scholarly journals Laboratory Testing of Asphalt Belts Rheological Properties Exposed to Shear Loads / Laboratorní Měření Reologických Vlastností Asfaltových Pásů Při Smykovém Zatížení

2012 ◽  
Vol 12 (2) ◽  
pp. 59-66 ◽  
Author(s):  
Martina Janulíková ◽  
Radim Čajka ◽  
Pavlína Matečková ◽  
Vojtěch Buchta
Keyword(s):  
Laboratory Testing ◽  
Environmental Temperature ◽  
Current Knowledge ◽  
Horizontal Load ◽  
Load Effect ◽  
Engineering Research ◽  
Shear Loads ◽  
Sliding Joint ◽  
Sliding Joints ◽  
Load Conditions

Abstract At faculty of civil engineering research is underway which appears with application sliding joints into foundation structures for several years. These sliding joints are applied in order reduce friction from deformation horizontal load effect (effect of undermining or shrinkage and concrete creep and also in prestressed foundation structures in order to allow introduction of prestressing) and they are usually formed from asphalt belts. To better describe the behavior of asphalt belts in sliding joint, it is necessary to know their behavior under the action shear loads over time. For this purpose many laboratory tests are long conducted both for different load conditions (size of the horizontal and vertical loads, the influence of environmental temperature) and different kinds of materials. This paper presents the current knowledge on the basis of measurements carried out so far.

scholarly journals Experimental Measurements of Prestressed Masonry with using Sliding Joint

2014 ◽  
Vol 14 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Marie Stara ◽  
Martina Janulikova
Keyword(s):  
Shear Stress ◽  
Laboratory Testing ◽  
Axial Stress ◽  
Experimental Measurements ◽  
Masonry Structures ◽  
Bottom Part ◽  
Laboratory Equipment ◽  
Sliding Joint ◽  
Anchor Plates ◽  
Sliding Joints

Abstract Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB-Technical University of Ostrava for measurement tri-axial stress-strain conditions in masonry. In this masonry corner two pre-stressing bars are placed. These bars are in different height and are anchored to the anchor plates, which transfer pre-stressing forces to the masonry. The specimen for laboratory testing is performed in the proportion to the reality of 1:1. In the bottom part masonry is inserted asphalt strip. It operates in the masonry like a sliding joint and reduces the shear stress at interface between concrete and masonry structures. The results are compared with the results of masonry without the use of sliding joints, including comment on the effect of sliding joints on the pre-stressing masonry structures.

scholarly journals Influences of Residual Stress, Surface Roughness and Peak-Load on Micro-Cracking: Sensitivity Analysis

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 320
Author(s):  
Jairan Nafar Dastgerdi ◽  
Fariborz Sheibanian ◽  
Heikki Remes ◽  
Hossein Hosseini Toudeshky
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Crack Formation ◽  
Peak Load ◽  
Crack Size ◽  
Effective Parameters ◽  
Load Range ◽  
Load Effect ◽  
Damage Initiation ◽  
Load Conditions

This paper provides further understanding of the peak load effect on micro-crack formation and residual stress relaxation. Comprehensive numerical simulations using the finite element method are applied to simultaneously take into account the effect of the surface roughness and residual stresses on the crack formation in sandblasted S690 high-strength steel surface under peak load conditions. A ductile fracture criterion is introduced for the prediction of damage initiation and evolution. This study specifically investigates the influences of compressive peak load, effective parameters on fracture locus, surface roughness, and residual stress on damage mechanism and formed crack size. The results indicate that under peak load conditions, surface roughness has a far more important influence on micro-crack formation than residual stress. Moreover, it is shown that the effect of peak load range on damage formation and crack size is significantly higher than the influence of residual stress. It is found that the crack size develops exponentially with increasing peak load magnitudes.

Equations for Four-Bar Line-Envelopes

1981 ◽  
Vol 103 (4) ◽  
pp. 743-749 ◽  
Author(s):  
K. H. Hunt ◽  
E. F. Fichter
Keyword(s):  
The Other ◽  
Straight Line ◽  
Sliding Joint ◽  
Line Equation ◽  
Four Bar Linkage ◽  
Sliding Joints

A line-equation (in tangential coordinates) is derived for the envelope of a general straight line attached to the coupler of a planar hinged four-bar linkage. Since a line can be identified with an axis of relative translation parallel to a sliding joint, the study of how lines move in a mechanism has practical potential. Nevertheless the emphasis here is on the geometry of the line-envelopes, and some envelopes are plotted both as samples of what can be obtained and to exemplify some of the properties which they possess. Towards the end of the paper all the other forms of planar four-bar linkage, namely those in which one or two sliding joints replace hinges, are examined, and their envelope-equations are presented.

