Shear and Shear-Friction Strengths of Squat Walls with Flanges

2019 ◽  
Keyword(s):  
Shear Friction ◽  
Squat Walls

scholarly journals Shear Friction Characteristics and Modification Factor of Concrete Prepared Using Expanded Bottom Ash and Dredged Soil Granules

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Keun-Hyeok Yang ◽  
Kyung-Ho Lee
Keyword(s):  
Shear Crack ◽  
Bottom Ash ◽  
Lightweight Aggregate Concrete ◽  
Maximum Aggregate Size ◽  
Crack Plane ◽  
Upper Bound Theorem ◽  
Friction Characteristics ◽  
Dredged Soil ◽  
Shear Friction ◽  
Modification Factor

Abstract The objective of this study is to assess the shear friction characteristics of lightweight aggregate concrete (LWAC) prepared using artificially expanded bottom ash and dredged soil granules. A total of 37 concrete mixtures were prepared under the classification of three series. In the first and second series, the natural sand content for replacing lightweight fine aggregates and the water-to-cement ratio varied to obtain different densities and compressive strengths of concrete. The third series was designed to estimate the effect of the maximum aggregate size on the friction resistance along the shear crack plane of the monolithic interfaces. The frictional angle of the LWAC tested was formulated as a function of the ratio of the effective tensile and compressive strengths of concrete through the expansion of the integrated mathematical models proposed by Kwon et al., based on the upper-bound theorem of concrete plasticity. When predicting the shear friction strength of LWAC, the present mathematical model exhibits relatively good accuracy, yielding the mean and standard deviation of the ratios between experiments and predictions of 1.06 and 0.14, respectively, whereas the empirical equations proposed by the AASHTO provision and Mattock underestimated the results. Ultimately, an advanced modification factor for shear design of LWAC is proposed as a function of the density and compressive strength of concrete and the maximum size of aggregates.

Shear-friction behavior of concrete-to-concrete interface under direct shear load

2021 ◽  
Vol 238 ◽  
pp. 112211
Author(s):  
Jin Xia ◽  
Kuang-yi Shan ◽  
Xiao-hui Wu ◽  
Run-li Gan ◽  
Wei-liang Jin
Keyword(s):  
Shear Load ◽  
Direct Shear ◽  
Friction Behavior ◽  
Shear Friction ◽  
Concrete Interface

scholarly journals Research on the Mechanism of Surfactant Warm Mix Asphalt Additive-Based on Molecular Dynamics Simulation

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1303
Author(s):  
Pinhui Zhao ◽  
Mingliang Dong ◽  
Yansheng Yang ◽  
Jingtao Shi ◽  
Junjie Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Shear Rate ◽  
Asphalt Binder ◽  
Warm Mix Asphalt ◽  
Dynamics Simulation ◽  
Stone Surface ◽  
Lubricating Film ◽  
Lubrication Performance ◽  
Shear Friction

Warm mix asphalt (WMA) technology can bring certain environmental and technical benefits through reducing the temperature of production, paving, and compaction of mixture asphalt. Recent studies have shown that some WMA additives are able to reduce the temperature by increasing the lubricating properties of asphalt binder.-based on the tribological theory, this paper studied the mechanism of adsorbing and lubricating film of base asphalt and WMA on the surface of stone by molecular dynamics (MD) simulation method, and the effect of surfactant WMA additive on the lubrication performance of the shear friction system of “stone–asphalt–stone”. The model of base asphalt lubricating film, including saturates, aromatics, resin and asphaltene, as well as the model of warm mix asphalt lubricating film containing imidazoline-type surfactant WMA (IMDL WMA) additive molecule, were established. The shear friction system of “stone–asphalt–stone” of base asphalt and warm mix asphalt was built on the basis of an asphalt lubrication film model and representative calcite model. The results show that the addition of IMDL WMA additive can effectively improve the lubricity of asphalt, reduce the shear stress of asphalt lubricating film, and increase the stability of asphalt film. The temperature in the WMA lubricating film rises, while the adsorption energy on the stone surface decreases with the increase of shear rate, indicating that the higher the shear rate is, the more unfavorable it is for the WMA lubricating film to wrap on the stone surface. In addition, the shear stress of the WMA lubricating film decreased with increasing temperature, while the shear stress of the base asphalt lubricating film increased first and then decreased, demonstrating that the compactability of the asphalt mixture did not improve linearly with the increase of temperature.

