Shear Force Distribution Research Articles

Turbulent flow and wall forces in staggered square cylinder porous media: An LES Analysis

Abstract The Wall-Modeled-Large Eddy Simulation (WMLES) technique was used to analyze turbulent flow in a porous medium composed of a staggered arrangement of square cylinders. The study focused on a porosity range of 0.3 to 0.8 at a pore Reynolds number of 10×103. The research provides novel information on pressure and shear force distributions around the cylinders and time-averaged values of particle drag and fluctuating lift coefficients. Results indicate that the flow physics are mainly driven by an expansion region in front of the central particle and another in the rear, where the flow is contracted and strongly accelerated. In the first region, velocities, turbulence kinetic energy (k), and its dissipation rate (e) are attenuated by a sudden pressure increase, while in the contraction region, the effect is the opposite. As porosity decreases, flow gradients and the overall levels of k, e, and Reynolds stresses become more significant. Turbulent anisotropy increases as porosity decreases below 0.6. Hydrodynamic stresses in the last interval present relatively uniform levels, which is a unique feature that may be considered in designing dedicated engineering devices with controlled stresses.

Shear strength of steel-concrete composite I-beams with corrugated steel webs

Corrugated steel webs have been widely applied to steel-concrete composite beams due to their excellent shear performance. However, there needs to be adequate research on the shear behavior of steel-concrete composite I-beams with corrugated steel webs, and the proportional distribution of shear forces between concrete flanges and corrugated steel webs in composite I-beams has yet to be clarified. This paper experimentally investigates steel-concrete composite I-beams with corrugated steel webs with different shear span ratios. With the increase of the shear span ratio, the shear failure mode of the beam gradually evolves from shear-dominated to flexural-dominated, the shear capacity and structural stiffness of the beam are negatively affected, and the improvement of the shear resistance of the beam after webs buckling is gradually limited. As the primary shear component, corrugated steel webs contribute about 71 % to 92 % of the total sectional shear force. Notably, accounting for 15 % to 35 % of the shear capacity of the beam, the shear contribution of the concrete flange must also be typically considered. For the generalizability of research results, parametric studies are conducted using validated numerical models to comprehensively investigate the effects of steel yield strength, concrete strength, web thickness, web height, and shear span ratio. Afterward, an efficient analytical model considering the shear capacity of the concrete flange is proposed to estimate the shear strength of composite I-beams with corrugated steel webs. The proposed analytical model agrees satisfactorily with experimental and numerical analysis results. The research results can provide valuable support for designing and optimizing steel-concrete composite I-beams with corrugated steel webs.

A method for calculating vector forces at human-mattress interface during sleeping positions utilizing image registration

The vector forces at the human-mattress interface are not only crucial for understanding the distribution of vertical and shear forces exerted on the human body during sleep but also serves as a significant input for biomechanical models of sleeping positions, whose accuracy determines the credibility of predicting musculoskeletal system loads. In this study, we introduce a novel method for calculating the interface vector forces. By recording indentations after supine and lateral positions using a vacuum mattress and 3D scanner, we utilize image registration techniques to align body pressure distribution with the mattress deformation scanning images, thereby calculating the vector force values for each unit area (36.25 mm × 36.25 mm). This method was validated through five participants attendance from two perspectives, revealing that (1) the mean summation of the vertical force components is 98.67% ± 7.21% body weight, exhibiting good consistency, and mean ratio of horizontal component force to body weight is 2.18% ± 1.77%. (2) the predicted muscle activity using the vector forces as input to the sleep position model aligns with the measured muscle activity (%MVC), with correlation coefficient over 0.7. The proposed method contributes to the vector force distribution understanding and the analysis of musculoskeletal loads during sleep, providing valuable insights for mattress design and evaluation.

