Evaluation of kinematic bending moments in a pile foundation using the finite element approach

Abstract

During earthquakes seismic waves crossing through soft soil can lead to significant curvatures on pile foundations, which in turn lead to significant bending moments. These bending moments are commonly named "kinematic bending moments" to be distinguished from the "inertial bending moments" due to horizontal forces transferred from superstructures to pile heads. Approaches to carefully evaluate inertial bending moments have been developed worldwide ; on the contrary, up until now different simplified approaches have only led to different evaluations of the kinematic bending moments on pile foundations. Thus, the evaluation of kinematic bending moments is still questionable. Nevertheless, the European technical code EC8 and the new Italian technical code, D.M. 14/01/2008, underline the importance, in the geotechnical and structural design of pile foundations, of taking into account not only inertial bending moments, but also kinematic bending moments, in order to avoid significant structural damage. In this paper a 3D soil-pile FEM system is analysed. The system is subjected to a seismic input motion, applied at the base of the system, which represents the conventional bedrock. The FEM analyses lead to the evaluation of the kinematic bending moment distribution along the pile. Finally, the numerical results are compared with those coming from some simplified approaches available in geotechnical literature.

The Role of Shear Wave Velocity and Non-Linearity of Soil in the Seismic Response of a Coupled Tunnel-Soil-Above Ground Building System

“…The seismic response of the TSS system described in Section 2 was modeled by the ADINA code [31,32], widely used by the authors in dynamic analyses [15,[33][34][35][36][37]. Figure 2 shows the mesh used, including the boundary conditions and the seismic input at the base of the model (bedrock).…”

“…Moreover, the two parallel alignments in which the response of the system was analyzed, one along the symmetry axis of the building and of the tunnel (SS alignment) and another one in free-field conditions (FF alignment), are also represented in Figure 2 as blue lines. The width of the soil deposit was fixed equal to 150 m (>4B, where B is the width of the building), in order to avoid boundary effects as far as possible; the height of the soil deposit derives from geotechnical investigations according to which the bedrock was found at a depth of 38 m. The nodes of the soil vertical boundaries were linked by "constraint equations" that impose the same displacements at the same depth [33,36,[38][39][40]. All the nodes of the base of the mesh were restrained in the vertical direction.…”

Static and Dynamic Properties of Soils in Catania (Italy)

“…Moreover, the following investigations in the laboratory were carried out on undisturbed samples: direct shear tests, triaxial tests, Cyclic Loading Torsional Shear Tests (CLTST) and Resonant Column Tests (RCT). This paper tries to summarize the geotechnical information in a comprehensive way in order to provide a case record of data for site characterization and for the mitigation of seismic risk within structural improvement of buildings [Abate et al, 2016;Abate et al, 2017a;2017b;Grassi and Massimino, 2009]. Similar geotechnical studies were also successful performed for significant historical test sites (Castelli et al 2016a2016f;Cavallaro et al 1999bCavallaro et al , 2003Cavallaro et al , 2004aCavallaro et al , 2004bCavallaro et al , 2013a.…”