Arch Structure Research Articles

Mass discharge rate of granular flow in eccentric silos with variable side wall friction

There are many studies on the effect of side wall friction on mass discharge rate (MDR), but the physical mechanism is lacking. In this paper, by changing side wall friction of eccentric silos, the relationship between macroscopic MDR and microscopic frictional coefficient was established, and the regulation of MDR up to a range of 40 % was realized. Furthermore, it is revealed that the variation of MDR is caused by the change in geometric structure of free-fall arch (FFA). In addition, the velocity of particles on FFA is the same under different MDR. The reason is that under high frictional coefficient, the gravitational potential energy of particles is more dissipated in the rotational motion caused by resistance. This work explains for the first time the mechanism of the frictional coefficient on MDR, and provides a data reference for improving the theoretical model of MDR.

Dynamic instability and nonlinear response analysis of nanocomposite sandwich arches with viscoelastic cores

This paper presents a comprehensive study of the nonlinear dynamic behavior and snap-through phenomena in sandwich arch structures with viscoelastic cores and carbon nanotube-reinforced nanocomposite face sheets. Subjected to uniform time-dependent pressure shocks, these arches exhibit complex snap-through behavior critical for practical engineering applications. Utilizing third-order shear deformation theory, the study accurately captures nonlinear behaviors. The viscoelastic core, modeled with the Kelvin-Voigt law, enhances damping and reduces vibration amplitudes. Numerical solutions are obtained using a Chebyshev-based Ritz method, Newmark integration, and Newton-Raphson method. The Budiansky-Ruth criterion evaluates dynamic buckling loads. Key findings include significant instability near buckling loads, increased buckling loads and vibration damping due to viscoelastic effects, reduced buckling loads with foam cores, improved performance with CNTs, and more pronounced CNT effects with greater deflections. Additional conclusions highlight the sensitivity of dynamic snap-through to geometric parameters and the superior accuracy of the proposed approach compared to traditional models. This research advances the understanding and design strategies for nonlinear sandwich arch structures, enhancing predictive capabilities in complex structural systems.

Effect of foot type on electromyography characteristics and synergy of lower limb muscles during running

The foot structure is associated with different running mechanics. The central nervous system is responsible for using the muscles through synergies during locomotion. The purpose of the present study was to examine the effect of foot structure on the electromyography factors and the synergy of the selected muscles of the lower extremity. Tibialis anterior, extensor digitorum longus, peroneus longus, soleus, biceps femoris, vastus lateralis, gastrocnemius lateralis and medialis muscles activity of 60 barefoot recreational runners with different foot structures was recorded while running at a speed of 3.3 m/s. Muscle activity was measured in the running cycle. Besides, muscle synergies were extracted using non-negative matrix factorization algorithm. The results showed that there were differences between groups with different foot type in muscle activity under different phases of running in some muscles. Furthermore, the findings indicated that the number of synergies was similar in different groups and the relative weight of muscles was not different across groups. In conclusion, despite the difference in muscle activity under different phases of the running cycle, muscle synergies are similar among the groups. This can indicate similar control by the central nervous system in runners with different arch structures while running and the observed changes in muscle activity can be attributed to the type of forces exerted on the body, the length-tension relationship, and changes in the direction of the lower limbs in people with different arch structures.

Study on the Bearing Structure of Key Strata and the Linkage Evolution Mechanism of Surface Subsidence in Shallow Coal Seam Mining