scholarly journals A numerical finite element study on connections of SFRC offshore wind towers with prestressed CFRP reinforcement and steel connectors

2020 ◽  
Vol 5 ◽  
pp. 101-113
Author(s):  
Chandan Gowda ◽  
Fabio P. Figueiredo ◽  
Joaquim A. O. Barros ◽  
António Ventura-Gouveia
Keyword(s):  
Finite Element ◽  
Friction Angle ◽  
Offshore Wind ◽  
Advanced Materials ◽  
Limit States ◽  
Steel Fibre Reinforced Concrete ◽  
Shear Friction ◽  
Nonlinear Features ◽  
Parametric Analyses ◽  
Material Nonlinear

The growing need for sustainable production of electricity highlights the importance and the necessity of having higher number and more effective offshore wind towers. The rapid growth of offshore wind towers is estimated to produce 4% of electricity demands in Europe by the end of 2020. The research described in this paper is part of a project dedicated for the development of innovative structural system using advanced materials for lightweight and durable offshore towers. Specifically, it discusses the nonlinear finite element modelling of the connection between representative prefabricated rings of offshore wind tower made by steel fibre reinforced concrete (SFRC), and prestressed by a hybrid system of carbon fibre reinforced polymers (CFRP) bars and steel strands. This connection is assured by post-tension high steel strength cables and concrete-concrete shear friction width an idealized geometric configuration of the faces in contact. The model takes into account the loads from the rotor, wind and water currents, by considering the critical loading conditions for the safety verifications of serviceability and ultimate limit states. The material nonlinear analyses are carried out with FEMIX V4.0 software, considering a 3D constitutive model capable of simulating the relevant nonlinear features of the SFRC, and interface finite elements for modelling the shear friction of the concrete-concrete surfaces in contact. The parametric analyses involve the influence on the relevant results of the SFRC fracture parameters, pre-stress level of the reinforcements, shape of interlock mechanism, friction angle and interface cohesion.

A Comparison of the Carding and Processing Performance of 2.25 with 1.5-Denier Cotton/Polyester Opening-Room Blends

1976 ◽  
Vol 46 (4) ◽  
pp. 284-290 ◽  
Author(s):  
Jack Simpson ◽  
Louis A. Fiori
Keyword(s):  
High Modulus ◽  
Short Term ◽  
Fiber Properties ◽  
Polyester Fibers ◽  
Shear Friction

Various levels of cotton and polyester fibers blended during opening and picking were investigated to determine their effect on carding efficiency and processing performance. A medium staple cotton of average fiber properties and a high-modulus polyester (2.25 denier) were used in the blends. Shear friction and compression recovery of the blends increased as the percent polyester increased. For the 2.25-den polyester blends, shear friction was slightly lower and compression recovery practically the same as for 1.5-den polyester/cotton blends. Higher polyester content increased friction and cylinder load, thereby reducing carding action so that the short-term sliver variability and neps of the cotton component in the card web increased. Cylinder load and neps in the card web were lower for the 2.25 than the 1.5-den polyester blends. Higher polyester contents slightly improved yarn grade, and the grades for the 2.25-den were higher than those for the 1.5-den polyester blends. Increased friction and length uniformity of the polyester improved drafting so that second-drawing sliver, roving, and yarn uniformity improved when polyester was added to the blend. Carding waste was practically the same whether using 2.25 or 1.5-den polyester; very little polyester was lost in the waste. At constant end breakage, spinning production increased up to a 50/50 blend and then decreased as the percent of 2.25-den polyester was increased. These findings indicate that for cotton and polyester blended in the opening room, one with a high percentage of cotton can be processed more efficiently than the reverse.

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