Arch Structure Research Articles

Effect of additional body weight on arch index and dynamic plantar pressure distribution during walking and gait termination.

The medial longitudinal arch is considered as an essential feature which distinguishes humans from other primates. The longitudinal arch plays a supporting and buffering role in human daily physical activities. However, bad movement patterns could lead to deformation of arch morphology, resulting in foot injuries. The authors aimed to investigate any alterations in static and dynamic arch index following different weight bearings. A further aim was to analyze any changes in plantar pressure distribution characteristics on gait during walking and stopping, Twelve males were required to complete foot morphology scans and three types of gait tests with 0%, 10%, 20% and 30% of additional body weight. The dynamic gait tests included walking, planned and unplanned gait termination. Foot morphology details and plantar pressure data were collected from subjects using the Easy-Foot-Scan and Footscan pressure platform. No significant differences were observed in static arch index when adding low levels of additional body weight (10%). There were no significant changes observed in dynamic arch index when loads were added in the range of 20% to 30%, except in unplanned gait termination. Significant maximal pressure increases were observed in the rearfoot during walking and in both the forefoot and rearfoot during planned gait termination. In addition, significant maximum pressure increases were shown in the lateral forefoot and midfoot during unplanned gait termination when weight was increased. Findings from the study indicated that excessive weight bearing could lead to a collapse of the arch structure and, therefore, increases in plantar loading. This may result in foot injuries, especially during unplanned gait termination.

A Lagrangian Hencky-type non-linear model suitable for metamaterials design of shearable and extensible slender deformable bodies alternative to Timoshenko theory

Among the most studied models in mathematical physics, Timoshenko beam is outstanding for its importance in technological applications. Therefore it has been extensively studied and many discretizations have been proposed to allow its use in the most disparate contexts. However, it seems to us that available discretization schemes present some drawbacks when considering large deformation regimes. We believe these drawbacks to be mainly related to the fact that they are formulated without keeping in mind the mechanical phenomena for describing which Timoshenko continuum model has been proposed. Therefore, aiming to analyze the deformation of complex plane frames and arches in elastic large displacements and deformation regimes, a novel intrinsically discrete Lagrangian model is here introduced whose phenomenological application range is similar to that for which Timoshenko beam has been conceived. While being largely inspired by the ideas outlined by Hencky in his renowned doctoral dissertation, the presented approach overcomes some specific limitations concerning the stretch and shear deformation effects. The proposed model is applied to get the solutions for some relevant benchmark tests, both in the case of arch and frame structures. It is proved that, also when shear deformation effects are of relevance, the enriched, yet simple, model and numerical computation scheme herein proposed can be profitably used for efficient structural analyses of non-linear mechanical systems in rather nonstandard situations.

Increased effective piezoelectric response of structurally modulated P(VDF-TrFE) film devices for effective energy harvesters

The low piezoelectric response (piezoelectric coefficient d33 lower than 30 pC N−1) of PVDF-based polymers limits their practical applications. Here we report a mechanical structure which can enhance the effective piezoelectric response of P(VDF-TrFE) copolymer. The polymer films were fabricated into a circular arch structure or arrays of arch structures. When a plane force was applied to the arch films, the force is concentrated at the outer rim of the arch structure. The effective piezoelectric response can be enhanced by >70 times because of the stress concentration and the measured effective piezoelectric response can be as high as 1990 pC N−1. The arch films exhibit an enhanced energy harvesting performance when they are utilized as mechanical energy harvesting devices. The output power density was improved by >2700 times compared with that measured in the films without arch structure. An output power density of 9 mW cm−3 was achieved in the arch films under non-resonance frequency. These results indicate that the proposed polymer-based structure is promising for the practical applications in high-performance flexible piezoelectric devices.