Shallow coal seam mining results in the formation of various bearing structures in key strata, leading to varying degrees of surface subsidence and severe disruption to the surface ecological environment. To investigate the coupled evolution characteristics of key strata fracture-bearing structures and surface subsidence in shallow coal seam mining, with a focus on the 1–2 coal seam mining at Longhua Coal Mine in northern Shaanxi as the research background, this study employed physical similarity simulation to establish the correlation between key strata fracture-bearing structures and surface subsidence. The study also utilized theoretical calculations to develop models for the trapezoidal hinged arch structure and the coupling between key strata-bearing structures and surface subsidence. Mechanical properties of bearing structures and the coupled evolution characteristics of surface subsidence were examined, and the scientific validity of the models was verified through field monitoring. The research reveals that the inclined section of the working face in shallow coal seam mining forms a trapezoidal hinged arch structure, where stress transmission actually resembles an arch shape. Based on the fracture characteristics of rock strata, this structure can be categorized into three types: a full-trapezoidal hinged arch structure, a semi-trapezoidal hinged arch structure, and a trapezoidal-like hinged arch structure. A mechanical calculation model for the trapezoidal hinged arch structure was constructed, and the mechanical calculation formula for this structure was derived based on mechanical equilibrium conditions. Using a masonry beam mechanical model, the formula for calculating the subsidence of key blocks in the key strata fracture was obtained. Based on the “masonry beam” mechanical model, a formula was derived to calculate the subsidence of key blocks in fractured key strata. The relationship between key strata-bearing structures and surface subsidence curves was analyzed, leading to the development of a calculation model for both. This model reveals the coupled evolution between rock movement and surface subsidence. Field measurements indicate a maximum surface subsidence of 1.93 m, with a subsidence coefficient of 0.65, showing that the surface helps suppress and reduce the overall subsidence.

Polyaniline‐Doped Textile‐Based Triboelectric Nanogenerator: Self‐Powered Device for Wearable Electronics

ABSTRACTThe emergence of wearable electronics in contemporary lifestyles has spurred the need for smart fabrics capable of harnessing biomechanical energy. In the present study, a flexible polyaniline‐doped textile‐based triboelectric nanogenerator (PT‐TENG) is designed to harvest low‐frequency mechanical vibrations and convert them into electricity. For the device fabrication, five different textile fabrics are doped with conducting PANI, which is utilized as the tribopositive material, PVC thin film as the tribonegative material, and Al foil as electrodes. The PT‐TENG works in vertical‐contact separation mode, devised in arch structure for easy and complete contact between the working layers. Interestingly, the device featuring a PANI‐doped silk fabric generated the highest output voltage of 257.68 V and a current of 5.36 μA, respectively. Additionally, the PT‐TENG exhibits mechanical durability and electrical stability during continuous 7000 cyclic operations. Furthermore, the PT‐TENG showcases practical applications such as charging commercial capacitors, powering green LEDs and smartwatches, and as a self‐powered touch sensor. Thus, the PT‐TENG offers a facile fabrication process and robustness, highlighting its potential for sustainable energy harvesting in wearable electronics.

Розрахунок несної здатності аркової дорожньої споруди з гофрованого металу аналітичним способом

Introduction. One of the possible options for a simple, practical design of an arched road structure (small bridge) made of corrugated metal is considered, which can be considered as one that is more accurate and labor-intensive for the design of such a structure under the road pressure, as the “structure – soil” system for finite element method. Problem Statement. Regular normative and methodological documents for the design and maintenance of road structures (culverts, small bridges, tunnels) made of corrugated metal provide a simple formula for the structure of the structure and deformation of the body for such structures round pipes. The world is constantly streaming a wider range of rational and fairly simple types of road structures. Purpose. To show one of the possible ways of calculating an arched road structure made of corrugated metal on the basis of generally accepted initial provisions and a simple, understandable calculation scheme is the goal and task of this work.

Про тимчасове навантаження на аркові споруди з гофрованого металу під дорожнім насипом

Introduction. The issue of features of formation and practical calculation of temporary moving load from vehicles on arched structures made of corrugated metal under the road embankment is considered. These features are related to the scheme of static work and deformation of a relatively flexible structure — mainly to bending under the influence of the prevailing vertical pressure from the soil of the embankment and in the conditions of the transfer of a temporary load through the soil of the embankment, which distributes this load in a certain way. Problem Statement. In the current regulatory and methodological documents regarding the design of bridges and pipes, information on the rules for determining the amount of temporary moving load on pipes under highway embankments is limited to instructions regarding the parameters of a typical scheme of wheel loads (NK-100 or NK-80) and regarding the distribution of properties of the soil of the embankment, without setting out the methods and formulas necessary for practical calculations, which complicates the design to a certain extent. Normative and methodical documents directly related to the design of road structures made of corrugated metal also do not contain sufficiently complete and correct information on this issue.

