Abstract:
In reinforced concrete columns, transverse reinforcement is required to provide shear
resistance, restraint against local buckling of longitudinal reinforcement and lateral
confinement to core concrete. However, use of intermediate tie as a transverse
reinforcement is not common. The intermediate ties are the type of transverse rebar that
used to support the non-corner longitudinal reinforcements. Effectiveness of intermediate
tie is affected by parameters such as intermediate tie volumetric ratio, configurations and
tie hook anchorage angles.
The present study numerically investigates the structural behaviour of RC columns that
had various intermediate tie shapes, spacings and hook anchorage angles under constant
axial and lateral loads. Experimental result reported in literature was used for validating
the FE model analysis using ANSYS nonlinear finite element software program. The
columns were modelled as cantilever columns. A total of 53 specimens were modelled
which had a dimension of 550mm by 550mm with span length of 1800mm.
The finite element results of different intermediate tie shapes showed an improvement for
the peak lateral load strength of the columns from 4.18% to 6.08% with regard to
reference column. The ductility of the columns also improved from 5.25% to 22.76%.
This was due to a good lateral restraint provided to longitudinal bars and confinement
pressure for core concrete by the intermidate ties. Increasing the hoop spacing from
100mm to 300mm (that means by 67%) reduced the peak lateral load resistance from
7.33% to 4.02%. The ductility of the columns also decreased from 32.18% to 21.52%.
Increasing the tie hook anchorage angles from 45
o
to 135
o
(that means by 67%) increase
the maximum lateral load resistance of the columns from 0.31% to 2.77% while reduced
the ductility of column by 8.28% (that means from 22.22 to 20.52).
Key words: Hook anchorage angles, Intermediate tie configurations, Spacing, Ductility,
Column failure