Benefits of Concrete Filled Steel Tubes (CFT's)Top
Exceptional strength-to-weight ratio Less strength degradation
than reinforced concrete sections More damping of the structural
response than steel Steel tube provides natural formwork for
pouring concrete Rectangular CFT's can handle biaxial bending
better than steel or reinforced concrete More resistant to fire
than steel sections
Applications of Composite CFT Structural SystemsTop
Three-dimensional static advanced analysis for non-seismic
design Proportion frame to achieve factored loads without reaching
limit point Alleviates need to use AISC LRFD interaction equation
Three-dimensional static "push-over" analysis for seismic design
Three-dimensional nonlinear dynamic analysis for seismic behavioral
evaluation
Research ObjectivesTop
Synopsis - To collect and summarize experimental and
computational research worldwide on CFT's and highlight areas where
more research is warranted Finite Element Formulations - To develop
two finite element formulations, including a concentrated
plasticity "macro" model and a distributed plasticity "fiber"
model, to simulate the behavior of rectangular CFT beam-columns
subjected to monotonic static loading, cyclic static loading, or
transient dynamic loading Performance Based Design - To develop
reliability-based performance-based design guidelines for
rectangular CFT (RCFT) structures
Behavioral Characteristics of RCFT'sTop
The axial force and flexural behavior of RCFT's are summarized
in the following figures:Failure Modes for CFT ColumnsFailure Modes
for CFT Beams
Typical Monotonic Load-Deformation BehaviorResulting Normalized
Cross Section Strength of CFT's
Key Features of Cyclic CFT Behavior Vanishing elastic region
Bauschinger effect Gradual softening Strength degradation Cyclic
hardening Cyclic softening Bounding stiffness
Typical Cyclic CFT BehaviorResulting Concentrated Plasticity
Bounding-Surface Formulation
