Distribution Of Tensile Forces Research Articles

Evaluation of design parameters for geosynthetic reinforced-soil integrated bridge system based on finite element analysis

This study evaluates the performance of a geosynthetic reinforced soil integrated bridge system (GRS-IBS) in terms of total displacement by varying different design parameters simultaneously and also suggests optimum values of them. These parameters include, i. backfill internal friction angle (∅b) and reinforcement spacing (Sv), ii. Backfill internal friction angle (∅b) and geogrid axial stiffness (EA) at varying reinforcement spacing (Sv), iii. Backfill internal friction angle (∅b) and number of bearing bed layers, and the effect of retained backfill slope (mb). Simulations were conducted using PLAXIS 2D software. Analysis showed that the cumulative effect of these parameters had a significant effect on total displacement but after a certain point increase or decrease in their values showed no effect on the results while some parameters showed negligible effect on the deformation of the wall. Furthermore, due to the notable effect of ∅b, Sv and EA on the total displacement of the wall, the impact of these parameters was also investigated on the development of tensile force in the topmost layer of geogrid in GRS IBS. It was noted that the shape of the tensile force distribution graph was the same for all the cases and the order of the parameters in terms of their effect on tensile force was Sv > ∅b > EA. Also, a detailed analysis of tensile force development in all the layers of geogrids showed that if Sv ≤ 0.2 m, the spacing between reinforcement in the lower portion of GRS IBS can be increased as these layers showed approximately zero tensile load.

The influence of supports stiffness on the cable nets force distribution and geometry

This paper presents the initial stage of the design process of elastically supported cable net roofs. The form-finding and static analyses with large deformations are performed for two examples of structures. In both cases, the influence of real supports stiffness on the tensile force distribution and geometry of cable nets was compared. It was confirmed that it significantly influences designing of the final cable net configuration

Prediction and validation of geogrid tensile force distribution in back-to-back MSE walls under rail axle load: finite-element and intelligent techniques

Prediction and validation of geogrid tensile force distribution in back-to-back MSE walls under rail axle load: finite-element and intelligent techniques

Physical and Numerical Models of Mechanically Stabilized Earth Walls Using Self-Fabricated Steel Reinforcement Grids Applied to Cohesive Soil in Vietnam

Mechanically stabilized earth (MSE) walls have been widely applied in construction to maintain the stability of high embankments. In Vietnam, imported reinforcement materials are expensive; thus, finding locally available materials for MSE walls is beneficial. This study examines the behavior of an MSE wall using local reinforcement materials in Danang, Vietnam. The MSE was reinforced by self-fabricated galvanized steel grids using CB300V steel with 3 cm ribs. The backfill soil was sandy clay soil from the local area with a low cohesion. A full-scale model with full instrumentation was installed to investigate the distribution of tensile forces along the reinforcement layers. The highest load that caused the wall to collapse due to internal instability (reinforcement rupture) was 302 kN/m2, which is 15 times greater than the design load of 20 kN/m2. The failure surface within the reinforced soil had a parabolic sliding shape that was similar to the theoretical studies. At the failure load level, the maximum lateral displacement at the top of the wall facing was small (3.9 mm), significantly lower than the allowable displacement for a retaining wall. Furthermore, a numerical model using FLAC software 7.0 was applied to simulate the performance of the MSE wall. The modeling results were in good agreement with the physical model. Thus, self-fabricated galvanized steel grids could confidently be used in combination with the local backfill soil for MSE walls.

A simplified analysis of a configuration of geosynthetic reinforcement in GRPS embankments

Geosynthetic-reinforced and pile-supported (GRPS) embankments are increasingly used in recent years to reduce the differential settlement and increase the bearing capacity of the embankments. A new theoretical model is proposed to calculate the tensile force distribution and cross-sectional configuration of the geosynthetic reinforcement used in the Geosynthetic-reinforced and flexible pile-supported GRRPS and Geosynthetic-reinforced and rigid pile-supported GRFPS embankments. The accuracy of the proposed methods is verified by the results from laboratory model tests, centrifuge model tests and theoretical models in the literature. It is found that the tensile forces along the geosynthetic are distributed unevenly both in GRRPS and GRFPS embankments with the maximum and minimum magnitudes located at the edge and centre of the pile cap, respectively. The soil arching effect contributes more to the bearing capacity of the GRPS embankment than the membrane effect. It is found through the analyses of the centrifuge and model tests data that the soil arching effect contributes 65–75% of the total load transfer efficiency.

