| dc.description.abstract | At the present only a limited amount of information is
provided by various timber codes and specifications for the
design of built-up timber columns. Very little information
is provided for designing layered timber columns and no
information is given for braced columns. The design method
provided for spaced columns is based on empirical tests and
formulas.
The objective of the present investigation is to develop
a rational procedure for the analysis and design of mechanically connected built-up timber columns including layered,
braced and spaced columns. The theory developed takes into
account the effect of interlayer slip and is applicable to
columns failing in the elastic as well as inelastic ranges of
stress.
The test material is Construction Grade No. 1 .Eastern
Spruce lumber. Connector types used are common wire nails,
steel bolts and split ring connectors. The philosophy and
the procedure presented herein are applicable to other species
of wood as well.
The investigation is conducted in three phases. The
primary aim of phase one is a general theory for predicting
the load-slip behaviour of timber joints subjected to
interlayer slip. Some 250 connections fabricated from three
to seven members and fastened with various types of connectors
are tested. Good agreement is observed between the theory
and the experimental results; the overall average difference
between the two is about five percent. In addition, 2,130
compression tests are conducted to evaluate physical, strength
and elastic properties of the test materials.
Phase two provides a general theory, incorporating the
results of phase one, for predicting the buckling stresses
of built-up timber columns. To verify the theory, a comprehensive test program is conducted on some 400 columns,
including layered, braced and spaced columns of various dimensions built up from two to seven members and covering the
range of slenderness ratio values from thirty-four to one
hundred and fifty. The cross-sections investigated have one
or two axes of symmetry. Statistical techniques are applied
to analyse the test data. Good agreement is observed between
the theoretical predictions and the experimental results.
The overall average difference observed between the predictions and the experimental results is about six and one-half
percent.
Incorporating the results of phases one and two in phase
three, a rational procedure, using dimensionless coefficients
called 'Buckling Coefficients', is developed for the de s ign
of built-up timber columns. This design method is simple
to apply and is applicable to elastic as well as inelastic
columns. | en_US |