A Study on the Strength and Fatigue Properties of Seven-Wire Strands in Hangers under Lateral Bending

Hangers are important tensile members in half-through arch bridges and through arch bridges (HTABs and TABs). The floating deck structures of HTABs and TABs will commonly produce longitudinal deformation and rotate under the effect of temperature and the temperature gradient, which will cause bending deformation at anchorages of fixed-end hangers. This bending deformation can generate adverse bending stress for hangers and decrease the strength and fatigue properties of the seven-wire strands in the hangers. Firstly, theoretical derivation and finite element analysis are conducted to study the bending stress of hangers that is caused by bending deformation. We find that bending stress of hangers is mainly generated by lateral bending caused by the difference in longitudinal displacement at both ends of the hangers under the effect of temperature. Subsequently, the ultimate tensile strength of the seven-wire strands under lateral bending is obtained by FEM and an experimental study. The ultimate tensile strength of the seven-wire strands could decrease by 23.3% when lateral bending is considered. Moreover, the relationship between the fatigue properties of the seven-wire strands and lateral bending is obtained based on observing the ultimate tensile strength under lateral bending. Lateral bending significantly influences the fatigue properties of the seven-wire strands. When the lateral bending angle reaches about 50 mrad, the fatigue resistance of the seven-wire strands drop by almost 40%. The considerable decrease in the strength and fatigue properties of the seven-wire strands indicates that lateral bending has a significant adverse influence on hangers that consist of seven-wire strands. Finally, it is advised to use the tied arch structure for HTABs and TABs to mitigate the adverse influence of lateral bending on hangers.

Spatiotemporal remodeling of embryonic aortic arch: stress distribution, microstructure, and vascular growth in silico.

The microstructure for mature vessels has been investigated in detail, while there is limited information about the embryonic stages, in spite of their importance in the prognosis of congenital heart defects. It is hypothesized that the embryonic vasculature represents a disorganized but dynamic soft tissue, which rapidly evolves toward a specialized multi-cellular vascular structure under mechanical loading. Here the microstructural evolution process of the embryonic pharyngeal aortic arch structure was simulated using an in ovo validated long-term growth and remodeling computational model, implemented as an in-house FEBio plug-in. Optical coherence tomography-guided servo-null pressure measurements are assignedas boundary conditions through the critical embryonic stages. The accumulation of key microstructural constituents was recorded through zoom confocal microscopy for all six embryonic arch arteriessimultaneously. The total amount and the radial variation slope of the collagen along the arch wall thickness in different archtypes and for different embryonic times, with different dimension scales, were normalized and compared statistically. The arch growth model shows that the stress levels around the lumen boundary increase from [Formula: see text] (Stage 18) to a level higher than [Formula: see text] (Stage 24), depending on matrix constituent production rates, while the homeostatic strain level is kept constant. The statistical tests show that although the total collagen levels differentiate among bilateral positions of the same arch, the shape coefficient of the matrix microstructural gradient changes with embryonic time, proving radial localization, in accordance with numerical model results. In vivo cell number (DAPI) and vascular endothelial growth factor distributions followed similar trends.

Investigation of arch structure of granular assembly in the trapdoor test using digital RGB photoelastic analysis

The aim of this study was to investigate the arching phenomenon in granular assembly. A series of two-dimensional trapdoor tests were conducted using model particles coated with a thin photoelastic sheet. Digital photo images of the model particle assembly were continuously taken during the tests, and the force of each model particle was quantitatively evaluated using a digital RGB photoelastic analysis. The test results showed that two arch structures were initially generated with trapdoor yielding, and the inner arch gradually expanded to the outer arch, while the outer arch became more solid. Given that the force per particle in the arch structure did not change significantly during the arch formation process, we concluded that the arch formation process progressed through the transmission of the force chains rather than by a change in the magnitude of the particle force.

New Moray Eel Species of Strophidon genus (Muraenidae) from Vietnam

A new species, Strophidon dawydoffi sp. n., from Nha Trang Bay (South China Sea, Vietnam) was described. The new species is well distinguished from the cooccurring S. sathete species by a thinner and elongated body, tail lobiform-extended at the end, external absence of vertical fins, a much smaller number of preanal vertebrae, elongated vertebral centra in the middle portion of the caudal region of the vertebral column, the structure of neural arches and parapophyses, variegated coloring of the body and oral cavity, a larger number of teeth in the inner rows on maxillare and dentale, and two or three rows of papillae on the lips. Differences in the number of infraorbital pores and in the shape of the snout between S. sathete specimens are associated with individual variability.

