A new experimental set-up to study the shear strength of snow-mortar interfaces

2021 ◽  
Author(s):  
Gianmarco Vallero ◽  
Monica Barbero ◽  
Fabrizio Barpi ◽  
Mauro Borri-Brunetto ◽  
Valerio De Biagi
Keyword(s):  
Shear Strength ◽  
Progressive Failure ◽  
Failure Process ◽  
Construction Materials ◽  
Water Film ◽  
Video Camera ◽  
Point Of View ◽  
High Definition ◽  
Snow Layer ◽  
Particle Image Velocimetry Technique

<p>The progressive failure of a snow layer deposited on a stiff substrate is at the base of the comprehension of several physical processes that can be found both in natural and artificial conditions. For instance, glide avalanches often originate from the reduction of the basal friction between the snowpack and the underlying ground due to the presence of liquid water film or depth hoar at the snow-ground interface. Moreover, the interaction between snow and construction materials relates to many other applications such as the study of new and more efficient snow removal techniques, the safety of travelers along snow covered roads, the snow redistribution from roofs and buildings, etc. </p><p>Despite this large number of application fields, laboratory investigations are still limited. We performed cold room tests on artificially made snow-mortar interface specimens through a direct shear test device. The effects of confinement pressure, temperature and dry snow hardness (due to sintering times) were taken into account. The tests were carried out in displacement-controlled conditions in order to study the entire failure process at the interface and the following irreversible sliding. The results show some interesting and encouraging aspects for understanding the shear strength of the interface. From a micromechanical point of view we recorded the tests with a high-definition video camera and analyzed the data with the Particle Image Velocimetry technique to obtain the motion fields on the external side of the specimens. Here, we present and discuss some preliminary results of the experimental activity and suggest some future implementations and further developments of the studied topic.       </p>

Deformation and Rebounding Processes of a Water Droplet Impinging on a Flat Surface Above Leidenfrost Temperature

1996 ◽  
Vol 118 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Hitoshi Fujimoto ◽  
Natsuo Hatta
Keyword(s):  
Surface Tension ◽  
Water Droplet ◽  
Stokes Equations ◽  
Water Film ◽  
Video Camera ◽  
Ring Structure ◽  
Point Of View ◽  
Navier Stokes ◽  
Leidenfrost Temperature ◽  
Incompressible Fluid Flows

This paper treats numerical analyses of the deformation and rebounding processes of a water droplet impinging on a flat solid surface above the Leidenfrost temperature with a speed in the order of a few [m/s], as well as the flow field inside the droplet. These calculations were performed using the MAC-type solution method to solve a finite differencing approximation of the axisymmetric Navier-Stokes equations governing incompressible fluid flows. Also, the whole dynamic process of a droplet from the moment of collision with a hot surface including the rebound from it was recorded by using a video camera equipped with a macro lens. First, the water film formed by the droplet impinging on the surface spreads radially in a fairly thin discoid-like shape until it reaches a maximum. Next, the water film begins to recoil backwards towards the center and the recoiling process continues to occur owing to the surface tension effect at the periphery. Subsequently, the center part of the liquid drop begins to elongate upwards and the liquid near the top of the drop pulls up the lower part of the remaining liquid. Finally, a vortical ring structure appearing at the bottom of the elongated droplet induces the rotative motion in such a way as to form the rising flow and the droplet rebounds from the surface as a bowling pin-shaped mass. The numerical model to predict the deformation and rebounding processes was built up by accounting for the presence of viscous and surface tension effects. The numerical results obtained by the model were compared with the experimental data and discussed from a practical point of view.

scholarly journals Surgeon point-of-view recording: Using a high-definition head-mounted video camera in the operating room

