scholarly journals Influence of Vetiver Root System on Mechanical Performance of Expansive Soil: Experimental Studies

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guiyao Wang ◽  
Yonggang Huang ◽  
Runfa Li ◽  
Jingmei Chang ◽  
Jinliang Fu
Keyword(s):  
Crack Resistance ◽  
Root System ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Expansive Soil ◽  
Soil Mass ◽  
Expansion Rate ◽  
Grass Roots ◽  
Grass Root ◽  
Swelling Characteristics

In order to study the influence of the vetiver root system on the swelling characteristics and crack resistance of expansive soil, vetiver grass root growth and its vertical distribution were investigated by the cultivation test and observation. The expansion rate experiment without load and expansive force tests was conducted on planted grass root soil samples, and the effect of the root content on the expansion rate and force of soil mass was analyzed. Finally, the effects of different vetiver contents on the crack resistance of expansive soil were studied by soil cracking experiments in an outdoor natural environment. The results showed that on account of the reinforcement effect of crisscrossing and winding grassroots, the expansion rate and expansive force can be reduced by the grass roots, and the grass roots can significantly increase the anticracking properties of the root-soil composites. From the surface down, the inhibition effect of the vetiver root on the expansive soil appeared from low to high and then decreased; the effect was optimal in the layer of 10∼15 cm. Compared with the pure expansive soil, the swelling force of the cultivated root expansive soil growing for 180 d decreased by more than 80%, and the unloaded expansive soil reduced by more than 70%. Compared with pure expansive soil, the swelling force and the unloaded expansion rate of cultivated root expansive soil growing for 90 d decreased by more than 50%.

scholarly journals Computational and experimental mechanical performance of a new everolimus-eluting stent purpose-built for left main interventions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saurabhi Samant ◽  
Wei Wu ◽  
Shijia Zhao ◽  
Behram Khan ◽  
Mohammadali Sharzehee ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Patient Specific ◽  
Wall Structure ◽  
Left Main ◽  
Element Analysis ◽  
Stent Expansion ◽  
Radial Strength ◽  
Different Diameters

AbstractLeft main (LM) coronary artery bifurcation stenting is a challenging topic due to the distinct anatomy and wall structure of LM. In this work, we investigated computationally and experimentally the mechanical performance of a novel everolimus-eluting stent (SYNERGY MEGATRON) purpose-built for interventions to large proximal coronary segments, including LM. MEGATRON stent has been purposefully designed to sustain its structural integrity at higher expansion diameters and to provide optimal lumen coverage. Four patient-specific LM geometries were 3D reconstructed and stented computationally with finite element analysis in a well-validated computational stent simulation platform under different homogeneous and heterogeneous plaque conditions. Four different everolimus-eluting stent designs (9-peak prototype MEGATRON, 10-peak prototype MEGATRON, 12-peak MEGATRON, and SYNERGY) were deployed computationally in all bifurcation geometries at three different diameters (i.e., 3.5, 4.5, and 5.0 mm). The stent designs were also expanded experimentally from 3.5 to 5.0 mm (blind analysis). Stent morphometric and biomechanical indices were calculated in the computational and experimental studies. In the computational studies the 12-peak MEGATRON exhibited significantly greater expansion, better scaffolding, smaller vessel prolapse, and greater radial strength (expressed as normalized hoop force) than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY (p < 0.05). Larger stent expansion diameters had significantly better radial strength and worse scaffolding than smaller stent diameters (p < 0.001). Computational stenting showed comparable scaffolding and radial strength with experimental stenting. 12-peak MEGATRON exhibited better mechanical performance than the 9-peak MEGATRON, 10-peak MEGATRON, or SYNERGY. Patient-specific computational LM stenting simulations can accurately reproduce experimental stent testing, providing an attractive framework for cost- and time-effective stent research and development.

scholarly journals Experimental Study on Mechanical and Sensing Properties of Smart Composite Prestressed Tendon

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2087 ◽  
Author(s):  
Danhui Dan ◽  
Pengfei Jia ◽  
Guoqiang Li ◽  
Po Niu
Keyword(s):  
Stress State ◽  
Carbon Fibers ◽  
Prestressed Concrete ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Tension Force ◽  
Smart Composite ◽  
Steel Wires ◽  
Sensing Performance

It is typically difficult for engineers to detect the tension force of prestressed tendons in concrete structures. In this study, a smart bar is fabricated by embedding a Fiber Bragg Grating (FBG) in conjunction with its communication fiber into a composite bar surrounded by carbon fibers. Subsequently, a smart composite cable is twisted by using six outer steel wires and the smart bar. Given the embedded FBG, the proposed composite cable simultaneously provides two functions, namely withstanding tension force and self-sensing the stress state. It can be potentially used as an alternative to a prestressing reinforcement tendon for prestressed concrete (PC), and thereby provide a solution to detecting the stress state of the prestressing reinforcement tendons during construction and operation. In the study, both the mechanical properties and sensing performance of the proposed composite cable are investigated by experimental studies under different force standing conditions. These conditions are similar to those of ordinary prestressed tendons of a real PC components in service or in a construction stage. The results indicate that the proposed smart composite cable under the action of ultra-high pretension stress exhibits reliable mechanical performance and sensing performance, and can be used as a prestressed tendon in prestressed concrete structures.