Analysis of Influence of Different Parameters on Structural Stability of Beam String Beam

The string beam structure is a new type of space structure, which satisfies the requirements of buildings for large spans, has good application value and broad application prospects. In this paper, the influence of the three-parameter ratio of the span, the prestress value and the number of strut on the stability of the beam string is studied. The modeling of the string member is carried out by SAP2000 software. The simulation results show that the arch structure of the stringed beam has the best stability when the span ratio is 0.25. When appropriate prestressing is applied to the structural cable, the stability of the structure will be significantly improved. The number of struts is not as good as possible. Considering the influence of the struts on the structure, choose the right amount.

The effect of rise-span ratio on the rigid-framed arch bridges

The rigid-framed arch structure is a popular bridge structure on medium and small span bridge such as flyover. Rise-span ratio affects the rigid-framed arch structure performance, in order to analyse the influence on the rigid-framed arch structure of different rise-span ratio, a calculation model of the rigid-framed arch structure on the basis of the project established using the large general finite element software, by adjusting the rise value to change the rise-span ratio, analysing and comparing the structural internal force and deformation condition of the rigid-framed arch in different rise-span ratio under the action of constant live load, temperature change, and foundation settlement. The influence of different rise-span ratio on the rigid-framed arch stress summarized.

The Influence of Gender, Age, and Body Mass Index on Arch Height and Arch Stiffness

Arch structure and arch function play an important role in maintaining balance, bearing body weight, and absorbing ground reaction forces. However, arch structure and arch function are known to vary extensively and may be affected by factors such as gender, age, and obesity. Therefore, the purpose of this study was to examine the influence of gender, age, and body mass index (BMI) on arch height and arch stiffness. A total of 173 participants (aged 57.60 ± 11.19 years, mean BMI 25.12 ± 3.93 kg/m2) participated in this cross-sectional study. A 3-dimensional laser scanner was used to measure foot structure information in each subject, from which arch height and arch stiffness were calculated. The results showed that women had low-arched feet compared with men (p = .001), and no arch stiffness difference was found. Older individuals tended to have a stiffer arch than middle-aged and younger individuals (p < .05), and no arch height difference was found. BMI had an impact on arch height (p < .05) but not arch stiffness. Finally, a weak positive relationship existed between arch height and arch stiffness (r = 0.32, p < .01). The findings suggest that gender, age, and obesity have a certain impact on arch structure and arch stiffness. Figuring out the relationship between these factors and arch structure may be helpful in understanding the bases of foot deformity and foot dysfunction.

Experimental research into the response of segmental barrel vaults to repetitive static and dynamic loads

The article briefly recalls the issue of historical buildings located in seismically active areas. In the introduction of the paper, the issue of the change of the dynamic response of the structure as a method for determining the possible damage of the structure, which can be difficult to detect by other diagnostic procedures, is discussed. Furthermore, the article outlines the procedure for determining some significant characteristics (such as bending stiffness etc.) by means of the dynamic response of the structure, and simplified relationships and recommendations for diagnosing arch structures based on its dynamic response. The focus of the paper is on the general analysis of the results of experimental tests of five segmental barrel vaults, of which two were reinforced with CFRP strips subjected to alternating static and dynamic loads. Due to the structure of the vault - single-layer masonry with a thickness of 150 mm - a loading mode was required. In the article conclusion the test results are interpreted with regard to the above mentioned facts (extent of experimental loading, specific vault structure) and it is stated that they have demonstrated the possibility of using a change of dynamic characteristics as a possible diagnostic method of the origin and development of defects on the vault structure

Parallel computing modes of multiobjective game

SummaryFor the design of multiobjective optimum decision, three methods based on parallel computing and game theory were raised to transfer the multiobjective design into the decision. Then, the multiobjective optimum design problems of numerical calculation examples, compensative sheave block, and antiseismic design of arch structures can be solved. Three parallel computing modes (ie, I, II, and III) were designed correspondingly. First, parallel mode I can make the game process visually intuitive with the disadvantage that the computing load cannot be balanced. Second, parallel mode II can better solve the imbalance of computing load between different objectives, obtain good parallel speedup and host efficiency. Furthermore, parallel mode III has the advantages of the above two parallel modes. However, its disadvantage is that data exchange between computing units is frequent, and this results in an increase in communication time. The simulation results suggest that all the parallel game algorithms can give considerations to multiple objectives, improve the seeking efficiency and make the solutions more robust.