Design of Bitumen Asphalt Belt Sliding Joint Based on Experiment Results

2017 ◽  
Vol 738 ◽  
pp. 185-194
Author(s):  
Pavlina Matečková ◽  
Martina Smirakova ◽  
Jan Kubosek ◽  
Radim Čajka
Keyword(s):  
Underground Mining ◽  
Fem Analysis ◽  
Shear Resistance ◽  
Test Results ◽  
Horizontal Deformation ◽  
Normal Forces ◽  
Sliding Joint ◽  
Undermined Area ◽  
Sliding Joints ◽  
Foundation Structure

Foundation structures are usually exposed to dominant vertical load. However, in some cases there is also significant value of horizontal load caused e.g. by horizontal terrain deformation on areas attached with underground mining or by horizontal deformation of foundation structure due to pre-stressing, creep, shrinkage, and temperature variation. Through the friction between subsoil and foundations, the foundation structure must resist significant normal forces. The idea of sliding joints between subsoil and foundation structure, which eliminates the friction in footing bottom, comes from the 1970’s. The bitumen asphalt belt given rheological properties has been proven as an effective material for sliding joints. In the paper there are test results of shear resistance of currently used asphalt belts. The test results are used for subsoil shear stress analysis in model example of strip foundation. Shear resistance is calculated according to Czech code for designing buildings on undermined area and also using advanced FEM analysis.

Sliding Joints from Traditional Asphalt Belts

2014 ◽  
Vol 1020 ◽  
pp. 335-340 ◽  
Author(s):  
Martina Smirakova ◽  
Marie Stara ◽  
Petr Mynarčík
Keyword(s):  
Laboratory Test ◽  
Rheological Properties ◽  
Laboratory Tests ◽  
Base Layer ◽  
Horizontal Deformation ◽  
Existing Building ◽  
Sliding Joint ◽  
Different Temperatures ◽  
Correct Function ◽  
Sliding Joints

Problems with horizontal deformation in the subsoil are often solved for building on undermined areas not only in our region. There are many ways to solve this problem. The existing building can be draw together in total or stiffened belt can be carried out around the structure foundation. But the best solution is that which is carried out beforehand. One of the methods which can be applied beforehand is using of sliding joint with using of rheological properties of asphalt. The basic principle of this method lies on application an asphalt belts or another material between foundation and subsoil. It is also created concrete base layer between sliding layer and subsoil to ensure base flatness and to protect of sliding layer material. The type of material is important for correct function of sliding joint and there are very often used the rheological properties of traditional asphalt belts. The laboratory tests are carried out at the Faculty of Civil Engineering VŠB-Technical University of Ostrava to verify their rheological behavior at different loads and different temperatures. Following the test there is the effort to use of obtained values to other calculations and there is effort to contribute to innovation of currently method of design which is based on old materials from the 80th. The principle and the results from the laboratory test as well as current conclusions will be presented in this paper.

scholarly journals Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Ivan Khokhlov ◽  
Mikhail Zertsalov
Keyword(s):  
Numerical Modeling ◽  
Rock Mass ◽  
Bearing Capacity ◽  
Single Unit ◽  
Surrounding Rock ◽  
Design Stage ◽  
Horizontal Load ◽  
Rock Foundation ◽  
Load Effect ◽  
Bored Pile

Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect, as well as loss mechanism of piles bearing capacity, are considered. The article presents the numerical modeling results and a method developed on their basis for calculating piles in rocky soils under the horizontal load effect under the spatial elastic-plastic problem conditions, with the account of the contact behavior between the pile and the rock mass. The study of the single unit bored pile interaction and the surrounding rock mass under the horizontal and moment loads effect was carried out based on the numerical models’ analysis of the piles and the surrounding rock mass in a spatial setting using the finite element method. The use of regression analysis methods made it possible, to obtain parametric equations, based on the numerical modeling obtained results, that connected the studied response functions (bearing capacity and horizontal displacement of the pile) from preselected independent factors reflecting the geomechanical properties of the body and the design piles peculiarities. The developed calculation method allows at the preliminary design stage to estimate the horizontal pile displacement value, as well as its bearing capacity. Also, using the proposed technique, it is possible to make a piles load test schedule, which can be used in the field observation preparation at the design stage. The relevance of the topic is due to the fact that in modern construction practice, bored piles are used to transfer to the foundation significant loads, on the rock foundation from structures for various purposes, including transport (bridges and overpasses piers’ foundations, etc.).

