Annual report
Analytical analysis of bridge columns:
UMR structural engineering department is the state-of-the-art facilitator for FE
analysis of structures.
We are familiar with SAP, Abaqus, Ansys, Nastran, Diana, FEAP etc.
For analyzing bridge columns we used DIANA and FEAP.
Model Geometry
Loading
Disk
Shell Region
“Elastic”
Concrete
Core Region
(Transition
Region)
Nonlinear
Transverse
Reinforcement
Concrete
Longitudinal
Reinforcement
(13) RC
Disks
2.5”
24” Dia.
Dia.
Length of the column is 12’-6” from the top of the footing to the centerline of
the applied load. A 2.5” hole in the center of the column cross section was used
to run seven high strength steel strands that were stressed to apply the axial
load.
The load was applied at the top of the column using two hydraulic
actuators in displacement-control mode. The reinforcement consisted of twelve
#8 longitudinal bars, and #3 spiral transverse reinforcement spaced at 2.75”.
1. DIANA Analysis
Analysis with the program DIANA v.9 was conducted for the 3 tested
columns. The model used was similar for all 3 columns, but the applied loads
were different. The model description was presented earlier and consists of 3D
brick elements for the concrete columns and truss elements for both the
longitudinal and transverse bars. The concrete constitutive law followed the
model by xxx with f’c=6 ksi, ε’c=0.002 and εu=0.01; and the steel constitutive law
was elasto-plastic with fy=67 ksi and a hardening ratio of 2%. The column was
assumed fixed at the base and the load was applied through rigid elements
connected to the top of the column.
1.a Pure Bending Specimen (Spc.#1)
Specimen #1 is the control specimen and is tested under uni-axial lateral
loading. The analytical results stopped at the point of ultimate condition (u=10
in.). Good correlation is observed between the analytical and experimental
results.
1.b Pure Torsion Specimen (Spc.#2)
Specimen #2 is tested under pure torsional conditions (i.e. the actuator
forces are equal and in opposite directions). The analytical results stopped at the
o).
Good correlation is observed between the
analytical and experimental results.
1.c Combined loading Specimen (Spc.#3)
Specimen #3 is tested under combined torsion/flexure. Good correlation is
observed between the analytical and experimental results.
2. FEAP Analysis
The finite element program FEAP was installed and developed for twodimensional analysis so far. Extension to include shear deformation is currently
underway. Extension to allow for 3-dimensional analysis necessary to simulate
torsional and combined loading will follow. The program FEAP with fiber beam
elements was used to simulate the behavior of test specimen # 1 under both
monotonic and cyclic loading. The FEAP model successfully described both the
monotonic envelope and the cyclic behavior.
In summary we are able to predict the behavior of column. We figured
several numerical problems and more time consumption with DIANA, so we are
in a process to switching to FEAP.