Nonlinear dynamic analysis of pile foundation using finite element method

Area of Science:

• Geotechnical Engineering
• Seismology
• Structural Engineering

Background:

• Ethiopia's high seismic risk necessitates robust infrastructure evaluation, particularly for pile foundations.
• Soil-pile-structure interaction is critical for safety and serviceability in seismically active regions like the Afar Triangle.

Purpose of the Study:

• To conduct a nonlinear dynamic response analysis of pile foundations for Bridge B-40 in Ethiopia's seismically active Afar Triangle.
• To evaluate the seismic performance and serviceability of pile foundations under static and dynamic loading conditions.

Main Methods:

• Utilized PLAXIS 3D finite element software incorporating Hardening Soil and Hoek-Brown constitutive models.
• Incorporated site-specific geotechnical and seismic data (PGA = 0.3 g) for static and dynamic simulations.
• Performed free-field site response and free-vibration analyses to determine natural frequencies and seismic amplification.

Main Results:

• Static analysis indicated negligible settlement (0.55 mm) and stresses well below capacity.
• Dynamic analysis revealed pile head displacement of 91.24 mm, within structural limits, but immediate settlement (95.81 mm) exceeded Eurocode serviceability criteria.
• Differential settlements were low (3.5-4.95 mm), and vertical stresses remained below failure limits.

Conclusions:

• Despite adequate stability, the pile foundations exhibit serviceability concerns due to exceeding settlement criteria under seismic loading.
• Nonlinear soil behavior is crucial for accurate pile foundation design in seismic regions.
• The study underscores the need for rigorous evaluation of nonlinear dynamic responses in infrastructure projects within high-risk seismic zones.