• 한국조경학회지
• /
• 제31권5호
• /
• pp.1-10
• /
• 2003

The purpose of this study was to verify the shore margin protection effect of a root system developed from direct sticking of Salix gracilistyla Miq., focusing on the reinforcement of soil shear strength. The materials were 20cm long sticks whose average diameter and weight were 7.52mm and 14.58g respectively, and sandy loam(Sand 60.36%, Silt 28%, Clay 11.64%), whose maximum dry weight(${\gamma}$$_{dmax}$) was 1.59gf/㎤ at the water ratio( $W_{opt}$) 13.8%. The direct shearing test(KS F 2343) was applied to cylindric columms(diameter 132mm) of pure soil and two years old root reinforced soil. At each condition of vertical stress, 10N/$ extrm{cm}^2$, 14.41N/$\textrm{cm}^2$ and 18.82 N/$\textrm{cm}^2$, five soil+root columns were sheared. After shear tests, the root area ratio and soil moisture on the shear plane were measured. The results of this research were as follows: 1. The average of root area ratio was 1.86% and the soil moisture 14.67%. 2. Two years old root system was found to increase the soil shear strength of pure soil in terms of Cohesion(C) and Inner friction Angle($\phi$) as follows. 3. The relationship between root area ratio and the increased shear strength can be presented with the following equation, $\Delta$S ≒ 0.33ㆍ TrㆍAs/A $\Delta$S : Increased Shear Strength Tr : Average Tension Strength of Root, Ar/A : Root Area Ratioioage Tension Strength of Root, Ar/A : Root Area Ratio

• Steel and Composite Structures
• /
• 제17권6호
• /
• pp.907-927
• /
• 2014

Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of $1450kg/m^3$ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

• Steel and Composite Structures
• /
• 제42권4호
• /
• pp.553-568
• /
• 2022

This paper explored the viability of utilising titanium alloy bolts in the construction industry through an experimental programme, where a total of sixty-six titanium alloy (Ti/6Al/4V) bolts were tested under axial tension, pure shear and combined tension and shear. In addition, a series of Charpy V-notch specimens machined from titanium alloy bolts, conventional high-strength steel bolts, austenitic and duplex stainless steel bolts were tested for impact toughness comparisons. The obtained experimental results demonstrated that the axial tensile and pure shear capacities of titanium alloy bolts can be reasonably estimated by the current design standards for steel structures (Eurocode 3, AS 4100 and AISC 360). However, under the combined tension and shear loading conditions, significant underestimation by Eurocode 3 and unsafe predictions through AS 4100 and AISC 360 indicate that proper modifications are necessary to facilitate the safe and economic use of titanium alloy bolts. In addition, numerical models were developed to calibrate the fracture parameters of the tested titanium alloy bolts. Furthermore, a design-based selection process of titanium alloy bolts in the structural applications was proposed, in which the ultimate strength, ductility performance and corrosion resistance (including galvanic corrosion) of titanium alloy bolts was mainly considered.

• The Journal of Advanced Prosthodontics
• /
• 제7권1호
• /
• pp.69-75
• /
• 2015

PURPOSE. To compare the shear bond strength of various veneering materials to grade II commercially pure titanium (CP-Ti). MATERIALS AND METHODS. Thirty specimens of CP-Ti disc with 9 mm diameter and 10 mm height were divided into three experimental groups. Each group was bonded to heat-polymerized acrylic resin (Lucitone 199), porcelain (Triceram), and indirect composite (Sinfony) with 7 mm diameter and 2 mm height. For the control group (n=10), Lucitone 199 were applied on type IV gold alloy castings. All samples were thermocycled for 5000 cycles in $5-55^{\circ}C$ water. The maximum shear bond strength (MPa) was measured with a Universal Testing Machine. After the shear bond strength test, the failure mode was assessed with an optic microscope and a scanning electron microscope. Statistical analysis was carried out with a Kruskal-Wallis Test and Mann-Whitney Test. RESULTS. The mean shear bond strength and standard deviations for experimental groups were as follows: Ti-Lucitone 199 ($12.11{\pm}4.44$ MPa); Ti-Triceram ($11.09{\pm}1.66$ MPa); Ti-Sinfony ($4.32{\pm}0.64$ MPa). All of these experimental groups showed lower shear bond strength than the control group ($16.14{\pm}1.89$ MPa). However, there was no statistically significant difference between the Ti-Lucitone 199 group and the control group, and the Ti-Lucitone 199 group and the Ti-Triceram group. Most of the failure patterns in all experimental groups were adhesive failures. CONCLUSION. The shear bond strength of veneering materials such as heat-polymerized acrylic resin, porcelain, and indirect composite to CP-Ti was compatible to that of heatpolymerized acrylic resin to cast gold alloy.

