failure modes can enhance the structural integrity of sandwich structures. In this paper, the flexural response of a sandwich structure was improved by adding carbon fibre-reinforced plastic in the form of through-thickness ribs during the manufacturing process. The effect of the position of the ribs was investigated using a quasi-static three-point bend test. A camera was used to capture failure events, while the digital image correlation technique provided the full-strain field at different stages of loading. Improved flexural performance was obtained when a reinforcement was placed on either side of the loading roller. With this configuration, skin–core debonding was restricted to a confined portion of the panel, resulting in a more localised and stable fracture process, which involved enhanced foam crushing and hardening. A simple FEA approach has been adopted in this paper and has proven to be an effective approach for capturing the details of the failure process, including the debonding in the composite foam structures, without the need for complex and computationally expensive interface modelling.

Peer reviewed: True, Over time, high-temperature superconductor (HTS)-coated conductors (CCs) have proven to be promising candidates for future high-efficiency and high-power density electrical machines. However, their commercialization is handicapped due to the AC dissipative loss that occurs upon exposure to external magnetic fields. In rotating electromagnetic devices, the external magnetic field is a combination of alternating and rotating magnetic fields. Most of the research is devoted to the effect of exposure of the superconductors to alternating magnetic fields only. This article presents an investigation to observe the behavior of HTSCCs under rotating magnetic fields, particularly the AC loss, using a finite-element-based homogeneous H-formulation technique. Our investigation shows that the AC loss could be considerably high when HTSCCs are exposed to rotating magnetic fields and, ultimately, could affect the cooling efficiency of future high-efficiency and high-power density electrical machines.

Terahertz scattering-scanning near-field optical microscopy (THz s-SNOM), combining the best features of terahertz technology and s-SNOM technology, has shown unique advantages in various applications. Consequently, building a model to characterize near-field interactions and investigate practical issues has become a popular topic in THz s-SNOM research. In this study, a finite element model (FEM) is proposed to quantify the near-field interactions, and to investigate the edge effect and antenna effect in THz s-SNOM. Our results indicate that the proposed model can give us a better understanding of the near-field interactions and direct the parameter design of the probe for THz s-SNOM.

To rigorously evaluate the health of a steel bridge subjected to vehicle-induced fatigue, both a detailed numerical model and effective fatigue analysis methods are needed. In this paper, the process for establishing the structural health monitoring (SHM)-oriented finite element (FE) model and assessing the vehicle-induced fatigue damage is presented for a large, specially shaped steel arch bridge. First, the bridge is meticulously modeled using multiple FEs to facilitate the exploration of the local structural behavior. Second, manual tuning and model updating are conducted according to the modal parameters measured at the bridge’s location. Since the numerical model comprises a large number of FEs, two surrogate-model-based methods are employed to update the model. Third, the established models are validated by using them to predict the structure’s mode shapes and the actual structural behavior for the case in which the whole bridge is subjected to static vehicle loads. Fourth, using the numerical model, a new fatigue analysis method based on the high-circle fatigue damage accumulation theory is employed to further analyze the vehicle-induced fatigue damage to the bridge. The results indicate that manual tuning and model updating are indispensable for SHM-oriented FE models with erroneous configurations, and one surrogate-model-based model updating method is effective. In addition, it is shown that the fatigue analysis method based on the high-circle fatigue damage accumulation theory is applicable to real-world engineering cases.