Mechanical Behaviour of Steel-Concrete Twin I-Girder Bridges

2018 ◽  
Author(s):  
Weiwei Lin ◽  
Heang Lam ◽  
Teruhiko Yoda
Keyword(s):  
Load Transfer ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Test Results ◽  
Loading Test ◽  
Girder Bridges ◽  
Bridge Model ◽  
Symmetrical Loading ◽  
Unsymmetrical Loading ◽  
Girder Bridge

<p>Steel-concrete composite twin I-girder bridges have been built a lot in both Europe and Japan, but the lack of redundancy has always been a concern in U.S. and many other countries. In addition, few experimental studies have been performed on the mechanical performance of such bridges, particularly for the intact bridges. On this background, a steel-concrete composite twin I-Girder bridge model was designed according to the current highway bridge design specification in Japan and tested in the laboratory. The static loading tests were performed, and two loading conditions including both symmetrical loading and unsymmetrical loading were applied. Load versus deflection relationships were measured in the loading test, and the failure mode of the test specimen was discussed. The flexural strain development on bottom flanges of two main girders was also reported in this paper to confirm the load transfer between two main girders. In addition, the theoretical results on the basis of the classic theory were also provided to compare with the test results. The comparison indicates that the theoretical analyses can predict the behaviour of the twin I-girder bridges very well in the elastic stage by considering the effective width of the slab. The load transfer paths in such bridges were also discussed on the basis of the test results under un-symmetrical loading.</p>

scholarly journals Shear Behaviour of RC Beams Strengthened by Various Ultrahigh Performance Fibre-Reinforced Concrete Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Walid Mansour ◽  
Bassam A. Tayeh
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Element Model ◽  
Shear Behaviour ◽  
Fibre Reinforced Concrete ◽  
Rc Beams ◽  
Shear Span ◽  
Depth Ratio ◽  
Normal Strength

This study presents a numerical investigation on the shear behaviour of shear-strengthened reinforced concrete (RC) beams by using various ultrahigh performance fibre-reinforced concrete (UHPFRC) systems. The proposed 3D finite element model (FEM) was verified by comparing its results with those of experimental studies in the literature. The validated numerical model is used to analyse the crucial parameters, which are mainly related to the design of RC beams and shear-strengthened UHPFRC layers, such as the effect of shear span-to-depth ratio on the shear behaviour of the strengthened or nonstrengthened RC beams and the effect of geometry and length of UHPFRC layers. Moreover, the effect of the UHPFRC layers’ reinforcement ratio and strengthening of one longitudinal vertical face on the mechanical performance of RC beams strengthened in shear with UHPFRC layers is investigated. Results of the analysed beams show that the shear span-to-depth ratio significantly affects the shear behaviour of not only the normal-strength RC beams but also the RC beams strengthened with UHPFRC layers. However, the effect of shear span-to-depth ratio has not been considered in existing design code equations. Consequently, this study suggests two formulas to estimate the shear strength of normal-strength RC beams and UHPFRC-strengthened RC beams considering the effect of the shear span-to-depth ratio.

scholarly journals Fan Ngin Tong Ngin Tjit Jong The Assimilation Face of Grassroot of Chinese Ethnic in Bangka Island, Indonesia

2020 ◽  
Vol 76 ◽  
pp. 01013
Author(s):  
Ibrahim Ibrahim ◽  
Rendy Rendy ◽  
Sujadmi Sujadmi ◽  
Putra Pratama Saputra ◽  
Luna Febriani
Keyword(s):  
Electoral Politics ◽  
Qualitative Approach ◽  
Chinese Identity ◽  
Identity Recognition ◽  
Grass Roots ◽  
The Reformation ◽  
Mining History ◽  
Grass Root ◽  
Long Time ◽  
Grassroots Level

Chinese ethnic in Bangka Island has been there since the colonialism and has become part of tin mining history on the island. It is no wonder that the acculturation has stated for a long time ago especially in the grass root society. This study found out how is Chinese assimilation in this area using the qualitative approach. Based on the data from interviews and observations on the field, the writer found out that Chinese assimilation on the island formed a unity identity without losing their own identity. Tong Ngin Fan Ngin Tjit Tjong which means Chinese and Native, has become the grass roots’ principle and social bond among them. Since the reformation in 1998, this broadens the relation from social into electoral politics. However, the spirit of acculturation in the grass roots must be kept that it doesn’t appear to the surface. The celebration of Chinese identity recognition must be done naturally so as not to cause antipathy. The tolerance that has been practiced so far at the grassroots must be strengthened so that when conflicts of elite interests occur, relations at the grassroots level are not affected.

