Geosynthetic Reinforced Fill Material for Tennessee Bridge Approach Slab Support

The approach slab is constructed at bridge ends to serve as a smooth transition from the highway pavement to the bridge deck. However, motorists usually complain about a sudden change in elevation (bump) at the highway/approach slab (H/S) joint that causes a potential hazard for public safety, damage to vehicles, and rider discomfort. This paper develops a finite element (FE) analysis for the differential settlement at the H/S joint when supported by a strip footing that sits on compacted layers of soil embankment with uniaxial geogrid reinforcement. A parametric study was conducted to select the optimum design that consists of five geogrid layers equally spaced within a depth of 2 [Formula: see text] below the strip footing, where [Formula: see text] is the width of the footing. The inclusion of geogrid reinforcement did not only enhance the ultimate bearing stress of the strip footing but also redistributed the vertical loads over a wider region of soil embankment and thus reduced settlement. A case study is also presented for modeling the performance of a preliminary design proposed by Tennessee Department of Transportation (TDOT) for the retrofit of bridge ends. The FE analysis showed a 30%–40% improvement in the ultimate bearing stress of the strip footing when the geogrid reinforcement proposed by TDOT is extended to a depth of 1.5 [Formula: see text] below the footing.

The use of computational contact mechanics approaches to assess the performance of parts bearing stress concentrators

Purpose: The purpose of this work is to build new computational schemes for assessing the strength parameters of parts with inhomogeneous properties of surface layers in the presence of stress concentrators. Design/methodology/approach: Using the developed approaches of mathematical modeling and open software for calculating the structures of the FEM - FEniCS, the required thickness of the hardened zones of parts has been established, which ensures their minimum softening during operation, depending on the characteristics of the stress concentrator. Findings: It is shown that for each size of the surface stress concentrator there is a critical value of the hardening thickness, the excess of which does not affect the operational strength of the parts, but increases the cost of technological operations. Research limitations/implications: In this article proposes a method for calculating the influence of the dimensional characteristics of hardening zones on the contact strength of parts with stress concentrators under conditions of prevailing power loads. Practical implications: The results obtained in this work were used to determine the technological modes of plasma hardening, which ensure an increase in the contact strength of parts with stress concentrators, depending on their dimensional characteristics. Originality/value: Using the approaches of computational mechanics and mathematical and computer modeling, methods for controlling the contact strength of parts with inhomogeneous non-local properties in the presence of a surface stress concentrator are proposed for the first time.

Conceptual Study of Techno-Stress on Women in Non-IT Sector

Over past few months, teaching and technology experienced a special bond owning to the Covid-19 induced new normal. The use of Information and Communication Technology (ICT) tools in a work-from-home (WFH) scenario though proved prospective for many user/educators. In the hindsight, it has disrupted work-life balance causing counterproductive results. The stakes were high with inadequate training, fund allocation, unidentified strategies, skill deficit and scarce collaborative approaches in the teaching fraternity, further making it quite difficult for an educator to cope-up with sudden challenges to re-invent the teaching trends accordingly. Hence, in this milieu, fast gaining attention is idea of ‘Technostress’. It is conceptually defined as any form of ICT that stimulates stress over the user striving to interact effectively through numerous technological platforms/ gadgets for a substantial span of time. Though past researchers had analyzed it with job satisfaction, employee performance, work load, behavioral stress and aspects of work-family conflict; a special treatment of women educators (in Indian context) undergoing the stress is awaited. In furtherance, education technology with its affinity towards pedagogy, educational policy administrators, technology developers and market are yet to identify women educators need exclusively. Together factors bearing stress under technology-overdrive with strategies to alleviate the same. Now, it is time to reckon women educator’s need, ability, and interest, which should be mapped on optimum and effective use of technology.

