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.

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.

Bitumen Sliding Joints for Friction Elimination in Footing Bottom

2012 ◽  
Vol 188 ◽  
pp. 247-252 ◽  
Author(s):  
Radim Čajka ◽  
Pavlina Matečková ◽  
Martina Smirakova
Keyword(s):  
Underground Mining ◽  
Shear Resistance ◽  
Temperature Deformation ◽  
Horizontal Deformation ◽  
Shrinkage Temperature ◽  
Stress Strain Relation ◽  
Deformation Velocity ◽  
Sliding Joint ◽  
Sliding Joints ◽  
Foundation Structure

Use of a sliding joint is an effective method to decrease the stress in foundation structure where there is a horizontal deformation of subsoil (areas afflicted with underground mining) or horizontal deformation of a foundation structure (pre-stressed foundations, creep, shrinkage, temperature deformation). A convenient material for a sliding joint is a bitumen asphalt belt. Experiments for different types of bitumen belts were undertaken at the Faculty of Civil Engineering - VSB Technical University of Ostrava in 2008. Since 2011 an extension of the 2008 experiments has been in progress and the shear resistance of a slide joint is being tested as a function of temperature in a temperature controlled room. In this paper experimental results of temperature dependant shear resistance are presented. The result of the experiments should be the sliding joint shear resistance as a function of deformation velocity and temperature. This relationship is used for numerical analysis of stress/strain relation between foundation structure and subsoil.

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.

Comparison of the Shear Resistance in the Sliding Joint between Asphalt Belts and Modern PVC Foils

2014 ◽  
Vol 501-504 ◽  
pp. 945-948 ◽  
Author(s):  
Martina Smirakova
Keyword(s):  
Ambient Temperature ◽  
Civil Engineering ◽  
Shear Resistance ◽  
Temperature Dependency ◽  
Horizontal Deformation ◽  
Sliding Joint ◽  
Different Types ◽  
Different Temperatures ◽  
Foundation Structure

This paper deals with sliding joint in the foundation structure. Application of sliding joint into foundation structure is an effective method to reduce effect of horizontal deformation of foundations. These can arise from effect of undermining or from shrinkage or creep of concrete. A different material can be used to create sliding joint but some are advantageous and some are not. It is often used an asphalt belt or newly different modern foils are used too. Different types of asphalt belts are tested at Faculty of Civil Engineering at different loads and at different temperatures. Some foils are tested too. The effect of ambient temperature is monitored to better description of temperature dependency of asphalt belts. Long-term goal of this research is to simplify process of design buildings with sliding joint and to help designer with right choice of the most advantageous material.

scholarly journals Calibration Strategy to Determine the Interaction Properties of Fertilizer Particles Using Two Laboratory Tests and DEM

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 592
Author(s):  
Sugirbay Adilet ◽  
Jian Zhao ◽  
Nukeshev Sayakhat ◽  
Jun Chen ◽  
Zagainov Nikolay ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Laboratory Tests ◽  
Agricultural Research ◽  
Numerical Technique ◽  
Interaction Parameters ◽  
Nonlinear Relationship ◽  
Granular Assemblies ◽  
Real Behavior ◽  
Transient Forces ◽  
Central Composite

Investigating the interactions of granular fertilizers with various types of equipment is an essential part of agricultural research. A numerical technique simulating the mechanical behavior of granular assemblies has the advantage of data trackings, such as the trajectories, velocities, and transient forces of the particles at any stage of the test. The interaction parameters were calibrated to simulate responses of granular fertilizers in EDEM, a discrete element method (DEM) software. Without a proper calibration of the interaction parameters between the granular fertilizers and various materials, the simulations may not represent the real behavior of the granular fertilizers. Therefore, in this study, a strategy is presented to identify and select a set of DEM input parameters of granular fertilizers using the central composite design (CCD) to establish the nonlinear relationship between the dynamic macroscopic granular fertilizer properties and the DEM parameters. The determined interaction properties can be used to simulate granular fertilizers in EDEM.

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.

An Unconventional Method for the Diagnosis and Study of Generator Rotor Thermal Bows

2021 ◽  
Author(s):  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania
Keyword(s):  
Process Parameters ◽  
Regression Models ◽  
Thermal Sensitivity ◽  
Diagnostic Technique ◽  
Diagnostic Techniques ◽  
Linear Regression Models ◽  
Friction Forces ◽  
Winding Insulation ◽  
Multiple Linear Regression Models ◽  
Unconventional Method

Abstract The rotor thermal sensitivity often affects the dynamic behavior of power unit generators. Owing to this phenomenon, increments of field current and other process parameters that are related to it may cause a shaft thermal bow and significant changes in the synchronous vibration. This symptom can also be caused by many other common malfunctions that affect rotating machines. Therefore, diagnostic techniques aimed at identifying the actual fault are very useful for optimizing maintenance activities. The thermal sensitivity of generator rotors can be deemed as a fault because it is commonly caused by a local deterioration of the winding insulation as well as by jamming phenomena between conductors and rotor slots, caused by friction forces due to the different thermal expansions of these components. This paper shows the results obtained applying a diagnostic method, based on multiple linear regression models, which has been developed for the analysis of generator vibrations caused by thermal sensitivity. Nevertheless, nonlinear relationships between vibration and process parameters have also been taken into account. The capabilities of this diagnostic technique have been validated using the analysis of experimental data collected in a power plant. The results of this investigation are shown and discussed in the paper.

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 Volume changes of concrete in interaction with sliding joint

2019 ◽  
Author(s):  
Michal Kropacek ◽  
Radim Cajka ◽  
Petr Mynarcik
Keyword(s):  
Significant Influence ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Outdoor Environment ◽  
Steel Fiber Reinforced Concrete ◽  
Volume Changes ◽  
Comparison Results ◽  
Sliding Joint ◽  
Sliding Joints ◽  
Calculation Models

The paper describes volume changes of cement plain concrete and steel fiber reinforced concrete with strength class C 30/37 in interaction with sliding joints. In the research experiment was performed large-dimensional specimens, on which volume changes were measured using string strain gauges. Below the large-dimensional specimens were designed sliding joints. The specimens were placed in a controlled laboratory environment and in an outdoor environment to simulate real conditions during construction and the measurements were carried out for several months. Volume changes of the concrete were compared to each other and significant influence of the sliding joints was observed. Significant influence on the development of volume changes also has dispersed reinforcement. Another part of the article is a comparison of experimental results with calculation models that allow to calculate the final shrinkage of concrete. Comparison results of volume changes with calculation models is important for demonstrating the effect of sliding joint, as currently valid calculation models do not consider the influence of subsoil and sliding joints, and the results are different as expected. For comparison model B4 (Bazant, 2015), model from technical standard EN 1992-1-1 (CSN EN 1992-1-1, 2006), model from fib model code 2010 (FIB, 2010) and model ACI (ACI, 2008) are used. The paper describes a unique experiment dealing with the influence of sliding joint on the development of volume changes of concrete from beginning of setting and hardening of concrete under precisely defined conditions, that allow comparison with calculation models and thus points to the shortcomings of the building practice.

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