Bearing Resistance and Failure Mode of Bolted-layered Cemboard Panels

2020 ◽  
Vol 12 (9) ◽  
Author(s):  
A. F. Norhalim ◽  
◽  
Z. M. Jaini ◽  
Keyword(s):  
Bearing Capacity ◽  
Mixing Process ◽  
Specific Load ◽  
Minimum Thickness ◽  
Bond Slip ◽  
Physical Strength ◽  
Wide Range ◽  
Foamed Concrete ◽  
Floor System ◽  
Bond Mechanism

The fabrication of precast slab can be made from wide range of material either neat concrete, foamed concrete or even composite. Until recently, a new interest has been discovered. Instead of wet concrete mixing process in plant, the precast slab can be substituted with fibre cement board or commonly referred as cemboard that meets the specific load requirements with minimum thickness. However, cemboard panel is preferable for lightweight floor system due to its physical strength limitation. Its thickness that relatively small around 15 mm to 25 mm contribute to the drawback and subsequently prohibited the application of cemboard panel as heavyweight floor system. Small specimens are prepared to determine the optimum orientation of bolts and type of bond by analysing the bearing resistance and bond-slip behaviour. It was found that the bearing capacity is governed by polyurethane glue. Meanwhile, the bond-slip behaviour is effectively controlled by the steel bolt. If the steel bolt is solely used as bond mechanism, the bearing capacity will rely on its quantity and capacity and increasing the quantity of steel bolt will eventually lead to the higher value of bearing resistance.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

Influence of Polypropylene Fiber in Strength of Foamed Concrete

2012 ◽  
Vol 488-489 ◽  
pp. 253-257 ◽  
Author(s):  
Josef Hadipramana ◽  
Abdul Aziz Abdul Samad ◽  
Zi Jun Zhao ◽  
Noridah Mohammad ◽  
W. Wirdawati
Keyword(s):  
Tensile Strength ◽  
Mechanical Test ◽  
Polypropylene Fiber ◽  
High Density ◽  
Splitting Tensile Strength ◽  
Normal Concrete ◽  
Wide Range ◽  
Foamed Concrete ◽  
Strength Result ◽  
And Behavior

Foamed concrete is material that can be used in wide range of constructions and produced in high density. This investigation examined effect of chopped Polypropylene Fiber (PF) that mixed into admixture concerning strength of foamed concrete high density. Mechanical test were performed to measure effect of PF on improving compressive and splitting tensile strength. Result indicate that PF significantly improving compressive strength and behavior of PF where drawn into foamed concrete similarly with normal concrete. The fibrillated PF has been occurred and reduced the micro crack of matrix and prevented propagation crack growth. The presence of PF improved splitting tensile strength was not significantly. Influence of porous of foamed concrete is considered. Scanning Electron Microscope (SEM) exhibits condition microstructure of foamed concrete reinforced PF that alter microstructure, especially interfacial bonding due to PF presence.

Analysis of the Mixing and Emission Characteristics in a Model Combustor

2018 ◽  
Author(s):  
Shan Li ◽  
Shanshan Zhang ◽  
Lingyun Hou ◽  
Zhuyin Ren
Keyword(s):  
Gas Turbines ◽  
Schmidt Number ◽  
Numerical Study ◽  
Flame Temperature ◽  
Scalar Dissipation ◽  
Mixing Process ◽  
Nox Formation ◽  
Turbulent Schmidt Number ◽  
Wide Range ◽  
Air Mixing

Modern gas turbines in power systems employ lean premixed combustion to lower flame temperature and thus achieve low NOx emissions. The fuel/air mixing process and its impacts on emissions are of paramount importance to combustor performance. In this study, the mixing process in a methane-fired model combustor was studied through an integrated experimental and numerical study. The experimental results show that at the dump location, the time-averaged fuel/air unmixedness is less than 10% over a wide range of testing conditions, demonstrating the good mixing performance of the specific premixer on the time-averaged level. A study of the effects of turbulent Schmidt number on the unmixedness prediction shows that for the complex flow field involved, it is challenging for Reynolds-Averaged Navier-Stokes (RANS) simulations with constant turbulent Schmidt number to accurately predict the mixing process throughout the combustor. Further analysis reveals that the production and scalar dissipation are the key physical processes controlling the fuel/air mixing. Finally, the NOx formation in this model combustor was analyzed and modelled through a flamelet-based approach, in which NOx formation is characterized through flame-front NOx and its post-flame formation rate obtained from one-dimensional laminar premixed flames. The effect of fuel/air unmixedness on NOx formation is accounted for through the presumed probability density functions (PDF) of mixture fraction. Results show that the measured NOx in the model combustor are bounded by the model predictions with the fuel/air unmixedness being 3% and 5% of the maximum unmixedness. In the context of RANS, the accuracy in NOx prediction depends on the unmixedness prediction which is sensitive to turbulent Schmidt number.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