Study of the behavior of an instrumented soil nail wall in Salvador-Brazil

This paper aims to analyze the behavior of a soil-nailed excavation located in Salvador, Bahia, Brazil. Numerical stress-strain modeling was conducted, using finite element method. The horizontal displacement profiles obtained for the wall face in the numerical analysis presented a good correlation compared to field instrumentation monitoring with inclinometers. The results showed that the magnitude of the maximum numerical and experimental displacements was lower than the simplified models recommended by international manuals and technical literature. However, the monitoring data was compatible with other cases of instrumented nailed excavations in silt-sandy soil in the city of Salvador. Numerical models also adequately represented the distribution of tensile forces in nails. The maximum tensile forces observed numerically were smaller than those calculated using analytical methods. It was emphasized that the results of field monitoring and numerical models correspond to a stage immediately after the end of the retaining structure execution, not considering the evolution of deformations in long term.

Analysis of reinforced soil wall for c–ϕ backfill considering Rayleigh wave

Analytical methods to analyse the seismic stability of reinforced soil walls showing the effect of Rayleigh waves are not available to date. In this study, the pseudo-dynamic approach was used to determine the seismic behaviour of a reinforced soil wall considering the propagation of primary, shear and Rayleigh waves. A mathematical derivation is proposed to obtain the required strength of reinforcements, the critical angle of the failure wedge and the factor of safety (FS) of the reinforced soil wall. The non-linear distribution of tensile force in the reinforcements can easily be obtained for the case of c–ϕ backfill using the results from the present parametric study. A sizable effect of horizontal ground acceleration and soil amplification factor on the required strength of reinforcements, critical angle of failure wedge and FS was observed. The trends found for Kmax and FS clearly emphasise the prominence of Rayleigh wave consideration in the analysis.

Finding the Optimal Surgical Incision Pattern-A Biomechanical Study.

The closure of wounds and subsequent optimal wound healing is essential to any successful surgical intervention. Especially on parts of the body with limited possibilities for local reconstruction, optimal distribution of load is essential. The aim of the present study was therefore to examine three different incision patterns, conventional straight, Lazy-S and Zigzag, with regard to their biomechanical stability and mode of failure on a porcine skin model. Our results demonstrate the superior biomechanical stability of Lazy-S and Zigzag incision patterns with perpendicular suture placement. This holds true, in particular, for Zigzag incisions, which showed the highest values for all parameters assessed. Moreover, the observed superior stability of Lazy-S and Zigzag incision patterns was diminished when sutures were placed in tensile direction. The conventional straight incision represents the standard access for a large number of surgical procedures. However, we were able to demonstrate the superior biomechanical stability of alternative incision patterns, in particular the Zigzag incision. This is most likely caused by an improved distribution of tensile force across the wound due to the perpendicular placement of sutures. Moreover, this technique offers additional advantages, such as a better overview of the operated area as well as several cosmetic improvements. We therefore advocate that the surgeon should consider the use of a Zigzag incision over a conventional straight incision pattern.

ABOUT THE LAWS OF THE DISTRIBUTION OF THE TENSIONING FORCES OF THE CABLES IN UNDERWATER ANCHOR-CABLE MOBILE ROBOTS

Possibilities of synthesis of various laws of distribution of the tension force of cables in the modules of the anchor-cable mover are considered. The analysis of the features of several variants of the distribution of tensile forces is carried out.

Effect of reinforcement arrangement on dynamic behaviour of back-to-back mechanically stabilised earth walls

Reduced-scale shaking table tests were performed on steel-strip back-to-back mechanically stabilised earth (MSE) wall models to evaluate the effect of the overlap length of the reinforcements (LR) and the connection arrangement of the opposing walls on the distribution of tensile force along the reinforcements and the propagation mechanism of the shear bands. The reinforcement elements were fully instrumented and particle image velocimetry (PIV) was utilised to identify the shear zones in the body of the models. On the basis of the PIV results, the combination of a concave surface and an inclined plane was determined to be the failure surface in the models. It was concluded that connecting two opposing walls can prevent the formation of a failure wedge in a back-to-back MSE wall (BBMSEW). It was observed that the geometry of the failure surface in the BBMSEWs was not affected by a change in LR, but depended on the connection arrangement of the walls. It was found that, although the use of overlapping reinforcement instead of the direct connection of two walls caused further development of shear bands, it could be a good solution in reducing the mobilised reinforcement forces in BBMSEWs.