Correlation of Radiological and Pedobarographic Evaluations in the Presence of Foot Sole Pain

Objective: One of the reasons for foot pain is the changes in the structure of the medial longitudinal arch. Assessment of medial longitudinal arch height is often made with foot radiographs and pedobarographic measurements. The relationship between these methods in the presence of foot sole pain has not been examined yet. This study aims to investigate the relationship among these measurement methods in adults with foot sole pain. Materials and Methods: 60 adults with foot sole pain were included in this study. The talohorizontal, talocalcaneal, talo1.metatarsal, and calcaneal inclination angles were measured in the lateral weight bearing foot radiographs. The arch index was calculated in static, dynamic pedobarographic measurements. The agreement of radiological and pedographic measurements among themselves and with each other was determined. Results: The mean age of 60 participants was 45.32 ±13.64. Agreement among foot classifications of radiologic measurements was poor Gwet’s agreement coefficient =-0.198 with a 95% confidence interval (-0.315,-0.080); percent agreement = 0.167 with a 95% confidence interval (0.099,0.234) and Kappa =-0.047 with a 95% confidence interval (-0.083,-0.01) were found. The agreement between pedobarographic classifications was fair Gwet’s agreement coefficient =0.486 with a 95% confidence interval (0.355,0.617); percent agreement =0.65 with 95% confidence interval (0.563,0.737) and Kappa=0.453 with a 95% confidence interval (0.324,0.583) were found. Among radiological measurements, the calcaneal inclination angle showed the highest coefficients of agreement with pedobarographic measurements. The extent of its agreement was fair. Conclusion: Pedobarography is a simple, reliable, inexpensive, and noninvasive method. The calcaneal inclination angle which is used in radiological imaging can give an idea about the height of the medial longitudinal arch.

A fast-filament eruption observed in the Hα spectral line

Context. Solar filament eruptions usually appear to occur in association with the sudden explosive release of magnetic energy accumulated in long-lived arched magnetic structures. The released energy occasionally drives fast-filament eruptions that can be the source regions of coronal mass ejections. A quantitative analysis of high-speed filament eruptions is thus essential to help elucidate the formation and early acceleration of coronal mass ejections. Aims. The goal of this paper is to investigate the dynamic processes of a fast-filament eruption by using unprecedented high-resolution full-disk Hα imaging spectroscopy observations. Methods. The whole process of the eruption was captured in a wide spectral window of the Hα line (±9.0 Å), which allowed for the detection of highly Doppler-shifted plasma. By applying the “cloud model” and obtaining two-dimensional optical thickness spectra, we derived the Doppler velocity; the true eruption profiles (height, velocity, and acceleration); and the trajectory of the filament eruption in 3D space. Results. The Doppler velocity maps show that the filament was predominantly blueshifted. During the main and final process of the eruption, strongly blueshifted materials manifest, traveling with velocities exceeding 250 km s−1. The spectral analysis further revealed that the erupting filament is made of multiple components, some of which were Doppler-shifted approximately to −300 km s−1. We found that the filament eruption attains a maximum true velocity and acceleration of about 600 km s−1 and 2.5 km s−2, respectively, and its propagation direction deviates from the radial direction. On the other hand, downflows manifested as redshifted plasma close to the footpoints of the erupting filament move with velocities of 45–125 km s−1. We interpret these redshifted signatures as draining material and therefore as mass loss of the filament, which has implications for the dynamic and the acceleration process of the eruption. Furthermore, we have estimated the total mass of the Hα filament, resulting in ∼5.4 × 1015 g.