Experimental and numerical investigation on the vertical bearing behavior of discrete connected new-type precast reinforced concrete floor system

2020 ◽  
Vol 23 (11) ◽  
pp. 2276-2291
Author(s):  
Rui Pang ◽  
Yibo Zhang ◽  
Longji Dang ◽  
Lanbo Zhang ◽  
Shuting Liang
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cover Plate ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Concrete Floor ◽  
New Type ◽  
Vertical Bearing ◽  
Floor System ◽  
Bearing Behavior

This article proposes a new type of discrete connected precast reinforced concrete diaphragm floor system that consists of precast flat slabs and slab joint connectors. An experimental investigation of discrete connected new-type precast reinforced concrete diaphragm under a vertical distributed static load was conducted, and the effect of slab joint connectors on the load-bearing capacity was evaluated. Then, a finite element analysis of discrete connected new-type precast reinforced concrete diaphragm, precast reinforced concrete floors without slab connectors, and cast-in-situ reinforced concrete floor were performed to understand their working mechanism and determine the differences in load-bearing behavior. The results indicate that the load-bearing capacity and stiffness of discrete connected new-type precast reinforced concrete diaphragm increase considerably as the hairpin and cover plate hybrid slab joint connectors can efficiently connect adjacent precast slabs and enable them to work together under a vertical load by transmitting the shear and moment forces in the orthogonal slab laying direction. The deflection of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction is mainly caused by the opening deformation of the slab joint and the rotational deformation of the precast slabs. This flexural deformation feature can provide reference for establishing the bending stiffness analytical model of discrete connected new-type precast reinforced concrete diaphragm in orthogonal slab laying direction, which is vitally important for foundation of the vertical bearing capacity and deformation calculation method. The deflection and crack distribution patterns infer that the discrete connected new-type precast reinforced concrete diaphragm processes the deformation characteristic of two-way slab floor, which can provide a basis for the theoretical analysis of discrete connected new-type precast reinforced concrete diaphragm.

A Cyclogram of an Energy Efficient Step of a Mobile Robotic System with Wheel-Walking Propulsion

2020 ◽  
pp. 10-16
Author(s):  
M.M. Zhileykin
Keyword(s):  
Energy Efficiency ◽  
Bearing Capacity ◽  
Energy Efficient ◽  
Robotic System ◽  
Mobile Systems ◽  
Robotic Systems ◽  
Wide Range ◽  
Support Surfaces

Mobile robotic systems are employed to perform a wide range of transportation and technological tasks. One of the main requirements to these systems is their high capability to traverse complex terrains and surfaces. Future applications of wheel-walking mobile systems largely define the problem of their energy efficiency. This paper presents a mobile robotic system with wheel-walking propulsion that can increase the system’s traverse capability on support surfaces with low bearing properties due to a new chassis layout and algorithms controlling the walking module. A cyclogram of the energy efficient step of the mobile robotic system with wheel-walking propulsion is developed, which provides high indicators of traverse capability on support bases with low bearing capacity.