Study on mechanical and tribological properties of ternary fluororubber filled with four needles of zinc oxide

AbstractThis article deals with study of the influence of four‐needle zinc oxide (T‐ZnOw) on the basic mechanical properties of ternary fluororubber (FKM) and the frictional properties of FKM improved by four‐needle zinc oxide under different temperatures. T‐ZnOw/FKM composites were prepared by mechanical blending and hot molding after pretreatment with silane coupling agent. The hardness, tensile, tearing, rotating friction at normal temperature, and reciprocating friction at high temperature of FKM and T‐ZnOw/FKM were studied. The results showed that T‐ZnOw with needle‐like three‐dimensional (3D) structure can effectively decompose the point stress generated in the tensile process of the composite, and the uniform distribution of tensile force improves the fracture base point and final mechanical properties of the composite. Its unique 3D structure can reduce fatigue wear caused by extrusion plastic deformation of the matrix during the friction process. The friction coefficient and wear rate of materials were effectively reduced by the reduction of plastic deformation resistance and fatigue wear area in the process of friction. Especially at 200°C, the friction coefficient and wear rate of T‐ZnOw/FKM were reduced by 30% and 55.32%, respectively, by T‐ZNOW/FKM doping.

Time-dependent load transfer behavior of grouted anchors in laterite

The load transfer behavior of grouted anchors is time-dependent under long-term (creep) load. This study aims at investigating the time-dependent behavior of grouted anchors in laterite by both physical model test and theoretical simulation. A laboratory creep pullout model test of full-length-bond grouted anchor in laterite was carried out using a special developed apparatus. The creep pullout load–displacement response at anchor head and time history curves of axial strain were tested and presented. The creep behavior on the grout - soil interface was simulated using Merchant rheological model in theoretical simulation. By comparing the experimental data with predictions, the applicability of the proposed theoretical method was validated, and the time-dependent load transfer behavior of grouted anchors was discussed. The impacts of five model parameters on the time-dependent pullout response were further analyzed by parametric studies. It revealed that the tensile force distribution tends to be linear, and the shear stress distribution towards uniformity as time elapsed. Additionally, the time-dependent load transfer behavior for grouted anchors is influenced by the above parameters in various levels. This work provides insights into understandings of time-dependent behavior, and facilitates the service life design practice for grouted anchors embedded in laterite.

INFLUENCE OF ROOT SYSTEMS OF DECIDUOUS TREES ON SOIL REINFORCEMENT - A CASE STUDY FROM THE CARPATHIANS, POLAND

Forests play an significant role in the protection of slopes against shallow landslides, and the presence of the tree roots in the soil is considered the most relevant factor increasing its shear strength. Most research on root reinforcement carried out in the European mountains refer to coniferous tree species but there is still not enough information about the root systems of decidous trees and their role in enhancing the slope stability. The aim of this study was to determine root reinforcement of four typical tree species (European hornbeam, common birch, black locust and small-leaved linden) growing in the forests of the Polish Carpathians. The measurements of root systems were performed using the trench wall method and the root reinforcement values were calculated using two fiber-bundle models -RBMw and RBMe, which represented different approaches to tensile force distribution within the root bundle. Studies have shown that the hornbeam roots have the highest, and the black locust roots the lowest values of the tensile strength. Calculations showed that the values of root reinforcement obtained using the RBMw model are 17% higher than the ones calculated using the RBMe model. Root reinforcement values for common birch, black locust and small-leaved linden did not exceed 10 kPa, and in case of hornbeam they were about 20 kPa max. As part of the work, the parameters of the Root Distribution Model were estimated, which after integration with the bundle models allowed to determine the relation between the root reinforcement, the distance from the tree and its diameter.