Discrete element analysis of geosynthetic-reinforced pile-supported embankments

A discrete element trapdoor model was established using the MatDEM software, and the effects of different embankment and reinforcement heights on the soil arching effect of embankments under reinforced conditions were investigated by introducing a biaxial geogrid. The outcomes demonstrated that the inclusion of a geosynthetic reinforcement could enhance the load transfer efficacy of the embankment and thereby reduce the differential settlement of the embankment surface. The differential settlement could be reduced by approximately 50 % when the reinforcement height and the pile cap were close. The inclusion of the geosynthetic reinforcement helped reduce the development of the slip surface within the embankment above the reinforcement and prevented the vertical slip surface from continuing to move upwards, thus ensuring that the soil arching effect did not degrade too quickly and continued to play a role. In the case of a low embankment reinforcement, the soil arching effect was largely nonfunctional because of the rapid development of the vertical slip surface, and the load on the embankment in the soft soil was mainly transferred to the piles through the tensioned membrane effect of the geosynthetic reinforcement. For a high embankment with a low reinforcement height, the soil arch structure of the embankment was well maintained, the soil arching effect did not degrade, and the load on the embankment in the upper part of the soft soil was transferred to the piles via the soil arching effect along with the tensioned membrane effect. In the case of a high embankment with a high reinforcement, the reinforcement blocked the vertical slip surface only for the soil above the reinforcement height, whereas the vertical slip surface below the reinforcement height developed in line with that of the same height, when the tensioned membrane effect and soil arching effect worked together in the embankment above the reinforcement height, and the soil arching effect below the reinforcement height degraded and hardly played a role.

Design and application of a prefabricated structure for large-span arch open-cut highway tunnels

To enhance construction efficiency, improve lining quality, and reduce project costs, this study proposes a prefabricated arch structure scheme for large-span open-cut highway tunnels, specifically targeting the ongoing construction of an eight-lane open-cut tunnel on Chongqing’s Xinsen Avenue. By establishing a finite element “load-structure” integrated calculation model and adopting an iterative analysis method, the impact of joint stiffness variations on internal force distribution was determined. Combined with long-term field monitoring and measurements, a thorough analysis was conducted on the performance of the prefabricated arch structure during different construction stages. The results indicate that after assembly into a ring, the structure undergoes a self-adaptive adjustment phase, during which the joints experience significant stress and deformation. Following top-layer backfilling and water level restoration, the axial force on the joints increases, while stress and deformation decrease, exerting a positive effect on the joint bearing capacity. From the construction period to post-opening operations, the stress variation experienced by the joints remains within a controllable range, demonstrating substantial safety margins. This fully validates the safety and reliability of the prefabricated arch structure scheme.

Experimental and numerical investigation of arch concrete slabs subjected to underwater contact explosions with the inner arch side facing air

Arch structures with their inner arch side exposed to air and outer arch side exposed to water are often encountered in practical projects, and these engineering structures may be subjected to various explosive attacks during operation. This paper investigates the damage mechanism and dynamic response of arch concrete slabs with the inner arch side facing air against underwater contact explosions (UWCEs). The explosion tests of the arch concrete slab with the inner arch side facing air were carried out. The accuracy and applicability of the numerical model were verified by comparing with the explosion results. After that, the failure evolution and energy transition of the arch concrete slab with the inner arch side facing air were studied. The effects of different explosion masses, explosion distances, and reinforcement schemes on the antiknock performance of arch concrete slabs are further explored. The results show that as the explosive mass of UWCEs increases, the damage mode of the arch concrete slab with the inner arch side facing air changes from cracking along the longitudinal direction and local failure to spalling on the inner arch side and fragmentation of the contact specimens. The existence of curvature of the arch slab will cause the damage of the arch slab to intensify. The failure mode of the arch concrete slab changes from local failure to slight failure with cracks as the explosion distance increases. Increasing the longitudinal steel bars on the outer arch side can effectively inhibit the generation and development of cracks.

Asymmetric development of overburden fracture and gas migration law for a goaf of entry formed by roof cutting

