On new 3D FE methodology and verification in EOD Test

Dubravka Mijuca

University UNION – Nikola Tesla, Belgrade

Nina Kordic-Dikovic

VND inženjering i konsalting doo, Belgrade


The linear static and transient dynamic finite element simulation of reinforced precast concrete pile, are performed for the validation and calibration of the new FE methodology. The motive was to develop more user friendly engineering method in order to decrease time and cost of pile installation and control, instead of standard expensive and time consuming static load test measurements of the pile bearing capacity on site. End of Drive Test (EOD Test) is used for the calibration  of the transient dynamic FE simulation, in which history of accelerations of the last full representative blow on the pile, measured by newly wireless designed equipment at point near the top of the pile, is used. The finite elements used are hexahedral eight point elements. The soil constitutive model is Mohr-Coulomb, while drained boundary conditions are assumed in sand. Obtained linear static FE results are two ways validated. Firstly, using the results of static load test measurements, and secondly, using in situ measured acceleration and displacements for validation of the dynamic linear transient analysis results.
Proposed technique makes whole in situ test last no longer that 15 minutes during pile installation, and do not impose delay on work. But most important contribution is in better understanding of dynamic soil-pile-structure interaction based on essential simpler and on experience well- known and understands stress-strain-settlement pile behavior implemented by standard site engineers. Application of this method contributed to make more accurate foundation design, and decreased costs up to 5% less cost for whole bearing structure of buildings at Blok 67a on New Belgrade.

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