Physical and numerical modelling of strip footing on geogrid reinforced transparent sand

This paper presents the results of laboratory scale plate load tests on transparent soils reinforced with biaxial polypropylene geogrids. The influence of reinforcement length and number of reinforcement layers on the load-settlement response of the reinforced soil foundation was assessed by varying the reinforcement length and the number of geogrid layers, each spaced at 25% of footing width. The deformations of the reinforcement layers and soil under strip loading were examined with the aid of laser transmitters (to illuminate the geogrid reinforcement) and digital camera. A two-dimensional finite difference program was used to study the fracture of geogrid under strip loading considering the geometry of the model tests. The bearing capacity and stiffness of the reinforced soil foundation has increased with the increase in the reinforcement length and number of reinforcement layers, but the increase is more prominent by increasing number of reinforcement layers. The results from the physical and numerical modelling on reinforced soil foundation reveal that fracture of geogrid could initiate in the bottom layer of reinforcement and progress to subsequent upper layers. The displacement and stress contours along with the mobilized tensile force distribution obtained from the numerical simulations have complimented the observations made from the experiments.

Conditions modelling of low-temperature cracks existence in the road upper layer

Cracks, including low-temperature cracks, reduce to the greatest extent road surfaces quality, increase the cost their repair. This problem is most relevant in the regions with seasonal soil freezing. The purpose of this study is to develop a model of interaction between the asphalt concrete layer and the underlying layer by means of friction and adhesion forces at a negative temperature, also the analyze the conditions low-temperature cracks formation of in the asphalt concrete layer, in order to reduce the risk of cracking. Methods: as a research tool used numerical methods of structural mechanics. Results: the study found that the distribution of tensile forces in the segment of an asphalt-concrete layer is approximated by a polynomial of the second order with a maximum in the middle of the length of the segment. Shear forces are unevenly distributed along the length of the segment; the intensity of the shear forces is equal to zero in the middle of the length of the segment. The greatest shear strains and stresses are localized near the transverse boundaries of the segment of the layer. A shear deformation can lead to an increase in the crack width. The validity of the numerical simulation results is confirmed by their consistency with the known analytical solution of the same problem.

Experimental investigation of forces along anchors subjected to dynamic loading under tension and compression in field tests

Full-scale field tests of dynamic rockfall have been performed on a flexible SPIDER Avalanche system to study the dynamic force distribution along the foundations under dynamic loading. Therefore, an anchor to measure dynamic tensile forces and a pile to measure dynamic compressive forces were each equipped with strain gauges. Furthermore, a static pull loading test with load steps of 1 min duration was performed on the anchor to highlight the difference between dynamic and static loading. Effective kinetic energies applied on the net of the SPIDER Avalanche system range from 25 to 492 kJ with impact velocities between 17 and 25 m/s. The results show that the dynamic forces close to the pile- and anchor head are higher and that they are decreasing with increasing distance of pile and anchor. However, the dynamic tensile force distribution is nonlinear over the length of the anchor, whereas the dynamic compressive force distribution is linear along the pile length. The comparison of static and dynamic tensile forces shows that dynamic tensile forces are depleted within a shorter distance of the anchor compared to the static tensile forces. Dynamic tensile forces present 25% less in value than the static tensile forces.

Analytical study on the tensile stiffness of headed stud connectors

In the theoretical or numerical analysis of composite/hybrid structures, headed stud connectors at the steel–concrete interface are usually modelled as linear spring elements; thus, their tensile stiffness will be an essential parameter to affect the tensile force distribution. This article investigates the tensile stiffness of headed stud connectors through theoretical analysis combined with the existing pull-out test results. The pull-out displacement of headed stud connectors from concrete blocks mainly includes two parts: one part is the elastic elongation of the stud rod and another is the axial displacement of the stud head in concrete blocks resulted from the concrete elastic deformation. Mindlin’s solution is employed to predict the second part displacement with the introduction of an unknown coefficient, which is estimated based on the existing headed anchor pull-out test results. Subsequently, an equation for predicting the tensile stiffness of headed stud connectors is proposed. The predicting tensile stiffness for headed stud connectors with various stud heights presents a good agreement with the pull-out test results. Meanwhile, neglecting the axial displacement of the stud head in concrete blocks, especially for relatively short height headed studs, will produce an overestimated tensile stiffness.