Research on Application of Seismic Piezocone Penetration Tests in Pile Foundation

2011 ◽  
Vol 368-373 ◽  
pp. 2722-2730
Author(s):  
Quan Cao ◽  
Hong Chen ◽  
Fa Bo Chen
Keyword(s):  
Bearing Capacity ◽  
Pile Foundation ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Single Pile ◽  
In Situ Tests ◽  
Stress Theory ◽  
Theoretical Relationship ◽  
Wide Range ◽  
Penetration Tests

According to the characteristics of installation about the penetrometer of seismic piezocone penetration tests (SCPTu) and the pile, a theoretical relationship between ultimate bearing capacity of single pile, time-effect of shaft bearing capacity of single pile, excess pore water pressure around the pile during pile driven and the data measured from SCPTu is developed based on the cavity expanded theory, the Terzaghi one-dimensional consolidation theory and effective stress theory. The result of field test in KunShan and the calculated result which used the theoretical relationship mentioned above are compared. The results indicate that the analytical solutions agree well with the in-situ tests, which show that the application of seismic piezocone penetration tests have wide range in the pile foundation.

scholarly journals Cognitive ability and motor performances in the elderly

2020 ◽  
pp. 143-143
Author(s):  
Stevan Jovanovic ◽  
Biljana Stojanovic-Jovanovic ◽  
Aleksandra Pavlovic ◽  
Radovan Milosevic ◽  
Dragan Pavlovic
Keyword(s):  
Physical Fitness ◽  
Executive Functions ◽  
Cognitive Abilities ◽  
Dynamic Balance ◽  
The Elderly ◽  
Upper Body ◽  
Elderly Subjects ◽  
Physical Strength ◽  
Speed Test ◽  
Wide Range

Background/Aim. Ageing entails a wide range of cognitive processes that are not independent of one another. It leads to changes in physical-motor characteristics and sometimes to disability. The aim was to examine the association between multiple cognitive performances in elderly subjects and their physical-motor abilities measured by a variety of tests. Methods: In total, 98 elderly (60+) participants (16 males and 82 females), took part in the study. Cognitive abilities were assessed by the Montreal Cognitive Assessment (MoCA)/Serbian version and physical measures were assessed by the Senior Fitness Test with its five subtests, supplemented by the Walking Speed Test. Results: Several MoCA items demonstrated relatively low variability, i.e. they proved to be too easy for most of the participants. The participants exhibited the lowest performance on the memory relating to other domains, followed by executive functions, visuospatial skills, attention, concentration, and working memory domains, with the highest performance on temporal and spatial orientation relating to other domains. Executive functions and language correlated most significantly with physical strength. Agility and dynamic balance, lower- and upper-body strength, and aerobic endurance correlated moderately and positively. Conclusions: This study underlines the positive correlation between physical fitness and cognitive level in the elderly and emphasizes the importance of physical fitness for cognitive functions, especially those of executive type in elderly subjects. Clinicians should consider the association between cognitive function and physical-motor performances when dealing with functioning improvement in the elderly. The importance of designing the most efficient exercise programs to achieve maximal somatic and cognitive effects.

scholarly journals Experimental and Numerical Investigation of Bond-Slip Behavior of High-Strength Reinforced Concrete at Service Load

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 293
Author(s):  
Alinda Dey ◽  
Domas Valiukas ◽  
Ronaldas Jakubovskis ◽  
Aleksandr Sokolov ◽  
Gintaris Kaklauskas
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Numerical Investigation ◽  
Load Level ◽  
Scale Model ◽  
Element Analysis ◽  
Bond Slip ◽  
Pull Out ◽  
Bond Mechanism ◽  
Concrete Interface

A bond mechanism at the reinforcement-concrete interface is one of the key sources of the comprehensive functioning of reinforced concrete (RC) structures. In order to apprehend the bond mechanism, the study on bond stress and slip relation (henceforth referred as bond-slip) is necessary. On this subject, experimental and numerical investigations were performed on short RC tensile specimens. A double pull-out test with pre-installed electrical strain gauge sensors inside the modified embedded rebar was performed in the experimental part. Numerically, a three dimensional rib scale model was designed and finite element analysis was performed. The compatibility and reliability of the numerical model was verified by comparing its strain result with an experimentally obtained one. Afterwards, based on stress transfer approach, the bond-slip relations were calculated from the extracted strain results. The maximum disparity between experimental and numerical investigation was found as 19.5% in case of strain data and 7% for the bond-slip relation at the highest load level (110 kN). Moreover, the bond-slip curves at different load levels were compared with the bond-slip model established in CEB-fib Model Code 2010 (MC2010). Overall, in the present study, strain monitoring through the experimental tool and finite element modelling have accomplished a broader picture of the bond mechanism at the reinforcement-concrete interface through their bond-slip relationship.

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