• Computers and Concrete
• /
• 제30권1호
• /
• pp.43-74
• /
• 2022

Machine learning technique is recently opening new opportunities to identify the complex shear transfer mechanisms of reinforced concrete (RC) beam members. This study employed 1224 shear test specimens to train decision tree-based machine learning (ML) programs, by which strong correlations between shear capacity of RC beams and key input parameters were affirmed. In addition, shear contributions of concrete and shear reinforcement (the so-called V_c and V_s) were identified by establishing three independent ML models trained under different strategies with various combinations of datasets. Detailed parametric studies were then conducted by utilizing the well-trained ML models. It appeared that the presence of shear reinforcement can make the predicted shear contribution from concrete in RC beams larger than the pure shear contribution of concrete due to the intervention effect between shear reinforcement and concrete. On the other hand, the size effect also brought a significant impact on the shear contribution of concrete (V_c), whereas, the addition of shear reinforcements can effectively mitigate the size effect. It was also found that concrete tends to be the primary source of shear resistance when shear span-depth ratio a/d<1.0 while shear reinforcements become the primary source of shear resistance when a/d>2.0.

• Structural Engineering and Mechanics
• /
• 제68권3호
• /
• pp.369-375
• /
• 2018

This paper presents the shear buckling analysis of symmetrically laminated cross-ply plates resting on Pasternak foundation under pure in-plane uniform shear load. The classical laminated plate theory is used for the shear buckling analysis of laminated plates. The Rayleigh-Ritz method with novel plate shape functions is proposed to solve the differential equations and a computer programming is developed to obtain the shear buckling loads. Finally, the effects of the plate aspect ratios, boundary conditions, rotational restraint stiffness, translational restraint stiffness, thickness ratios, modulus ratios and foundation parameters on the shear buckling of the laminated plates are investigated.

• 한국정밀공학회지
• /
• 제14권9호
• /
• pp.37-44
• /
• 1997

In this paper the bending collapse characteristics of square and rectangular steel tubes were studied with the pure bending test machine which apply pure bending moment without imposing shear and tensile forces. Under pure bending moment, delayed buckling modes occur and depend on test length and shape of section. For delayed mode, the endrgy of bending moment is absorbed by strain hardening energy. The pre- dictions of maximum moment and moment-rotation angle curve from those concepts are in good agreement with experimental observations.

• Geomechanics and Engineering
• /
• 제12권2호
• /
• pp.211-221
• /
• 2017

A laboratory investigation into crude oil contaminated sand-concrete interface behavior is performed. The interface tests were carried out through a direct shear apparatus. Pure sand and sand-bentonite mixture with different crude oil contents and three concrete surfaces of different textures (smooth, semi-rough, and rough) were examined. The experimental results showed that the concrete surface texture is an effective factor in soil-concrete interface shear strength. The interface shear strength of the rough concrete surface was found higher than smooth and semi-rough concrete surfaces. In addition to the texture, the normal stress and the crude oil content also play important roles in interface shear strength. Moreover, the friction angle decreases with increasing crude oil content due to increase of oil concentration in soil and it increases with increasing interface roughness.

• Structural Engineering and Mechanics
• /
• 제24권2호
• /
• pp.181-194
• /
• 2006

The masonry is a complex heterogeneous material and its shear deformation and fracture is associated with very complicated progressive failures in masonry structure, and is investigated in this paper using a mesoscopic mechanical modelling, Considering the heterogeneity of masonry material, based on the damage mechanics and elastic-brittle theory, the newly developed Material Failure Process Analysis (MFPA) system was brought out to simulate the cracking process of masonry, which was considered as a three-phase composite of the block phase, the mortar phase and the block-mortar interfaces. The crack propagation processes simulated with this model shows good agreement with those of experimental observations by other researchers. This finding indicates that the shear fracture of masonry observed at the macroscopic level is predominantly caused by tensile damage at the mesoscopic level. Some brittle materials are so weak in tension relative to shear that tensile rather than shear fractures are generated in pure shear loading.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.704-709
• /
• 2001

Experimental methods to determine non-linear properties of rubber materials for finite element analysis is discussed. In simple tension tests, dumbbell specimens are generally used to obtain states of pure tension strain. It is shown that the strip specimens of which length is over 10 times of the width can be also used. In simple compression tests, the effect of the friction between the test specimen and the platens is investigated. the new test method with the tapered platen is proposed in order to overcome the effect of friction and it is verified by experimental and finite element analysis results. In pure shear tests, it is shown that the width of the specimen must be at least 10 times of the height. The mechanical conditioning is suggested to stabilize the properties of the rubber materials. Also, engine mount for automotive is analyzed and experimented for each cases.