The New Options to Reduce Shear Stress into Foundation Structure

Abstract

This paper deals with analysis of shear stress into foundation structure with applied rheological sliding joint into foundation structures. Rheological sliding joint can create an important part of the building in case that the foundation structure is placed on undermined territory. Buildings which are situated on the edge of settlement trough are often loaded with horizontal deformation from the subsoil. Horizontal deformations then cause shear stress into foundation bottom and tensile forces into foundation. These foundations have to be reinforced a lot or can be structurally modified and can be built on the concrete base layer with rheological sliding joint from different materials. The sliding joint can be created from some different materials but it is often created from asphalt belts. This method was discovered and researched in the 80th at first. Not many materials were on market in this time nevertheless calculation method to determination of shear stress was discovered. Sliding joint was also patented in 1985. Today it was constructed new testing equipment for new tests at the Faculty of Civil Engineering on VŠB – Technical University of Ostrava because the asphalt belts can have very different properties. The testing equipment also allows include effect of ambient temperature. Ambient temperature is monitored because of strong effect on asphalt behavior. The shear response is monitored at the laboratory test and analysis is provided based on results from these experiments. The main objective of this research is to determine calculation method to design sliding into real building. Shear stress into foundation bottom is the most important outcome because from it can be calculated tensile forces and bending moments in foundation structure on which foundation will be assessed. If the settlement trough parameters are known it can be calculated the velocity of deformation in the subsoil. From velocity of subsoil's deformation can be calculated shear stress and also tensile forces and bending moment according to old method and according to Czech standard (ČSN 73 0039 - Building on undermined areas). Calculations are limited to type of applied asphalt belt because the equation for friction's calculation is based on old materials (only two types of oxidized asphalt belts which were in this time on our market). New results and comparison are obtained from new test.