Predicting the wet collapse pressure for flexible risers with initial ovalization and gap: An analytical solution

As offshore hydrocarbon production moves towards ultra-deep water, flexible risers have to withstand the huge hydro-static pressure without collapse. They are designed with strong collapse capacities, allowing them to operate under the condition where their annuli are flooded by the seawater. However, initial imperfections can weaken the collapse capacity under such a flooded condition, triggering the so-called “wet collapse”. Two common initial imperfections, the carcass ovality and the radial gap between the carcass and pressure armor, would reduce the collapse strength of flexible risers significantly. Mostly, collapse analyses are performed through numerical simulations, which are less feasible for the design stage of flexible risers comparing with analytical models. To date, there are few analytical models available in public literature to predict the wet collapse pressure of flexible risers accounting for initial ovality and gap. To meet this demand, an analytical model is established in this paper to address these issues. This model is developed as a spring-supported arch, solving the collapse pressure with stability theories of ring and arched structures. This analytical model is verified by numerical simulations, which gives prediction results that correlate well with the numerical ones.

Integrated cutting force measurement system based on MEMS sensor for monitoring milling process

In manufacturing process, the stability of cutting state is especially important for processing quality. Monitoring cutting force is a research hotspot for a long time. In this paper, an integrated cutting force measurement system based on piezoresistive MEMS sensor for measuring axial force and torque in milling process is proposed. Based on the thin-walled cylinder and the arch structure, the stress-transforming element of composite splitted structure of conical and cylindrical shell is developed to detect cutting force. The natural frequency of the proposed element has a great improvement in strain sensing sensitivity that can satisfy most cutting situations. A piezoresistive MEMS sensor designed as sensitive component and used in the cutting force measurement system. When the elastic body was sustained cutting force, the piezoresistive MEMS sensors that arranged on the element sense the deformation and output voltage signals to reveal the change of cutting force. In order to verify the basic performance of the cutting force measurement system, static calibration and modal impact tests are carried out. The results indicate that the sensor’s original sensitivity is 2.85 × 10−2 mV/N and 2.90 mV/Nm in axial and torsional directions. Dynamic cutting tests show that the cutting force measurement system can reflect the variation of cutting status very well. It is qualified to monitor the change of axial and torsional forces in practical applications. The cutting test results indicate the measurement system scarcely reduce the workpiece surface quality in machining process.

Effects of embedded trench installations using expanded polystyrene geofoam applied to buried corrugated steel arch structures

Over the years, considerable progress have been made for the improvement of the design criteria of buried culverts that increased in size and numbers with the development of information and technology in this field. This research investigates the effects of trench installation methods with expanded polystyrene (EPS) geofoam on the behavior of buried corrugated steel arch structure. A finite element analysis program, ABAQUS, was used to model and analyze the structure. For this study, an S275 corrugated steel with profiles of 152 × 51mm and 400 × 150mm, and thickness ranging from 3 mm to 7 mm was used. The structure was analyzed for three different configurations, namely; initial (without EPS geofoam), imperfect trench installation (ITI), and embedded trench installation (ETI) through three parametric analysis considering the influence of EPS geofoam’s geometry, thickness and corrugation profile of steel. The results from the finite element analyses revealed that ETI models reduced the earth pressure, deflection, and stress at the crown by 68%, 40%, and 39% on the average. It is recommended to conduct further study regarding ETI to validate the results and to further improved the design criteria of buried corrugated steel arch as it is expected to bring about cost reduction and stability for buried structures.