scholarly journals The effect of bermuda grass root morphology on the displacement of slope

2019 ◽  
Vol 275 ◽  
pp. 03004 ◽  
Author(s):  
Xiao-Lei JI ◽  
Ping YANG
Keyword(s):  
Soil Erosion ◽  
Root System ◽  
Root Morphology ◽  
Bermuda Grass ◽  
Ecological Environment ◽  
Slope Surface ◽  
Organic System ◽  
Geological Disasters ◽  
Grass Root ◽  
Rain Erosion

During recent years, with the drastic development of highway, lots of slopes are produced which cause the increase of geological disasters including soil erosion on the slope and shallow sliding surface, it makes significant impact on the ecological environment. Adopting ecological protection technique of plant slope protection not only can prevent geological disasters, but also benefit the protection of ecological environment. In the paper, bermuda grass, as one kind of ordinary slope protection plants, was chosen as specimen, and the root-soil composite was regarded as organic system which consists of soil and root system; the effect of root morphology on displacement of slope surface under the function of rain erosion and slope runoff erosion was studied and analyzed by using nonlinearity finite calculation method. The result indicates Bermuda grass root system can defense the rain erosion of slope surface soil, restrain the soil displacement and prevent water and soil erosion of slope.

scholarly journals Effectiveness of Root System of Grasses Used in Soil Conservation in Paundi Khola Sub Watershed of Lamjung District, Nepal

1970 ◽  
Vol 2 (1) ◽  
pp. 121-129
Author(s):  
Gandhiv Kafle ◽  
Mohan K Balla
Keyword(s):  
Root System ◽  
Soil Conservation ◽  
Insect Pest ◽  
Relevant Information ◽  
Soil Mass ◽  
Grass Species ◽  
Surface Erosion ◽  
Improved Varieties ◽  
Root Parameters ◽  
Rain Splash

The study was carried out in Paundi Khola Sub-watershed of Lamjung District, with the objective of evaluating the effectiveness of root system of grasses used in soil conservation. Different root parameters were recorded through direct field measurement. Key informant's survey, semi-structured walk and focus group discussions were also undertaken to acquire relevant information on pattern of retaining grasses, insect/pest condition, local uses of grasses, perceived weeds and perception of farmers on different issues. Stylo and Molasses are most effective in armouring the slope against surface erosion from both runoff and rain splash due to their dense surface cover, low canopy and small leaves. Broom Grass and Napier are most effective in reinforcing the soil by providing a network of strong roots that increases the soil's resistance to shear. Broom Grass can moderately support the soil mass by its strong and long fibrous roots. Broom Grass can bind average 3.8 cu. m. soil, and that for napier, stylo, and molasses are 0.37 cu. m., 0.45 cu. m. and 0.04 cu. m. soil respectively. It was found that farmers plant the improved varieties of grasses primarily for forage due to high foliage content. Soil conservation is second priority. A combination of improved varieties of grasses and natural grasses helps to conserve soil and moisture more effectively than single-use of grass species on marginal land. Key Words: Effectiveness, Improved grass species, Root, Soil conservation, Napier, Molasses, Stylo, Broom grass. DOI: 10.3126/init.v2i1.2533 The Initiation Vol.2(1) 2008 pp121-129

scholarly journals Nanostructure and molecular mechanics of spider dragline silk protein assemblies

2010 ◽  
Vol 7 (53) ◽  
pp. 1709-1721 ◽  
Author(s):  
Sinan Keten ◽  
Markus J. Buehler
Keyword(s):  
Secondary Structure ◽  
Spider Silk ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Silk Protein ◽  
Nephila Clavipes ◽  
Protein Assemblies ◽  
Dragline Silk ◽  
Spider Dragline Silk ◽  
Secondary Structure Content

Spider silk is a self-assembling biopolymer that outperforms most known materials in terms of its mechanical performance, despite its underlying weak chemical bonding based on H-bonds. While experimental studies have shown that the molecular structure of silk proteins has a direct influence on the stiffness, toughness and failure strength of silk, no molecular-level analysis of the nanostructure and associated mechanical properties of silk assemblies have been reported. Here, we report atomic-level structures of MaSp1 and MaSp2 proteins from the Nephila clavipes spider dragline silk sequence, obtained using replica exchange molecular dynamics, and subject these structures to mechanical loading for a detailed nanomechanical analysis. The structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly beta-sheet crystal domains, while disorderly regions are formed by glycine-rich repeats that consist of 3 1 -helix type structures and beta-turns. Our structural predictions are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content. Mechanical shearing simulations on selected structures illustrate that the nanoscale behaviour of silk protein assemblies is controlled by the distinctly different secondary structure content and hydrogen bonding in the crystalline and semi-amorphous regions. Both structural and mechanical characterization results show excellent agreement with available experimental evidence. Our findings set the stage for extensive atomistic investigations of silk, which may contribute towards an improved understanding of the source of the strength and toughness of this biological superfibre.

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