Construction of highly stable, monodisperse water-in-water Pickering emulsions with full particle coverage using a composite system of microfluidics and helical coiled tube

Water-in-water (W/W) Pickering emulsions, exhibit considerable potential in the food and pharmaceutical fields owing to their compartmentalization and high biocompatibility. However, constrained by the non-uniform distribution of shear forces during emulsification or the spatial obstruction in polydimethylsiloxane (PDMS) passive microfluidic platform, the existing methods cannot generate monodisperse W/W Pickering emulsions with high particle coverage rate, thereby limiting their applications. Herein, a novel microfluidic system is designed for the preparation of monodisperse and highly particle-covered W/W Pickering emulsions under mild conditions. pH-responsive Polyethylene glycol (PEG)/phosphate aqueous two-phase system (ATPS) is used for the emulsions' preparation. Notably, a coverage rate of 96 ± 3 % is obtained by adjusting the length of the helical coiled tube, as well as the size and contact angle of genipin cross-linked BSA (BSA-GP) particles. Moreover, these W/W Pickering emulsions, with surfaces almost completely covered, can maintain monodisperse (Ncoal = 1.18 ± 0.03) for one day. Furthermore, the results of ranitidine hydrochloride (RH) release demonstrated that the drug release rate of W/W Pickering emulsions in the simulated gastric fluid (SGF) was 10 times faster than that in the neutral solution. We believe that the highly particle-covered monodisperse W/W Pickering emulsions possess great potential applications in bioencapsulation for foods and drug delivery.

Experimental research on the out-of-plane performance of traditional residential timber frame-wall with embedded metal connectors in central China

Traditional residential brick walls in central China typically employ metal connectors to connect with embedded timber columns for out-of-plane tensioning. To analyze the influence of metal connectors on the out-of-plane mechanical behavior of brick walls, several wall specimens were fabricated. The specimens comprised one without any connectors and three with different quantities of metal connectors placed at various locations. Static tests were conducted using gasbag loading. The deformation histories, failure modes, characteristic points of the specimens were obtained, and the shear force distribution patterns were analyzed. Furthermore, the influence of metal connectors on the collaborative performance of timber frames and brick walls in terms of their out-of-plane behavior was examined. The results indicate that walls partially equipped with metal connectors show an enhanced bearing capacity of around 17.50 % and the lateral deformation capacity of 28.38 % compared to walls without connectors. Furthermore, walls fully equipped with connectors show an increased bearing capacity by 22.51 % and lateral deformation capacity by 57.17 %. In comparison to walls without connectors, those fully equipped with connectors exhibit a 7.69 % increase in the column head shear force ratio. Consequently, the distribution of shear forces on column head is notably influenced by the presence of connectors.

Protection of Reinforced Concrete Columns from Pounding-Induced Effects in Adjacent Buildings

The pounding damage is one of the most common seismic damages observed after past earthquakes in adjacent reinforced concrete (RC) buildings having insufficient gap in-between. Particularly in highly populated regions, there are numerous adjacent RC buildings, in which pounding can cause severe damage or total collapse. Many previous reconnaissance reports following earthquakes have emphasized severe column damage due to pounding with the slab of adjacent building. In this paper, a retrofitting method is presented to reduce the seismic damage caused by pounding on existing RC structural elements in cases where collision is unavoidable. Pounding effects are investigated by using 4- and 7-story RC buildings with unequal floor elevations. As a retrofitting solution for pounding, steel columns and neoprene rubber pads are placed at the mid-height of the story so that the pounding takes place between the neighboring slab and added steel columns instead of existing RC columns. The mid-column pounding of existing RC buildings with and without retrofitting are numerically investigated. In the numerical model, buildings are connected by link elements to reproduce the pounding in-between. Nonlinear response history analyses are performed using 11 different real ground-motion records. Pounding forces, peak floor accelerations, inter-story drift ratios, story shear force distributions, and plastic hinge distributions are obtained and compared for each of the pounding conditions. The analysis results revealed that the proposed retrofitting method protects the existing RC columns from brittle type of shear failure and reduces the destructive effects of pounding.

A Numerical Simulation Study on the Out-of-Plane Performance of Timber Framework–Brick Wall Systems in Traditional Residential Buildings of Northern China

To improve the out-of-plane collaborative performance of timber frames and walls, a metal connector is proposed and designed. A finite element model of the wall is established, and the composite block damage criteria and surface contact behavior are validated. Additionally, one group without metal connectors and three groups with different numbers of metal connectors placed at various positions in traditional residential wall models are established. Using static loading simulation, the influence of different numbers of metal connectors on the out-of-plane damage patterns, deformation characteristics, and shear force distribution is analyzed. The study reveals that top metal connectors significantly reduce the out-of-plane displacement of the top wall by up to 84.6%. Metal connectors have a significant impact on the deformation capacity of brick walls, with a maximum enhancement of 65.3%. The metal connectors in the middle and lower parts transfer the wall loads to the columns, increasing the horizontal shear at the column head by approximately 7%. The connectors in the middle and lower parts effectively improve the collaborative performance of brick walls and wooden frames.

