Banca de DEFESA: JOÃO PAULO DA SILVA COSTA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : JOÃO PAULO DA SILVA COSTA
DATA : 28/08/2017
HORA: 08:00
LOCAL: AUDITÓRIO DO CT
TÍTULO:

Uplift behaviour of helical piles in sand subjected to static and quasi-static cyclic loading.


PALAVRAS-CHAVES:

Helical pile, anchor, pull out load test, numerical modelling, cyclic loading, sand.


PÁGINAS: 110
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
SUBÁREA: Geotécnica
ESPECIALIDADE: Fundações e Escavações
RESUMO:

Helical piles are foundation systems used for supporting compression, tension, and lateral loads. Advantages of helical piles over other foundation systems include fast installation and possibility to apply load immediately. Despite the significant growth around the world in the last 25 years, studies on the behavior of helical piles remain scarce. Field test results in pure sand deposits are particularly needed. In order to fulfil this demand, a field testing program involving helical piles subjected to vertical uplift loads has been conceived. A full-scale prototype of a helical pile with three bearing plates has been designed and built. Seven axial pull out tests with cyclic loading have been performed in a pure sand deposit. Five tests were carried out with static cyclic loading, and included up to 15 load-unload cycles. The other two tests were conducted with quasi-static cyclic loading. The results of the static load tests revealed that soil-pile system stiffness increases after completion of each static loading cycle. Theoretical and empirical methods were used to predict pile ultimate uplift static capacity, and gave conservative predictions as compared to the experimental field test results. The tests with quasi-static loading were carried out with distinct mean cyclic loads and load amplitudes. The results of these tests revealed that increasing mean cyclic load and load amplitude tend to reduce pile stability and soil-pile system stiffness. Soil-pile system static capacity was found to improve after application of quasi-static cyclic loads. Numerical models using the finite element method were developed to evaluate how the behavior of a pile under static loading and embedded in a sandy soil profile is affected by variations in important design parameters, such as helical plate diameter, spacing between helices, and depth of installation. Parametric analysis results gave insight into the distribution of stresses and strains in the soil mass around the pile, and into soil-pile failure mechanisms. According to the investigated conditions, optimum geometrical design parameters for a helical pile include 300 mm diameter plates, depth to diameter ratio of the shallowest helix equal to four, and inter-helix spacing equal to three helix diameters.


MEMBROS DA BANCA:
Presidente - 2551234 - YURI DANIEL JATOBA COSTA
Interno - 1524077 - CARINA MAIA LINS COSTA
Externo à Instituição - CRISTINA DE HOLLANDA CAVALCANTI TSUHA - USP
Notícia cadastrada em: 09/08/2017 09:58
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