scholarly journals Effects of the Environmental Temperature on Aedes aegypti and Aedes albopictus Mosquitoes: A Review

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 158 ◽  
Author(s):  
Joanna Reinhold ◽  
Claudio Lazzari ◽  
Chloé Lahondère
Keyword(s):  
Climate Change ◽  
Environmental Temperature ◽  
Current Knowledge ◽  
Abiotic Factors ◽  
Potential Effect ◽  
Health Concern ◽  
Factors Affecting ◽  
Host Seeking ◽  
Seeking Behavior ◽  
The Impact

The temperature of the environment is one of the most important abiotic factors affecting the life of insects. As poikilotherms, their body temperature is not constant, and they rely on various strategies to minimize the risk of thermal stress. They have been thus able to colonize a large spectrum of habitats. Mosquitoes, such as Ae. aegypti and Ae. albopictus, vector many pathogens, including dengue, chikungunya, and Zika viruses. The spread of these diseases has become a major global health concern, and it is predicted that climate change will affect the mosquitoes’ distribution, which will allow these insects to bring new pathogens to naïve populations. We synthesize here the current knowledge on the impact of temperature on the mosquito flight activity and host-seeking behavior (1); ecology and dispersion (2); as well as its potential effect on the pathogens themselves and how climate can affect the transmission of some of these pathogens (3).

New Knowledge in the Field of Reduction of Shear Stress in the Foundation Structures of Concrete or Masonry Structures

2014 ◽  
Vol 1082 ◽  
pp. 224-229
Author(s):  
Martina Smirakova
Keyword(s):  
Laboratory Tests ◽  
Mechanical Load ◽  
Thermal Sensitivity ◽  
Masonry Structures ◽  
Horizontal Deformation ◽  
Friction Forces ◽  
Sliding Joint ◽  
Real Behavior ◽  
Sliding Joints ◽  
Foundation Structure

This paper deals with application of sliding joint into foundation structures which can be very helpful in case that the foundation structure is exposed to effect of relative horizontal deformation. These deformations can be created direct in the structure from the effect of creep or shrinkage of concrete, from the effect of pre-stressing of foundation structure or they can arise in the subsoil as a consequence of undermining. Sliding joints are often created from asphalt belts which help to increase of friction forces in the foundation bottom. Due to fact that today ́s market gives a lot of new modern materials, the laboratory tests are carried out to verify their behavior at the Faculty of Civil Engineering VŠB Technical University of Ostrava (Czech Republic). The basic principle of these tests is to simulate real behavior sliding joint in foundation structure and great attention is also focused on thermal sensitivity of majority of used materials. Thermal sensitivity at the action of mechanical load relates closely with their rheological properties. Rheology is the science about deformation of substances in the dependence on time and it helps to describe difficult materials using simpler rheological materials models. A right created rheological model of asphalt belt could be used to prediction of behavior of sliding joint with regard to time of loading and ambient temperature. The knowledge of change of asphalt belt behavior consequently to temperature change could be used in the future to design of this type sliding joint where the temperature will be not only monitored but also managed in the dependence on necessity of increasing or decreasing of shear resistance. Partial results from laboratory tests as well as current conclusion will be presented in this paper.

Load Effects Analysis and Safety Evaluation of High-Pile Pier Slideway Structure while Large Platform Dragged Horizontally to Move to Barge

2014 ◽  
Vol 1065-1069 ◽  
pp. 491-494
Author(s):  
Hong Biao Liu ◽  
Qiang Zhang ◽  
Xian Peng Liu
Keyword(s):  
Bearing Capacity ◽  
Safety Assessment ◽  
Safety Evaluation ◽  
Simulation Method ◽  
Horizontal Load ◽  
Safety Measures ◽  
Load Effect ◽  
Large Platform ◽  
Capacity Calculation ◽  
Load Effects

The bearing capacity calculation in horizontal and safety assessment methods of high-pile pier slideway while large platform dragged horizontally to move to barge was studied based on the theoretic derivation and numerical simulation method. According to the research, the load effect of 6000ton slideway in the process of large platform dragged horizontally is obtained, the safety of slideway is evaluated, and the safety measures of slideway structure which should be taken during dragging platform are recommended. The results of the calculation and analysis show that the bearing capacity of slideway meet the requirements of design under the horizontal load of 11550kN by using uniform force to calculate, and the displacement is less than the width of the structure gap between two segments. The 6000ton sildeway is safe under horizontal load of 11550kN. These conclusions can provide the basis for the safety state analysis of high-pile pier slideway structure and the optimization of plan to move the large platform to load on barge.

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