Reologické kluzné spáry s vlivem teplot

Abstract

This dissertation deals with application of rheological sliding joint into foundation structures, with testing of their rheological properties in dependency on temperature and with possible approaches to their design. Rheological sliding joint can create an important part of the building 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 rheological properties of concrete (creep or shrinkage), from the effect of pre-stressing of foundation structure or they can arise in the subsoil as a consequence of undermining. Relative horizontal deformations in the subsoil cause origin of shear stresses on contact surfaces between foundation and subsoil and then tensile (or compressive) loads of concrete structure of foundation. Then we have to reinforce this foundation properly (this often causes too high cost of substructure and too much difficult manufacture). Or we can increase amount of reinforcement significantly, if we use the knowledge from 80th and we apply sliding joint into foundation structure. Rheological sliding joint is often created from an asphalt belt which helps to increase of friction forces in the foundation structure. Due to fact that today´s market gives completely different materials as in the time of original method for increasing friction forces under foundation using sliding joint, it is necessary to verify properties of new materials and their viscous behavior by shear loads using laboratory experiments. 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 (IPA, FOALBIT, BITAGIT etc.). This work follows in dissertation “Foundation structures with sliding joint” - in Czech (Maňásek, 2008) where results of first tests of modern asphalt belts were presented but only at the common ambient temperature. In this work are these tests extended and effect of the ambient temperature is included in laboratory tests. Thermal sensitivity under the action of mechanical load relates closely with their rheological properties. Rheology is the science about deformation of substances in the dependence on time. The basic principle of rheological theory for describing of materials behavior is to compensate real materials using easier materials which are better mathematical and physical describable or using their combinations. Then it is possible to calculate equations for creep and relaxation and relative and constant deformation from known equations. A right created rheological model of asphalt belt can 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.