高强螺栓灌浆套管端板拼接节点试验研究

本文提出了一种新型H形截面钢高强螺栓端板拼接节点，即容错度较好的高强螺栓灌浆套管端板拼接节点。为研究此节点的受力性能，实验设计了2个足尺试件，对其进行静力加载破坏试验，分析节点的受力特性、承载力性能、高强螺栓的拉力分布规律及破坏模式，并同时设计2个试件与该节点对应的高强螺栓端板拼接节点进行受力性能的对比。试验结果表明：相较于高强螺栓端板拼接节点，该节点的抗弯承载力及延性提高较显著；抗剪承载力基本相同；受压区螺栓的拉力分布基本一致，受拉区螺栓的拉力分布，随着荷载的增大，其拉力始终小于高强螺栓端板拼接节点的受拉区螺栓。研究表明此节点由于端板上可以适当地开大螺栓孔径的大小而不影响其受力性能，故可以有效地解决高强螺栓的安装难度，便于施工现场安装。 A new type of flush endplate connection, named better-tolerance high-strength bolted grouted sleeve flush endplate connection, was developed for splice H-shape steel. In this paper, the static loading failure tests were conducted on two specimens in order to evaluate load transfer mechanism, strength capacity, tensile force distribution of high-strength bolts and failure mode of this type of connection, furthermore, the other two specimens of its corresponding type of high-strength bolted flush endplate connections were designed to compare their mechanical performances. The experimental results indicate that by comparing with high-strength bolted flush endplate connections, the bending capacity and ductility of high-strength bolted grouted sleeve flush endplate connections increases remarkably, the shearing capacity and the tension distribution of the bolts in the compression zone is basically the same, but with the increase of the load, the tension distribution of bolts in tension zone is smaller than the high-strength bolt endplate flush endplate connections. The results show that since the bolt aperture can be properly opened largely without affecting its mechanical performance, so this type of connection can effectively solve the installation difficulty of high-strength bolts, and facilitate to install at construction sites.

Analysis of excavation induced stress distributions of GFRP anchors in a soil slope using distributed fiber optic sensors

In this work, a slope reinforcement system using glass fiber reinforced polymer (GFRP) anchors with pressure grouting was adopted in a field project in Hong Kong. The performance of the GFRP anchor during slope excavation was measured using a novel distributed strain sensing technology, known as Brillouin Optic Time Domain Analysis (BOTDA). The full strain profiles along the GFRP anchor under different excavation stages were obtained using specially protected fiber optic sensors. In addition to fiber optic sensors, traditional strain gauges were installed in the same GFRP anchor. Comparisons show that the BOTDA sensors have good accuracy. In addition, the measured results indicate that the maximum tensile strains and forces occurred at one-third of the GFRP anchor length from the slope surface. The tensile force distribution within the active zone is curvilinear which is confirmed by elastic theory analysis. Shear stress distributions along the GFRP anchors were obtained by differentiating the strain data numerically. The theoretical analysis results were consistent with the measured data at the initial excavation stage. However, the theoretical analysis underestimated the shear stress at the final excavation stage where the slope undergoes plastic deformation. Based on the field measurement results and theory analysis, we conclude that the BOTDA sensing technology provides an alternative and effective approach to identifying distributed strains along anchors and shear zones in reinforced slopes.

圧縮部材を用いたケーブルネットワークによる衛星搭載用アンテナの鏡面設計法

Antenna surface forming by cable network is an essential design method to achieve high performance for communication services or high resolution observation for radio astronomy. The precision of the surface can be determined by a facet approximation error depending on their size. Uniform tensile force distribution among cables is measured by adjusting tension ratio of the edge cables and the center cables of the reflector. In general, the tensile forces of the edge cables become several times greater than those of the center cables. Therefore, total strain energy of the cables is decided based on the tensile force distribution including the edge cables. When the number of the cables of the network increases, the total strain energy of the cables raises. Consequently, a support structure, e.g., truss rib structures or hoop structures, must be improved its rigidity to prevent deformation of the surface. This paper describes a new surface forming concept in which the cable network is assembled by tensile and compression members. Several compression members are equipped instead of tensile cables. As a result, the total strain energy of the cables can be reduced, and the retentive force applied to the support structure can also be reduced by using this method.