Geotechnical and Seismic Engineering
The course aims to introduce students to the basic concepts, theories and analyses in Earthquake Geotechnical Engineering. Because of the vastness of the subject, only some topics are dealt: dynamic characterization of soils, propagation of waves into the ground and the local seismic amplification. In the second part of the course is scheduled teaching a module of Dynamics of Foundations, with the aim of providing students with the tools necessary to take account of factors usually overlooked in the approach of classic design that is learned in other disciplines such as: 1) modification of the seismic signal due to interaction kinematic foundation-soil; 2) the influence of the deformation and energy dissipation capacity of the foundation-soil system on the inertial response of the structure.
Basic knowledge of Soil mechanics
Elements of Seismology.
Seismology and earthquakes. Seismic waves. Movements fault. Duration and intensity of an earthquake. Richter magnitude Moment Magnitude.
Harmonic functions. Trigonometric notation. Amplitude. Frequency. Phase. Algebraic structure of complex numbers. Complex plane and polar coordinates. Complex notation for harmonic functions. Periodic functions. Development in Fourier series. Exponential form or complex notation of the development in series. Complex coefficients. Discrete Fourier transform. Inverse transform.
Dynamics of discrete systems.
Differential equation of the simple oscillator motion. Free and non-damped oscillations. Natural frequency. Oscillation period. Free and damped oscillations. Critical damping. Damping ratio. Factor decay. Forced oscillations and not damped. Resonance. Forced oscillations and damped. Transient and steady state regime. Resonance curves damped systems. Forced oscillations and damped periodically button. Transfer function with exponential notation. Fourier spectrum of amplitudes. Fourier spectrum of the phases. Dirac. Duhamel's integral. Energy dissipated in a hysteresis loop. Viscous damping. Experimental determination of the viscous damping of a system to a degree of freedom. Stiffness complex. Incremental equation of motion. Multi-degree of freedom systems.
Propagation of seismic waves in the ground.
Waves in a medium not confined. One-dimensional waves. Solution of one-dimensional motion. The three-dimensional motion equation for an elastic solid. P waves and S Rayleigh wave. Love wave. Waves in a medium layered. Laws of reflection and transmission at the interface between two layers. Reflection and refraction at the free surface and the bedrock. Absorbent boundaries. Waves inclined. Snell's law. Dissipative effects. Model of Kelvin-Voigt. Propagation of SH waves. Radiation damping.
Characterization of soils under cyclic and dynamic actions
MASW evidence. Cross Hole tests and Dow Hole. Tests SDMT and SCPT. Laboratory tests. Integration with the in situ tests for the determination of the ownership of the land. Try resonant column. Please try bender elements. Cyclic triaxial test, cyclic simple shear (CSS), the torsional shear. Shear modulus at low levels of strain and Secant. Equivalent damping. Decay curves. Plasticity influence. Nonlinear cyclical patterns. Ramberg-Osgood model.
Local Seismic Response Analysis (RSL).
Homogeneous elastic layer on a rigid substrate. Homogeneous elastic layer of deformable substrate. Homogeneous layer of visco-elastic rigid substrate. Homogeneous layer of visco-elastic deformable substrate. Analysis of seismic response in the middle layers. Equivalent linear elastic analysis.
Dynamics of foundations.
Kinematic pile-soil interaction. Bending moments of kinematic interaction at the interface between layers of different stiffness. Analytical methods. Numerical methods. Simplified criteria. Changing the seismic motion at the base of the poles due to the interaction kinematic-ground structure. Changing the seismic motion at the base of a shallow foundation. Changing the seismic motion at the base of the poles due to the interaction kinematic-ground structure. The substructures of the method. Dynamic impedance of shallow foundations. Dynamic Winkler model for the analysis of single pile. Dynamic impedance of pile foundation.
Steven L. Kramer: "Geotechnical Earthquake Engineering" Ed. Prentice Hall, NJ.
Giuseppe Lanzo, Francesco Silvestri: "Analisi di Risposta sismica locale" Ed. Hevelius, Benevento.
Richart, Hall, Woods: "Vibrations of Soils and Foundations". Prentice Hall, NJ.
K. Ishihara: "Soil Behaviour in Earthquake Geotechnics", Clarendon Press.