Transcuneiform Screw Fixation in Ligamentous Lisfranc Injuries

Category: Trauma; Midfoot/Forefoot Introduction/Purpose: Ligamentous Lisfranc injuries represent a devastating injury complex to the midfoot. Treatment with screw fixation across the first tarsometatarsal (TMT) joint and across the first cuneiform-second metatarsal joint (C1-M2) joint has been described, however there are no studies examining the utility of adding a transcuneiform screw across the first cuneiform-second cuneiform (C1-C2) joint. The purpose of this study was to evaluate the effectiveness of transcuneiform screws at minimizing interosseous displacement in ligamentous Lisfranc injuries when added to traditional Lisfranc screw fixation. Methods: Unstable ligamentous Lisfranc injuries were created on ten fresh-frozen cadaveric specimens by sectioning the interosseous ligaments in a manner that has been described previously. Simulated weight bearing stress (222.4 N) as well as manual abduction and adduction stresses were applied to each specimen and interosseous displacement at the C1-C2 and C1-M2 joints was measured on gross images using calibration with 2mm radiographic marker balls. These measurements were performed initially with no screws, followed by with two-screw fixation across the C1-M2 joint and the first TMT joint, and finally with a third transcuneiform screw across the C1-C2 joint. The images were analyzed and statistical analysis was performed to determine the effect of transcuneiform fixation on interosseous displacement at the C1-C2 and C1-M2 joints. Results: The addition of transcuneiform screw fixation to traditional two-screw fixation decreased the amount of interosseous widening at C1-M2 by an average of 0.03mm at rest, 0.39mm during abduction stress, 0.21mm during adduction stress, and 0.19mm during weight bearing. The interosseous widening at C1-C2 decreased with the addition of transcuneiform fixation by an average of 0.30mm at rest, 0.11mm during abduction stress, 0.18mm during adduction stress, and 0.05mm during weight bearing. Of these findings, only the change in interosseous widening at C1-M2 during abduction stress demonstrated a statistically significant difference (p=0.031) with the addition of the transcuneiform screw compared to traditional two-screw fixation. Conclusion: The addition of transcuneiform screw fixation in ligamentous lisfranc injuries allows less interosseous widening at the C1-M2 joint during abduction stress when compared to traditional two-screw Lisfranc fixation. Further research is required to determine the clinical significance of fixing the transcuneiform joint in Lisfranc injuries and whether or not this potential reduction in motion affects outcomes such as pain control, healing, or function.

On stress *

This chapter explains the difference between syllables with primary stress and syllables which receive secondary or tertiary stress. These notions are relevant because words may consist of many syllables, thereby in principle each offering an equal number of candidates for primary stress. In uninflected words primary stress can fall on any syllable; per word there is a fixed syllable bearing stress, but as soon as inflectional elements kick in, this may change. Many inflectional suffixes attract stress and this gives the general impression that the stress position shifts with every addition, but on the other hand, some word stems with non-final stress retain their primary stress position when inflected. This chapter ends by pointing out that for some words the meaning depends on the stress position.

Numerical simulation on fracturing behaviour of hard roofs at different levels during extra-thick coal seam mining

In fully mechanized caving mining of extra-thick coal seams, the movement range of overburden is wide, resulting in the breakage of multilayer hard roofs in overlying large spaces. However, the characteristics, morphology and impact effect of hard roofs at different levels are different and unclear. In this study, a secondary development was used in the numerical simulation software ABAQUS, and the caving of rock strata in the finite-element software was realized. The bearing stress distribution, fracturing morphology and impact energy characteristics of hard roofs at different levels were studied to reflect the action and difference of hard roof failure on the working face; thus, revealing the mechanism of the strong ground pressure in stopes, and providing a theoretical basis for the safe and efficient mining of extra-thick coal seams with hard roofs.

The modern methods of pin-type bearing test of metallic materials

The special features of various bearing deformation measurements for pin-type bearing tests of metallic materials are considered along with their impact on the magnitude of the «bearing elastic modulus» and bearing stress. These bearing test methods are present in ASTM and various institutional standards, though no state standard (GOST, GOST R) is currently available for bearing test method of metallic materials. Analysis of additional deformations which arise in determining the degree of hole bearing deformation is carried out. A set of sources of additional deformations is shown to be characteristic for each test procedure and is attributed to the design features of the device, the site and a way of mounting the extensometer. Additional deformations can be both tensile and compressive. It is shown that the impact of additional deformations on the «bearing elastic modulus» is limited to 14% for different procedures. No difference between the methods is revealed with regard to determination of the strength characteristics. At the same time the dispersion decreases with increase in plastic deformation and for bearing deformation about 4% the variation coefficient for all methods is no more than 1%. Advantages and shortcomings of the bearing test methods which affect the reproducibility of the results are considered. The effect of the specimen geometry on the bearing characteristics is considered. It is shown that increase both in the distance from the edge of the bearing specimen to the center of the hole for 1163T, VT6ch, 30KhGSA alloys and residual bearing deformation up to 6%, increase bearing strength characteristics.