Adult rigid flatfoot

To analyze the efficacy of arthrodesis combined with osteotomy applied to subtalar, calcaneocuboid, and talonavicular joints for the treatment of adult rigid flatfoot.This retrospective study included 29 adult patients with rigid flatfoot who underwent triple arthrodesis combined with osteotomy from January 2015 to December 2017. All patients suffered from stage III of adult acquired flatfoot. Patients returned for a clinical and radiologic follow-up evaluation at an average of 19.5 (range, 15-27) months postoperatively. Outcomes were assessed by comparing pre- and postoperative AOFAS scores, VAS pain scores, and Karlsson scores, and the radiographic assessment including Meary, Pitch, and Kite angles.Twenty six patients returned for final evaluation. Twenty four patients had an excellent or good outcome on patient subjective self-assessment. All the VAS scores, AOFAS scores, and Karlsson scores at final follow-up showed different extents of improvement. The mean Meary angle significantly decreased from 25.8 ± 5.4 degrees preoperatively to 6.9 ± 7.7 degrees at final follow-up, and the mean Pitch angle improved markedly from 12.5 ± 3.7 points preoperatively to 23.2 ± 4.1 points at final follow-up (P < .001).Arthrodesis combined with osteotomy can effectively correct calcaneal valgus deformity, restore arch structure, and relieve foot pain in adult rigid flatfoot.

Simulation and Result Analysis of Bridge Backfilling Process Based on ANSYS

The covered bridge of corrugated steel has many advantages, one of which has good adaptability to deformation. It should be noted that as a flexible arch structure, it is necessary to pay attention to the backfilling and expansion scheme. According to the available data, it is clear that modern researchers conduct analysis and research on experimental models and actual projects, and test the deformation and internal forces of the bridge and culvert structure of the backfilling project, but there is no impact on the backfill construction structure. Mechanics factors are studied and analyzed. In order to make up for this gap, this paper uses finite element software to build the model based on the actual engineering, and then calculates a variety of different backfilling schemes to study the influence of internal force and structural deformation of different backfilling schemes on structural mechanics. Researchers provide relevant references for research.

Exact solution of an integrable anisotropic spin chain model

An integrable anisotropic Heisenberg spin chain with nearest-neighbour couplings, next-nearest-neighbour couplings and scalar chirality terms is constructed. After proving the integrability, we obtain the exact solution of the system. The ground state and the elementary excitations are also studied. It is shown that the spinon excitation of the present model possesses a novel triple arched structure. The elementary excitation is gapless if the anisotropic parameter is real while the elementary excitation has an enhanced gap by the next-nearest-neighbour and chiral three-spin interactions if the anisotropic parameter is imaginary. The method of this paper provides a general way to construct integrable models with next-nearest-neighbour interactions.

The effect of load reduction on underground concrete arch structures in embedded trench installations

This analytical and experimental study examined the effects of using EPS Geofoam to reduce the earth pressure on underground arch structures. The finite element models developed using 2-D and 3-D approaches and nonlinear soil models were calibrated using field testing data. The behavior of the structure was investigated for varying thicknesses of the geofoam layer to determine the optimum level. The results of the finite element analysis revealed a load reduction of more than 80% when using the embedded trench installation (ETI) method. These results were within 10% of the experimentally measured values, demonstrating that the ETI method is an effective way to reduce earth pressure on underground arch structures.

In-plane stability of shallow concrete arches under fire

PurposeConcrete arch structures are commonly constructed for various civil engineering applications. Despite their frequent use, there is a lack of research on the response and performance of concrete arches when subjected to fire loading. Hence, this paper aims to investigate the response and in-plane failure modes of shallow circular concrete arches subjected to mechanical and fire loading.Design/methodology/approachThis study is conducted through the development of a three-dimensional finite element (FE) model in ANSYS. The FE model is verified by comparison to a non-discretisation numerical model derived herein and the reduced modulus buckling theory, both used for the non-linear inelastic analysis of shallow concrete arches subjected to uniformly distributed radial loading and uniform temperature field. Both anti-symmetric and symmetric buckling modes are examined, with analysis of the former requiring geometric imperfection obtained by an eigenvalue buckling analysis.FindingsThe FE results show that anti-symmetric bifurcation buckling is the dominant failure mode in shallow concrete arches under mechanical and fire loading. Additionally, parametric studies are presented which illustrate the influence of various parameters on fire resistance time.Originality/valueFire response of concrete arches has not been reported in the open literature. The authors have previously investigated the stability of shallow concrete arches subjected to mechanical and uniform thermal loading. It was found that temperature greatly reduced the buckling loads of concrete arches. However, this study was limited to the simplifying assumptions made which include elastic material behaviour and uniform temperature loading. The present study provides a realistic insight into the fire response and stability of shallow concrete arches. The findings herein may be adopted in the fire design of shallow concrete arches.