To Study the Behaviour of Single Pile Foundation Under Vertical Loading using Geo 5’’

The objective of the project is to analyze a pile foundation and determine it’s load bearing capacity by static method and a software and compare the results. This project includes the analysis of pile formed on black cotton soil at site of the “Galaxy Sky Residency” Miraj.. The calculations were carried out using the commercial software GEO5 from FINE Inc. This software computes the load-displacement curve on the pile head and the distribution of normal and shear forces along the shaft. The shear behavior of the pile-soil interface is de-scribed according to a modified Mohr- Coulomb’s theory. This paper also focuses on the de-termination of parameters of strength (angle friction and cohesion) and settlement (Young modulus) for deep foundation. The use of GEO4 for foundation design is explained in details herein.

Development of chia oil-in-water nanoemulsions using different homogenization technologies and the layer-by-layer technique

Aim: The present study investigates the influence of various homogenization techniques, namely high-pressure valve homogenization and microfluidization, and different forms of modified sunflower lecithin, including deoiled (DL) and hydrolyzed (HL) variants, on the development of monolayer and bilayer nanoemulsions of chia oil. Methods: Oil-in-water (O/W) nanoemulsions with 5% chia seed oil were prepared using simple (0.5% DL or HL) or double-layer [0.5% DL or HL and 0.3% chitosan (Ch)] stabilization. This involved a two-step homogenization process, utilizing either microfluidization or high-pressure valve homogenization. Chia oil nanoemulsions were characterized by their zeta potential, particle size, and rheological properties. Besides, their physical stability and omega-3 content during refrigerated storage were evaluated. Results: Overall, the studied modified sunflower lecithin (DL and HL) demonstrated effective capability in stabilizing chia nanoemulsions and facilitating the formation of the double-layered structure following Ch deposition. Concerning the homogenization method, it has been demonstrated that under the same homogenization conditions, microfluidization resulted in significantly smaller droplet sizes and higher apparent viscosities compared to high-pressure valve homogenization. This discrepancy can be attributed to the design of the homogenization chambers, as microfluidization generates a narrow distribution of shear forces, while high-pressure valve homogenization yields a much broader distribution. In contrast to chia monolayer nanoemulsions, the nanoemulsions stabilized by modified sunflower lecithin-Ch demonstrated a noteworthy improvement in their overall stability. This enhancement can be ascribed to their increased apparent viscosity and the highly charged interfaces of the droplets. Furthermore, throughout the entire refrigerated storage period, the omega-3 content in all nanoemulsions remained unchanged. Conclusions: In this study, mono and bilayer chia oil nanoemulsions were successfully obtained using modified sunflower lecithin and high-energy techniques. Microfluidization outperformed high-pressure valve homogenization, resulting in smaller droplets and increased viscosity. These findings are relevant for designing stable

A new finite element formulation for the dynamic analysis of beams under moving loads

Early studies highlighted the fact that moving loads on beams may induce significantly higher dynamic deflections and stresses than those observed in the quasi-static case. Since then, the dynamics of beams under moving loads has been an active research area, in particular for the past decades, with the rapidly increasing computer power allowing the development of highly robust and sophisticated computational and numerical methods in applied mechanics and engineering. This work introduces a novel finite element formulation for the dynamic analysis of Euler-Bernoulli beams subjected to moving loads. The formulation is consistent with a complementary form of the well known Hamilton's variational principle, and will be used to address some numerical tests in both modal and time domains. The effectiveness and accuracy of the formulation will be assessed and discussed by comparison between the obtained results and those rendered by the standard displacement-based finite element formulation. As it will be demonstrated, the proposed formulation not only renders continuous bending-moment and shear-force distributions, a desired feature in the structural design field, but also has a superior accuracy than that provided by the displacement formulation that uses the same number of nodal degrees-of-freedom.