2015 ◽  
Vol 63 (10) ◽  
pp. 771 ◽  
Author(s):  
AkshayGopinathan Nair ◽  
Saurabh Kamal ◽  
TarjaniVivek Dave ◽  
Kapil Mishra ◽  
HarshaS Reddy ◽  
...  
Keyword(s):  
Operating Room ◽  
Video Camera ◽  
Point Of View ◽  
High Definition

scholarly journals Implementation of BIM Modelling and Simulation Tools in Reducing Annual Energy Consumption of Multifamily Dwellings

2020 ◽  
Vol 170 ◽  
pp. 01002
Author(s):  
Subbarao Yarramsetty ◽  
MVN Siva Kumar ◽  
P Anand Raj
Keyword(s):  
Energy Efficient ◽  
Energy Use ◽  
Construction Materials ◽  
Residential Building ◽  
Energy Simulation ◽  
Point Of View ◽  
Rotational Angle ◽  
Existing Building ◽  
Simulation Tools ◽  
Efficient Option

In current research, building modelling and energy simulation tools were used to analyse and estimate the energy use of dwellings in order to reduce the annual energy use in multifamily dwellings. A three-story residential building located in Kabul city was modelled in Revit and all required parameters for running energy simulation were set. A Total of 126 experiments were conducted to estimate annual energy loads of the building. Different combinations from various components such as walls, roofs, floors, doors, and windows were created and simulated. Ultimately, the most energy efficient option in the context of Afghan dwellings was figured out. The building components consist of different locally available construction materials currently used in buildings in Afghanistan. Furthermore, the best energy efficient option was simulated by varying, building orientation in 15-degree increments and glazing area from 10% to 60% to find the most energy efficient combination. It was found that combination No. 48 was best option from energy conservation point of view and 120-degree rotational angle from north to east, of the existing building was the most energy-efficient option. Also, it was observed that 60% glazing area model consumed 24549 kWh more electricity compared to the one with 10% glazing area.

Determination of In-plane Shear Strength of Unidirectional Composite Materials Using the Off-axis Three-point Flexure and Off-axis Tensile Tests

2010 ◽  
Vol 44 (21) ◽  
pp. 2487-2507 ◽  
Author(s):  
G. Vargas ◽  
F. Mujika
Keyword(s):  
Shear Strength ◽  
Composite Materials ◽  
Tensile Tests ◽  
Unidirectional Composite ◽  
Point Of View ◽  
Experimental Point ◽  
Plane Shear ◽  
Lift Off ◽  
Flexure Test

The aim of this work is to compare from an experimental point of view the determination of in-plane shear strength of unidirectional composite materials by means of two off-axis tests: three-point flexure and tensile. In the case of the off-axis three-point flexure test, the condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some considerations regarding stress and displacement fields are presented. The in-plane shear characterization has been performed on a carbon fiber reinforced unidirectional laminate with several fiber orientation angles: 10°, 20°, 30°, and 45°. Test conditions for both off-axis experimental methods, in order to ensure their applicability, are presented. Off-axis flexure test is considered more suitable than off-axis tensile test for the determination of in-plane shear strength.

scholarly journals Thin-film-induced morphological instabilities over calcite surfaces

2015 ◽  
Vol 471 (2176) ◽  
pp. 20150031 ◽  
Author(s):  
R. Vesipa ◽  
C. Camporeale ◽  
L. Ridolfi
Keyword(s):  
Morphological Evolution ◽  
Water Film ◽  
Environmental Parameters ◽  
Climatic Conditions ◽  
Point Of View ◽  
Theoretical Point ◽  
Carbon Dioxide Transport ◽  
Physical Mechanisms ◽  
Water Films ◽  
Dissolved Ions

Precipitation of calcium carbonate from water films generates fascinating calcite morphologies that have attracted scientific interest over past centuries. Nowadays, speleothems are no longer known only for their beauty but they are also recognized to be precious records of past climatic conditions, and research aims to unveil and understand the mechanisms responsible for their morphological evolution. In this paper, we focus on crenulations, a widely observed ripple-like instability of the the calcite–water interface that develops orthogonally to the film flow. We expand a previous work providing new insights about the chemical and physical mechanisms that drive the formation of crenulations. In particular, we demonstrate the marginal role played by carbon dioxide transport in generating crenulation patterns, which are indeed induced by the hydrodynamic response of the free surface of the water film. Furthermore, we investigate the role of different environmental parameters, such as temperature, concentration of dissolved ions and wall slope. We also assess the convective/absolute nature of the crenulation instability. Finally, the possibility of using crenulation wavelength as a proxy of past flows is briefly discussed from a theoretical point of view.

