We want to give a simplified description of the standards to for construction antiseismic, an example with which Italsonda is committed to give customers, a response to any technical and commercial advice to all those activities in which 's resistance is crucial for the peace and security of population of anyone.
The characteristics of the soil must be investigated to a depth significantly. The calculations of stability of complex ground-work and the foundation must be made by the methods of geotechnical, mindful of the forces, the horizontal nature of seismic activity. In particular, it should be followed by the rule indicated european EEC 11/03/88, with special attention to areas in slope, in which the investigation should be extended conveniently outside of the area concerned by the construction.Should also be given special attention to the possibilities that may occur liquefaction of the substrate. The plan of installation should be set to a depth at which there will be no seasonal variation of natural water content of the soil. The coefficient of the foundation and used to calculate the seismic coefficient K is usually assumed equal to 1, but can reach the value of 1.3 because of the degree of compressibility of the soil. The results of investigations are reported in the Report on Foundations, which must necessarily accompany the project at the time, and that should explain assumptions, calculations and graphs.
Work of adjusting the structure of foundation of existing buildings, should strive to achieve levels required for new buildings. Checks are made as required by EEC 11/03/88 reducing the safety factor of 20%. If the tax zone or adjacent slope should be carried out audits of overall slope stability and the building. If it is determined that the substrate may give rise to phenomena of liquefaction, one can not carry out any adjustment without first stabilized the area of intervention with appropriate measures. The action on adaptation on Foundations may be omitted, at the reasoned opinion of the designer and then a geotechnical report, if all the following conditions:
- in not present or have never experienced the phenomena of failure
- intervention not involve substantial alteration of the structure
- intervention does not involve changes in the stresses transmitted to the foundations
- are not rollover to the phenomena of seismic action.