Prof. Maher Abd El-Rahman Ibrahim Adam :: Publications:

In this study the effect of soft local site on the propagation of seismic waves and on building responses is considered. The seismic waves are generated stochastically based on Japanese seismic design regulation for hard soil condition. When the incident waves propagate from the surrounding hard soil into the building local site, non-linear soil behaviour can occur due to the strong excitation of the local soft soil. For the soft soil the initial relationship between the shear stress and strain proposed by Hardin and Drnevich is used. The hysteresis loops are constructed based on the original Masing’s rules. In the simulation of the propagation of waves to the ground surface the soft local site and the surrounding subsoil are modeled by a finite element method and a boundary element method in the time domain, respectively. The obtained surface ground motions are used as the excitation of the building. For the calculation of the building response the building and the supporting soil are described by a combined finite and boundary element method in the Laplace domain. The investigation reveals that the seismic motions at the ground surface depend not only on the profile of the local soft soil, but also on the degree of the soil ability to behave nonlinearly. The non-linear soft soil causes a reduction of the ground accelerations at all surface locations. The alteration of the ground displacements depends strongly on the considered location. As a consequence of this the activated forces in the building are smaller than the case of a linear soil assumption. The obtained knowledge can be used for an economical design of buildings.