A Nonlinear Inelastic Numerical Analysis Tool for Circular Concrete-Filled Steel Tubular Columns and BeamColumns
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Date
2019-07
Authors
Journal Title
Journal ISSN
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Publisher
Addis Ababa University
Abstract
The overall objective of this study is to develop fast, simple and accurate numerical
analysis tool to investigate the non-linear inelastic response of circular CFT columns and
beam-columns subjected to eccentric compressive loading. This thesis presents a
systematic development of new numerical models for the nonlinear inelastic analysis of
circular CFT columns and slender beam-columns. In the proposed numerical model, the
inelastic behavior of column cross-sections is simulated using the accurate fiber element
method. Accurate constitutive laws for confined concrete are implemented in the models.
The effects of steel tube local buckling are taken into account in the models. Axial loadmoment-curvature
relationships
computed
from
the
fiber
analysis
of
sections
are
used
in
the
column stability analysis to determine equilibrium states. Efficient computational
algorithms based on Secant’s method are developed to obtain nonlinear solutions.
Analysis procedures are proposed for predicting load-deflection and axial load-moment
interaction curves for circular CFT columns and slender beam-columns under eccentric
compression. The numerical model was used to develop fast, easy and user-friendly MS
Excel spreadsheet analysis tool using visual basic programmed Macros to enhance the
applicability of the study. A total of more than 200 experimental tests of circular
concrete-filled steel tube columns and beam-columns have been used to validate the
developed numerical approach by comparing the maximum load capacity, axial loadaxial
strain/shortening, and axial load- deflection response curves. The developed tool
was utilized to undertake extensive parametric studies on the fundamental behavior of
circular CFT slender columns covering a wide range of parameters. The proposed
numerical approach is capable of tracing the complete circular CFT columns
performance including the challenging post-peak inelastic softening response. Despite
rich features of the proposed numerical scheme, the computational time is highly
efficient and suitable for practical design and analysis of circular concrete-filled steel
tube columns and beam-columns using the tool. Good agreements between the numerical
results with experiments have proved that the proposed numerical scheme is very
efficient for predicting both the maximum load capacity and the axial load - deflection
response of the stub and slender circular concrete-filled steel tube composite columns
and beam-columns. The numerical model analysis has successfully captured the axial
load-strain and axial load-deflection response along with important features.
Description
Keywords
Nonlinear, Inelastic, Numerical, Circular CFT, Confinement, Local Buckling, Slender, Beam-Column, Eccentric Compression