AbstractIn the study, a combined numerical simulation and on‐site monitoring method was used to analyze the asymmetric development characteristics of overlying rock fractures in a goaf under the condition of a goaf side entry formed by roof cutting and to explore the gas accumulation area in the goaf, achieving precise gas extraction from the goaf. The results demonstrates that a double‐balanced arch structure is formed under the condition of a goaf side entry formed by roof cutting, achieving safe retention of the roadway and showing the significance of the pressure relief effect of roof cutting. The collapse movement of the overlying rock on the roof‐cutting side is relatively advanced. The heights of the collapse zone on the roof‐cutting side and the uncut roof side are 28 and 24 m, respectively, and the development heights of the fracture zone are 37 and 42 m, respectively. The fault line on the roof‐cutting side gradually shifts toward the direction of the goaf, and the surface settlement and fracture development are relatively small. There is a clear asymmetric structure in terms of time effect, fault line, fracture zone height, and surface settlement compared to the uncut roof side. The gas is distributed throughout the entire goaf in the roof‐cutting and tunneling mode, and a high‐concentration gas accumulation area is formed near the open–off cut and working face on the high side of the fracture zone. Based on an actual situation, a method of drilling high and low positions in a fracture zone is proposed for extraction. Combined with on‐site monitoring, the goaf was no longer filled with gas during extraction, and the proportion of low‐concentration gas space considerably increased.

Steel Arch Structures with Prestressed Concrete Deck

AbstractFootbridges with prestressed concrete deck, which are suspended on steel arch ribs, are described in terms of the structural arrangement, static function and erection. These bridges create stiff structural systems which guarantee the bridges' favourable dynamic response. While steel arch ribs allow easy erections, the concrete deck guarantees structural integrity. The footbridges are structurally efficient, they are light and transparent, corresponds to the scale of the landscape and all structural members have human dimensions. They were erected with a minimum impact on the environment. Their structural arrangement is illustrated on examples of four bridges.

Meta-arch structure: Designed reinforcement cage to enhance vibration isolation performance

In this study, inspired by the mechanical metamaterials with bandgap properties, a new type of meta-arch structure (MAS) for the attenuation of elastic waves is proposed. In this metastructure, the reinforcement cage, typically employed to enhance the tensile properties of building materials, has been redesigned and transformed into a new structure containing circular tubes with embedded resonant microstructures. The vibration reduction performance of the MAS was illustrated by the frequency response analysis in the simulation calculation, and the generation mechanism of the vibration attenuation band was revealed. The specimens of the complex MAS consisting of gypsum, reinforced steel bars, and tubes were fabricated, and the vibration response experiments were carried out to determine the dynamic properties of the novel MAS. The results show that the designed arch structure exhibits a broad vibration attenuation band without sacrificing its structural bearing capacity. Additionally, the robustness of the band gap is demonstrated by analyzing how changes in the positions of excitation and response points influence the band gap. Moreover, the MAS can be customized for specific application scenarios of vibration reduction according to the parameter analysis. Finally, the experimental results closely align with the numerical estimations, confirming the feasibility of the design method for reducing vibrations. This work provides a new method for the development of building structures for vibration and noise control.

Bracing systems for three-ribbed arch bridges against out-of-plane buckling

This paper is concerned with the design of bracing systems for three-ribbed parabolic arch bridges against out-of-plane buckling. Typical bracing systems for the three-ribbed arch bridges include K-bracing system and X-bracing system as well as transverse bracing system. The buckling criterion of the braced funicular three-ribbed arch bridge is derived from an exact matrix stiffness method (MSM) with a 14 × 14 s-order element stiffness matrix of three-dimensional beam-column elements that allows for torsional and warping deformations. The lateral torsional buckling load and mode are given by the lowest eigenvalue and eigenvector associated with the assembled structural stability stiffness matrix. A comparison study between different bracing system configurations suggests that the three-ribbed arches with the integral K- or X-bracing system (a K/X-bracing across the three arch ribs) have lower lateral torsional buckling loads than their arch counterparts with the independent K- or X-bracing system (the adjacent arch ribs are connected by K/X-bracing respectively), because the latter ones could provide more restraint on the middle arch rib to avoid early lateral torsional instability. Further, a bracing utilization efficiency index (defined as the normalized buckling capacity over material usage for bracing system) is proposed to quantify the effect of bracing systems in improving the lateral torsional buckling capacity of arch bridges. Highly efficient bracing systems that maximize the lateral torsional buckling load of three-ribbed arch structures with the lowest bracing material usage are then recommended.