Shear strength of corrugated web girders with compression tubular flanges

The current paper focuses on the shear strength of corrugated web girders with compression tubular flanges (CWGCTFs) which considers the real web-flange juncture behaviour. Accordingly, the real juncture behaviour between the corrugated web (CW) and compression tubular flange in CWGCTFs used in conventional buildings is explored first. An elastic bifurcation buckling analysis is carried out using the finite element (FE) software ABAQUS for isolated CWs with different boundary conditions at their juncture with the flanges. ِAssuming that the dimensions of the generated CWs depend on those of conventional buildings, it is found that the corresponding embedment of the CW by the flanges of the CWGCTFs acts as a fixed connection. Having identified the real web-flange juncture behaviour, a large number of nonlinear FE models are generated to obtain the shear strength of the CWGCTFs taking into account the geometrical imperfection and material nonlinearities. This has been done based on a validation recently presented by the authors. The FE strengths are then compared with available shear strength predictions for CWGs with plate flanges (those of Driver et al. (2006), Moon et al. (2009), Sause and Braxtan (2011), Nie et al. (2013), Leblouba et al. (2017)) as well as on the derived shear force distribution relation for tubular flange and CW of CWGCTFs of the current authors (2022). Finally, the shear strength of CWGCTFs proposed by Leblouba et al. (2017) is modified to design the shear strength of CWGCTFs.

Seismic performance of a frame‐supported shear wall over‐track building through shaking table test

SummaryThis research deals with a frame‐supported shear wall for urban over‐track building of vehicle depot in Chisha, Guangzhou, China, which is characterized by its remarkable height of 160.8 m. Technical issues are commonly encountered in these kinds of buildings due to discontinuous vertical structural rigidity, large podium, and structural transition. These challenges significantly impact the engineering process, especially when the rigidity difference between transfer story exceeding the threefold, as well as the building height exceeds limit as in code. In this paper, a shaking table test was developed based on a 1:10 scaled model of the structure. Using similarity theory, the dynamic similarity relationship was established for the design of the model. Subsequently, the experimental model was constructed with the configuration of critical parameters such as mass design, sensor placement, and seismic test conditions. This was followed by in‐depth analysis, recording component failures and investigating key aspects such as dynamic characteristics, that is, acceleration and displacement responses and shear force distribution under different earthquake intensities. A theoretical seismic response of the prototype structure was derived from the test results. The shaking table tests confirmed that the structure met the stringent seismic design requirements as prescribed in the Chinese standards, with no damage under minor earthquakes, repairability under moderate earthquakes, and collapse prevention under rare earthquakes. The results of the study provide valuable insights along with improvement measures for the design and development of similar urban over‐track buildings, potentially contributing to more efficient land use in urban China.

Study on the Effect of Three-dimensional Reconstruction Technique Based on Human Gait Plantar Transient Data on Rehabilitation of Patients with Abnormal Foot Arch

This research employs non-contact plantar 3D data scanning and gait analysis methodologies to establish a rehabilitation assistance system tailored for foot arch anomalies. The system utilizes a non-contact plantar 3D data model to mitigate dysfunctions within the plantar skeletal-muscular system. Its objectives include facilitating personalized remote diagnosis of foot arch anomalies, enabling patients to monitor their rehabilitation progress, and supporting at-home rehabilitation efforts. A dataset comprising 124 cases of physiological foot arch anomalies in adults aged 18 and above was collected and analyzed. The findings demonstrate the system’s flexibility, high spatial resolution, personalization, and innovation. Notably, the system achieves real-time measurement of positive pressure and shear force distribution at the plantar interface, facilitates the construction of accurate geometric models, and yields high-quality plantar three-dimensional coordinate data. This research contributes theoretical and technical underpinnings for the application of footwork anomaly diagnosis and correction.

