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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 96
PROCEEDINGS OF THE THIRTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping and Y. Tsompanakis
Paper 208

Modelling of Foundation Structures with Slide Joints of Temperature Dependant Characteristics

R. Cajka, P. Matecková, M. Janulíková and M. Stará

Department of Building Structures, Faculty of Civil Engineering, VSB Technical University of Ostrava, Czech Republic

Full Bibliographic Reference for this paper
, "Modelling of Foundation Structures with Slide Joints of Temperature Dependant Characteristics", in B.H.V. Topping, Y. Tsompanakis, (Editors), "Proceedings of the Thirteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 208, 2011. doi:10.4203/ccp.96.208
Keywords: foundation structure, sliding joint, bitumen asphalt belt, soil-structure interaction.

Summary
Rheological slide joints are used for elimination of friction, at the bottom of footings, caused by horizontal deformation of the foundation structure owing to shrinkage, creep, pre-stressing and temperature variation or by subsoil deformation, owing to for example undermining. Convenient material for a sliding joint is usually a bitumen asphalt belt. Primary experiments of shear resistance of the bitumen slide joint dates from the 1980s [1].

The material characteristics of the bitumen belt have been changed significantly since that time and this fact demanded new experiments. At VSB - Technical University of Ostrava unique equipment was designed for shear resistance measurement. Renewed experiments for different types of bitumen belts passed in 2008, particular results are presented in [2].

One of the important factors which affect the shear resistance is the temperature and that is the way the experiments continue measuring the shear resistance of the slide joint as a function of temperature in an air-conditioned room. In the paper the first experimental results of the temperature dependant shear resistance are presented, interim test results show that the influence of temperature to shear resistance of the slide joint is significant.

The experiments were carried out so that the results could be used in mathematical modelling of stress-strain conditions in a foundation structure. The results provide the shear stress as a function of relative deformation and time. In the future these will be determined as a function of temperature.

The finite element analysis of the soil-structure interaction demands the determination of subsoil parameters Cz for vertical resistance of subsoil and Cx(Cy) for horizontal resistance of subsoil. In the paper analysis of the friction parameter Cx(Cy) for the foundation structure exposed to horizontal deformation is presented. It is possible to fix the parameter Cx as a constant value for the whole foundation structure. For advanced analysis Cx is treated as a non linear function of the foundation structure coordinates.

Application of the slide joint is an effective strategy to decrease the friction between the deforming structure and subsoil, which enables both material and financial savings.

References
1
V. Balcarek, J. Bradac, "Utilization of bitumen insulating stripes as sliding joints for buildings on undermined area", Civil Engineering, 2, 1982. (in Czech)
2
R. Cajka, P. Manasek, "Laboratory tests and numerical modelling of rheological sliding joints", in Roczniki inSynierii budowlanej - zeszyt, 5, Katowice, Poland, 2005.
3
R. Cajka, "Semispace FEM element and soil - structure interaction", The Third International fib Congress and Exhibition & PCI Annual Convention and Bridge Conference, May 29 - June 2, Washington, D.C., USA, 2010.

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