Modular reconfigurable rotary style soft pneumatic actuators

Modular soft robots have the advantage in their ability to be reconfigured and change their morphology on-demand according to a specified task. The actuator design and particularly the inter-unit connectivity strength commonly govern the usability and functionality of these modular robots and their applications. In this paper, we present development of reconfigurable modular rotary soft actuators that allow the construction of highly versatile soft robotic actuators and systems. These pneumatically driven modular actuators are composed of an inner balloon and a flexible arched reinforcement structure to produce a rotary motion. They serve as building blocks which may be combined in various configurations to construct linear assemblies capable of extensile or bending motions. The connection scheme allows for the larger actuators to grow or shrink with the addition or removal of modules. Using finite element simulations and physical characterizations, we systematically explore the mechanical response of individual modular actuators and the role of various connection schemes on their motions upon pressurization. A key conceptual contribution of this work lies in the idea that for a modular soft robotic system, offsetting and tuning actuator alignment relative to an axis of symmetry can lead to substantial changes in mechanical performance. Utilizing these modules we demonstrate the reconfigurability of this modular system by both reconfiguring a large actuator into a pair of smaller actuators that can grasp delicate objects, and reconfiguring actuators to develop a linear crawling robot.

Experimental Study of the Mechanical Behavior of a Steel Arch Structure Used in the Main Lining of a Highway Tunnel

Experimental Study of the Mechanical Behavior of a Steel Arch Structure Used in the Main Lining of a Highway Tunnel

Differences in the Size of Individual Plantar Intrinsic Foot Muscles Between Ballet Dancers and Non-Dancers.

In classic ballet, choreography often involves tiptoe standing. Tiptoe standing requires a high and stable foot arch structure, which is achieved by contraction of the plantar intrinsic foot muscles (PIFMs). Long-term repetitive loading with a specific movement can induce hypertrophic adaptation of the associated muscles. For dancers, however, limited information on the size of individual PIFMs is available from previous studies. The purpose of this study was to determine the differences in the sizes of 10 individual PIFMs between dancers and non-dancers. Muscle volumes (MVs) of 10 individual PIFMs were measured using magnetic resonance imaging in 15 female dancers and 15 female non-dancers. Muscles analyzed included abductor hallucis, flexor digitorum brevis, abductor digiti minimi, quadratus plantae, lumbricals, flexor hallucis brevis, adductor hallucis oblique head, adductor hallucis transverse head, flexor digiti minimi, plantar/dorsal interossei. In addition to absolute MVs, relative MVs normalized to body mass (rMVBM) and the percentage of individual MVs relative to the sum of 10 individual PIFM MVs (%MVWHOLE) were calculated. The absolute MVs of 6 individual PIFMs, including the flexor digitorum brevis and lumbricals, were +16% to 59% larger in dancers than in non-dancers (P ≤ .048). The rMVBM of all individual PIFMs were +35% to 95% larger in dancers than in non-dancers (P ≤ .019). The %MVWHOLE of the flexor digitorum brevis and lumbricals were +10% to 36% higher (P ≤ .014) and those of the abductor digiti minimi and adductor hallucis oblique head were +8% to 11% lower (P ≤ .037) in dancers than in non-dancers. For all 3 MV measures, only the flexor digitorum brevis and lumbricals, which are functionally specialized for flexion of the second to fifth metatarsophalangeal joints, were consistently larger in dancers than in non-dancers. This may be due to long-term repetitive loading on these PIFMs during ballet training involving tiptoe standing.

Pelestarian Gapura Wringin Lawang Sebagai Potensi Sarana Edukasi di Trowulan

This research focuses on the preservation of the Wringin Lawang Gate, a cultural heritage site in Trowulan, Mojokerto, which has historical value as a relic of the Majapahit Kingdom. A descriptive qualitative approach is used to evaluate the physical condition, accessibility, community participation, and educational potential contained in this site. The findings show that although the arch structure is still sturdy, there is damage to certain parts due to age and weather factors. Access to this site is quite good, but the supporting facilities are still limited. Educational activities at the Wringin Lawang Gate are still not optimal and require the development of a more structured program. The participation of local communities in site preservation already exists, but needs to be increased through active involvement in education and conservation activities. Recommendations for site managers include improving educational programs through modern technology such as augmented reality, as well as the development of supporting facilities to maximize the potential of the Wringin Lawang Gate as an effective and sustainable educational facility.