Strengthening can increase or recover the bearing capacity of steel constructions of buildings and structures in operation. Besides well-known strengthening techniques, including an increase in the sectional area by means of attaching steel plates, angles, channels, pipes etc. to a strengthened element, other methods, that involve the use of carbon fiber-reinforced composite materials, have strong prospects. So far, the structural behaviour of steel constructions, strengthened with carbon fiber-reinforced composite materials, is understudied, and this fact restrains the practical application of this strengthening method. The article presents the results of complex experimental, theoretical and numerical studies of the features of the operation of steel-stretched elements reinforced with glued carbon fiber. The emphasis is on the load-bearing capacity of the reinforced element, and not on the mechanism of destruction of the glue. This is due to the use of an adhesive joint performed using the glue and gluing technology recommended by the manufacturer of carbon fiber. It has been experimentally established that, in this case, the stresses in carbon fiber cannot exceed a certain value. Theoretical dependences for the calculation of CFRP-reinforced steel stretched elements are proposed. The scientific novelty of this research project is a set of basic principles and methods, developed to identify the bearing capacity of steel rods, strengthened with carbon fiber-reinforced composite materials, taking into account the joint strength performance of a steel rod and adhesively bonded carbon-fiber-reinforced composite material, as well as the new findings thus obtained, such as the theoretical dependencies needed to identify the bearing capacity of steel rods strengthened with carbon-fiber-reinforced composite materials; experimental data on the joint strength performance of carbon-fiber-reinforced composite lamellas attached to a steel rod by an adhesive; experimental data on the performance and the bearing capacity of steel rods strengthened with carbon-fiber-reinforced composite lamellas; development of finite element models of steel rods strengthened with carbon-fiber-reinforced composite materials, and computational studies of steel rods strengthened with carbon fiber-reinforced composite materials.

With the wide application of carbon fiber reinforced polymer (CFRP) plate, used for strengthening existed concrete structures, the prestressing technology of CFRP plate is becoming a hot topic, in order to sufficiently develop its high-strength peculiarity. In this paper, a full-scale hollow-section beam with length of 16 m taken from an old bridge which was in service for about 20 years was first examined for existed cracks and repaired by filling epoxy adhesive, and then the beam was strengthened with prestressed CFRP plates. The CFRP plates were tensioned and fixed with flat-plate anchorages at ends and bonded with adhesive on the bottom surface of the beam. The strengthened beam was experimentally studied using a four-point test to measure the concrete strain along the height of the mid-span section and the mid-span deflection. The finite element model of the strengthened beam was verified by the comparison of test results and used for an extending study of parametric analysis considering the effect of the length and amount of CFRP plates. Results indicated that with an increase in the length and amount of CFRP plates, the mid-span deflection of the beam decreases with the increased cracking resistance and bearing capacity, while the ultimate failure mode transfers from the under-reinforcement to the over-reinforcement.

In order to expand the applications of cold-formed thin-walled steel structures, this study proposes a new type of composite wallboard composed of cold-formed thin-walled C-shaped steel and multi-layer concrete, in which C-shaped steel serves as the skeleton, foam concrete acts as the thermal insulation material, and fine aggregate concrete and cement mortar play the part of envelopes. The composite wallboard can be made in a factory assembly line, meeting the requirements of the building (civil and structural) industry. Two steel-frame composite wallboard shear walls were subjected to reciprocating loading, with the connection mode as the design parameter, to investigate the seismic performance of the structure. The failure mode, hysteresis curve, skeleton curve, strength degradation, stiffness degradation, ductility, and energy dissipation capacity of the specimens were analyzed. On this basis, the finite element (FE) model of the steel-frame composite wallboard was established, and the model’s accuracy was verified by comparing the bearing capacity and the skeleton curve. Results show that the structure shows shear failure characteristics, and the cement mortar layer and the fine aggregate concrete layer are separated from the C-shaped steel after being crushed. The infilled foam concrete is also crushed, and the welding seams between the extended C-shaped steel and steel frame of the WP-1 specimen are damaged. The hysteresis curves of the two specimens have a clear pinch, but the area enclosed by the hysteresis loop is large, and the energy dissipation capacity is also present. The yield load and ultimate load of the WP-2 specimen are higher than those of the WP-1 specimen, indicating that the higher the connection strength between the composite wallboard and the steel frame, the greater the ultimate carrying capacity of the specimen. The established FE model can accurately estimate the seismic performance of steel-frame composite wallboard shear walls.