Preparation of Alternative Hydraulic Binder Based on Secondary Raw Materials

2014 ◽  
Vol 1000 ◽  
pp. 12-15
Author(s):  
Jiří Švec ◽  
Tomáš Opravil ◽  
Jiří Másilko
Keyword(s):  
Portland Cement ◽  
Raw Materials ◽  
Construction Materials ◽  
High Volume ◽  
Point Of View ◽  
Hydraulic Lime ◽  
Combustion Gases ◽  
Secondary Raw Materials ◽  
Hydraulic Binder ◽  
Massive Scale

Reusing and recycling of secondary raw materials from high-volume industrial productions (especially form construction materials and binders fabrications) is very important way of conserving environment and it is also interesting from the economical point of view. The production of common hydraulic binders, especially Portland cement, burdens the environment with considerable amount of combustion gases and consumes energy in massive scale. Alternative (low – energy) binder can be used as Portland cement substitution in applications with lower mechanical properties requirements. Mined limestone wash sediments contain large amount of clay components, but there is also indispensable share of fine calcite. This composition makes these sediments a promising material for the preparation of hydraulic binders as Roman cement or hydraulic lime.

Study of the progressive failure of concrete by phase field modeling and experiments

2021 ◽  
pp. 105678952110014
Author(s):  
Jichang Wang ◽  
Xiaoming Guo ◽  
Nailong Zhang
Keyword(s):  
Phase Field ◽  
Progressive Failure ◽  
Failure Process ◽  
Damage Model ◽  
Concrete Fracture ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Edge Notch ◽  
Modeling And Experiments ◽  
Crack Faces

In this research, experiments and numerical simulations are employed to research the failure process of concrete. Fracture experiments on three-point bending (TPB) concrete beams with a prefabricated edge notch at the middle of the beam bottom are performed using a modified rigid testing instrument. The characteristics of the crack and section are analyzed, including the crack tensile opening displacement, crack length and width, and crack faces characteristics. Also, the full curves of the force-crack tensile opening displacement (CMOD) and force-deflection of the TPB beams with the prefabricated edge notch after breakage are obtained. The phase field (PF) damage model is applied to the mixed-mode and mode-I failure processes of concrete structures through the ABAQUS subroutine user defined element (UEL). The crack path and the full curves of force-CMOD and force-deflection obtained by numerical calculations are consistent with the experimental results and the calculated results of other researchers. The influences of the mesh sizes, initial lengths, and notched depths on the TPB beam of concrete are also analyzed.

Demolition Versus Deconstruction: Impacts of Fenestration Disposal in Building Renovation Projects

2014 ◽  
Vol 39 (1) ◽  
pp. 48-55
Author(s):  
Soofia Tahira Elias-Ozkan
Keyword(s):  
Comparative Study ◽  
Construction Materials ◽  
Resource Conservation ◽  
Point Of View ◽  
Similar Construction ◽  
Building Components ◽  
Material Energy

This paper presents findings of a comparative study on the removal and disposal of fenestration units in two separate buildings, belonging to the same period and built with similar construction materials. Demolition techniques were used for removing the fenestration units from a building that was undergoing refurbishment; while, deconstruction techniques were used for dismantling similar units from another building that was being selectively demolished. It was concluded that the amount of energy consumed, time taken and waste generated, were far greater, and the revenues much lower, when conventional demolition techniques and tools were used. Hence, from the point of view of resource conservation (material, energy, time, and money) deconstruction was found to be more advantageous in the disposal of reusable building components.

