Energy-efficient solution for the foundation of passive houses in earthquake-prone regions

• Thermal insulation beneath foundations can be used to improve seismic safety.
• Nonlinear dynamic analysis of various realistic regular passive houses.
• Three scenarios: sliding prevention, sliding controllable, sliding isolation system.
• The best solution to reduce structural damage is a sliding isolation system.
• The authors propose controllable sliding, since it can be implemented without extra costs.

In the paper, a new solution is proposed for reducing the seismic response of passive houses founded on layers of thermal insulation (TI) boards which, in such buildings, are usually installed beneath the RC foundations in order to prevent the occurrence of thermal bridges. This could be achieved by allowing controlled lateral sliding to occur along the horizontal surface between the individual layers of the TI boards, as a kind of seismic fuse. Depending on the size of the friction coefficient acting at this surface, three different seismic response scenarios can be foreseen: Scenario 1: Basic protection (“sliding prevention”), Scenario 2: Extended protection (“sliding controllable”), and Scenario 3: Full protection (“sliding isolation system”). Vertical and horizontal restraining elements are also introduced with the aim of preventing extreme lateral shifts or rocking phenomena. The nature of these three seismic response scenarios has been investigated by means of nonlinear dynamic analysis of some simplified parametric models, as well as of some realistic models of two, four and six storeyed RC passive house buildings. The results showed that the total base shear that might act on the superstructure could be reduced by permitting sliding between the layers of TI boards, thus reducing or even preventing the occurrence of damage. In the case of Scenario 2 the proposed seismic fuse could be used in modern energy-efficient houses practically without any additional costs.