Gravitational form factors of the nucleon and one pion graviproduction in chiral EFT

In the framework of chiral effective field theory of delta resonances, nucleons, and pions interacting with background gravitational field we calculate the gravitational form factors of the nucleon up to fourth order in the small scale expansion and obtain the long-range behavior of the corresponding contributions to the energy, spin, pressure, and shear force distributions. By comparing nucleon gravitational form factors with and without delta contributions we conclude that explicit inclusion of deltas plays an important role. Next we explore the Lorentz structure of the N↦Nπ transition matrix element of the conserved symmetric energy-momentum tensor and introduce its parametrization in terms of twelve transition form factors. We use the chiral effective field theory to calculate the tree-order contributions to the gravitational transition form factors of the pion graviproduction off the nucleon up to third order. Published by the American Physical Society 2024

Impact behavior of high-strength steel beam with different web opening forms

This paper investigates the performance of high-strength steel beams with web openings (HSSBWOs) under impact by methods of tests and finite element. Based on the experimental data of 10 specimens, which were made of high-strength steel Q550D, and the effects of impact energy and web opening forms on the impact behavior of HSSBWOs are investigated emphatically. In particular, two specimens made of steel Q235D were used to study the differences in impact behavior from HSSBWOs. The test results reveal that the high-strength steel beams with circular web openings (HSSBCWOs) have better impact resistance than the high-strength steel beams with hexagonal web openings (HSSBHWOs), and the HSSBWOs have better impact resistance than the normal-strength steel beams with web openings (NSSBWOs). Moreover, HSSBWOs has excellent abilities to absorb energy, the average energy absorption rate of HSSBHWOs and HSSBCWOs is 95.78% and 93.55%, respectively. In addition, finite element models that can accurately predict the dynamic responses of HSSBWOs under impact load are established to analyze the shear force evolutions, as well as investigate the differences of impact behavior between steel beams with a variety of web openings forms. The results show that the shear force distribution ranges of HSSBCWOs are larger than that of HSSBHWOs at the time when impact force reached peak value. The HSSBWOs can sustain more impact load with the web opening shape that closer to the circle. The solid webbed steel beam (SWSB) has better impact resistance than the steel beams with web opening (SBWO).

Heat transfer characteristics of water jet impingement on high-temperature steel plate by angular nozzle

The average jet flow rate, vapor volume fraction inside the nozzle, and the distribution of pressure, shear force, turbulence intensity, temperature, and Nusselt number on the heat transfer surface were simulated when water jet impinged on a 900 °C steel plate by a straight cone nozzle and an angular nozzle under the condition of 0.7 MPa inlet pressure. Results indicate that the strong cavitation effect of the angular nozzle makes its jet impingement heat transfer intensity superior to the straight cone nozzle. Although the average jet flow rate of the angular nozzle is 3.33% lower than that of the straight cone nozzle, its shear force, turbulence intensity and Nusselt number at the stagnation point are 18.43%, 20.43%, and 18.81% higher than those of the straight cone nozzle. Experiments also show that the jet impingement heat transfer intensity of the angular nozzle is better than that of the straight cone nozzle. Its maximum cooling rate at the stagnation point increased by 13.16%, and the time to reach the maximum cooling rate decreased by 60%, compared with the straight cone nozzle. It is hoped that the results can help improve the performance of online cooling equipment for hot-rolled steel.

Study of the Mechanical Behavior of Retaining Structures and Adjacent Buildings during the Excavation of Deep and Long Pits

Excavation of deep and long pits can cause strata deformation and settlement of adjacent buildings. The excavation of a deep foundation pit of a nearby building in Zhengzhou City, China, is taken as the research object. The foundation of the foundation pit is an independent foundation under the column, the depth of the foundation pit is 24.5∼26.3 m, and the support form of an underground continuous wall and four internal supports is adopted. The stress and deformation characteristics of retaining structures during the construction of deep and long pits and their impact on the deformation of nearby buildings were studied through on‐site monitoring and finite element simulation. The analysis focuses on the effects of different excavation stages on adjacent structures, with the main conclusions as follows. After excavation, the underground continuous wall far from the building undergoes a “rotating‐kick” displacement, while the underground continuous wall on the side near the building only shows a “kick” displacement. Adjacent buildings have little influence on the distribution of shear force and bending moment of the underground continuous wall of the foundation pit. The first horizontal strut experiences pressure, gradually shifting to tension as excavation continues, with the maximum stress reaching 3.6 × 103 kN. The second, third, and fourth horizontal struts mainly bear compressive forces, increasing with the depth of the struts. The building primarily undergoes settlement in the early stages of deep and long pit excavation. As the excavation progresses, the building points near the pit begin to bulge, but the building corners far from the pit continue to show settlement. During the excavation of the deep and long pit, the differential settlement of the long side of the nearby building first decreases and then increases, and the differential settlement of the short side changes from a slight decrease to a significant increase. The settlement evolution of the building is as follows: overall settlement ⟶ overall uplift ⟶ uplift of the side of the building near the pit ⟶ outward tilting away from the pit. The findings may provide references for designing, constructing, and operating deep and large foundation pits.

