Summary: | A model is presented for the cyclic and dynamic analysis of timber fasteners and pile foundations. Both
systems are, in that they are beam-like structures that are embedded in a flexible medium. In the past, many
different numerical methods, ranging from very elaborate finite element models, to closed-form solutions for
beams on elastic foundations have been used to analyze these systems. Among these, in the development of
computer software, the use of a 1-D finite element implementation of beams on a nonlinear foundation has been
shown to be the most promising, mainly due to the relative accuracy and simplicity of the model. In this thesis,
such a model is developed for the analysis of both systems.
The model is based on one previously developed, which used a beam element on a nonlinear flexible foundation
that takes into account the formation of gaps between the fastener/pile and medium. In this thesis, the effect of
interface friction, and the initial confining pressure surrounding the fastener/pile has been included in the model.
Due to the inclusion of interface friction, the model allows, in the case of piles, the study of problems with
horizontal and/or vertical acceleration inputs. The model is the basis for the development of a cyclic analysis
code for single timber fasteners, and cyclic and dynamic analysis codes for single piles in cohesionless soil.
Various numerical examples of timber fasteners and piles are used to show that the predicted results of the
model are consistent with expected response behavior.
Since previous models have not taken either friction or initial confining pressure into account, the effect of both
of these on the predicted response of both systems has been investigated. It is seen from this study that the
amount of initial confining pressure around a timber fastener does not significantly influence the hysteretic
response under lateral cyclic loading, but rather influences the amount of withdrawal in the case of driven
fasteners. For estimated practical values of the coefficient of friction and tangential stiffness of the interface,
friction is seen to have a significant influence on the amount of withdrawal, and not much influence on the
hysteretic response. In the case of piles, neither the initial confining pressure nor friction are observed to have
any considerable effect on the hysteretic response under lateral cyclic loading === Applied Science, Faculty of === Civil Engineering, Department of === Graduate
|