scholarly journals SELECTION OF WIRELESS TECHNOLOGY FOR TRACKING CONSTRUCTION MATERIALS USING A FUZZY DECISION MODEL / BELAIDŽIO RYŠIO TECHNOLOGIJŲ ATRANKA STATYBINĖMS MEDŽIAGOMS STEBĖTI, TAIKANT NEAPIBRĖŽTŲJŲ AIBIŲ SPRENDIMO MODELĮ

2012 ◽  
Vol 18 (1) ◽  
pp. 43-59 ◽  
Author(s):  
Shaohua Jiang ◽  
Won-Suk Jang ◽  
Mirosław J. Skibniewski
Keyword(s):  
Decision Making ◽  
Construction Projects ◽  
Large Scale ◽  
Construction Materials ◽  
Point Of View ◽  
Wireless Technologies ◽  
Scope Of Application ◽  
Fuzzy Decision Model ◽  
Specific Technology ◽  
Selection Of

As the size and scale of construction projects increase, inefficiencies related to the manual operations about field data in current tracking systems are becoming an important issue. While emerging wireless technologies are providing a feasible vision of ubiquitous computing and sensor networks applicable to the large-scale construction industry, it has become even harder to select a suitable technology for tracking construction materials because of the differing functionalities, capabilities, and scope of application of the specific technology. This research proposes a multi-criteria decision-making model that leverages the decision process in choosing various wireless technologies available on the market. To justify the selection of a specific technology, a fuzzy method was adopted to provide an appropriate way to decide among five alternatives (e.g., RFID, GPS, Wi-Fi, Zigbee, and UWB). Fuzzy ranking was obtained from the aggregated fuzzy appropriate index (FAI) based on a person's point of view (optimist, pessimist, or neutral). The results showed that Wi-Fi might be a suitable solution for optimists and neutral persons, but UWB might be the better alternative for pessimists. The results of this research may assist construction engineers in applying reasonable decision-making procedures in a fuzzy environment such as construction sites, and rank the relative importance of the various criteria and alternatives specified in this research. Santrauka Augant statybos projektų mastui, rankinis dabartinių stebejimo sistemų duomenų apdorojimo neefektyvumas tampa svarbia problema. Nors naujos belaidžio ryšio technologijos gali sudaryti galimybę įvesti visur prieinamus kompiuterinius ir jutiklių tinklus, naudojamus plataus masto statybos pramonėje, tampa vis sudėtingiau pasirinkti tinkamas technologijas statybinėms medžiagoms stebėti, nes kiekviena technologija atlieka skirtingas funkcijas, skiriasi jų galimybės ir taikymo apimtis. Šiame tyrime siūlomas daugiakriterinis sprendimų priėmimo modelis, kuris, sprendimų priėmimo procesą pasirenkant rinkoje, siūlomas belaidžio ryšio technologijas išskaido į atskirus lygius. Siekiant pagrįsti tam tikros technologijos pasirinkimą, buvo pritaikytas neapibrežtųjų aibių metodas, pasirenkant geriausią technologiją iš penkių alternatyvų (t. y. RFID, GPS, Wi-Fi, Zigbee ir UWB technologijų). Neapibrežtumo rangas buvo gautas taikant agreguotą neapibrežtumo tinkamumo indeksą (FAI), atsižvelgiant į asmens požiūrį (optimistinis, pesimistinis ar neutralus). Gauti rezultatai parodė, kad Wi-Fi technologija yra tinkama optimistams ir neutraliems asmenims, o UWB technologija būtų geresnė alternatyva pesimistams. Šio tyrimo rezultatai gali padėti statybos inžinieriams priimti pagrįstus sprendimus neapibrėžtoje aplinkoje, tokioje kaip statybos aikštelės, ir suranguoti pagal svarbą įvairius kriterijus bei aptartas šiame tyrime alternatyvas.

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