Shear force distribution mechanism of perfobond leiste connectors in joint between corrugated steel web and concrete top slab

Compared to composite bridges with flat steel webs (FSWs), the corrugation shape and significant shear deformation of the steel web in composite bridges with corrugated steel webs (CSWs) will influence the distribution and magnitude of the shear force of connectors in the joint between the steel web and concrete slab. However, these effects have not been considered in current design specifications, which may lead to unsafe designs. This paper investigates the shear force distribution mechanism of perfobond leiste (PBL) connectors in the joint between the CSW and concrete top slab in composite bridges with CSWs. The theoretical solution for the shear force of the joint per unit length is firstly derived based on the elastic bending theory considering the shear deformation of the CSW. Then, finite element simulations using hybrid models of solid and spring elements are conducted to further investigate the shear force distribution of PBL connectors and influencing parameters. The results show that the shear deformation of the CSW has a negligible effect on the shear force of the joint per unit length. In contrast to composite bridges with FSWs, the CSW induces sinusoidal variations in the shear force of PBL connectors, which leads to an increase in the shear force of partial PBL connectors. The amplification factor for the shear force increases with the wavelength of the CSW and the shear stiffness of the PBL connector, while it decreases with the increasing dimensions of the steel upper flange, perforated ribs, and hole spacing. Finally, a calculation formula and corresponding procedure are proposed for predicting the shear force of PBL connectors in the joint between the CSW and concrete top slab for composite bridges with CSWs.

Experimental Study on Failure Mode of Precast Assembled Segmental Beams under Impact Loading

Precast segmental girder bridges are threatened by impact loads during service, but there is currently little research on the impact behavior of such bridges. This study investigated the dynamic responses and failure modes of precast assembled segmental beams experimentally and numerically. 10 beam specimens were designed for static and impact tests, respectively. Numerical simulations were conducted in LS-DYNA and verified by comparing them with the test results. Failure mechanisms were analyzed by verified models. The results show that the local shear failure mechanism is prominent under impact loading. Two typical failure modes were obtained: oblique section failure and joint section direct shear failure, which are related to the relative positions of joint and impact point. Confining stress can effectively improve the static bearing capacity and impact resistance, but has little effect on the early response and final failure mode. The main failure cracks occur near the joint bottom in the initial stage of impact, when the impact force is resisted by the inertia force, resulting in a characteristic “N” shape in shear force distribution. Shear failure of the joints dominates the beam failure mode. A dynamic shear span ratio can evaluate the early force characteristics of the joint section.

Mechanical response of concrete pipe rehabilitated by liner under external load: Analytical solution

AbstractUsing pipe lines to rehabilitate concrete drainage pipes is a popular trenchless technique. In this paper, the concrete pipe and liner are equivalent to a symmetrical structural mechanics problem, and the mechanical solution of the composite structure is obtained using the force method. Subsequently, the analytical solutions are compared with the test and finite element results. The distribution law of axial force, bending moment, and shear force of the composite structure are obtained, and the circumferential strain law of the inner and outer surfaces of the host pipe is analyzed. Lastly, the influence of pipe diameter and liner thickness on the bearing capacity of the host pipe is examined. The results indicate that the axial and shear force distribution of the composite structure remains the same for different pipe diameters, as the distribution diagrams of shear and axial force along the circumferential direction coincide. While the elastic modulus and thickness of the liner have no effect on the internal force distribution of the composite structure, they do directly affect the stress state of the host pipe. Additionally, the bottom support causes abrupt changes in the bending moments and strains of the host pipe.