CastFuse Material

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This command is used to construct a CastFuse uniaxial material. The CastFuse material simulates the hysteretic response a cast yielding fuse (CSF) for concentrically braced frames.

uniaxialMaterial Cast $matTag $n $bo $h $fy $E $L $b $Ro $cR1 $cR2 <$a1 $a2 $a3 $a4>

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$matTag	integer tag identifying material
$n	Number of yield fingers of the CSF-brace
$bo	Width of an individual yielding finger at its base of the CSF-brace
$h	Thickness of an individual yielding finger
$fy	Yield strength of the steel material of the yielding finger
$E	Modulus of elasticity of the steel material of the yielding finger
$L	Height of an individual yielding finger
$b	Strain hardening ratio
$Ro	Parameter that controls the radius after first yielding. Recommended Values $Ro=between 10 to 30
$cR1	Recommended Value $cR1=0.925
$cR2	Recommended Value $cR2=0.150
$a1	isotropic hardening parameter, increase of compression yield envelope as proportion of yield strength after a plastic strain of $a2*($Pp/Kp).
$a2	isotropic hardening parameter (see explanation under $a1). (optional default = 1.0).
$a3	isotropic hardening parameter, increase of tension yield envelope as proportion of yield strength after a plastic strain of $a4*($Pp/Kp).
$a4	isotropic hardening parameter (see explanation under $a3). (optional default = 1.0)

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Examples:

1. Input parameters:

Assume a CSF-Brace with n=10 yielding fingers, bo=250mm, h = 34mm fy=0.365kN/mm2, E=200kN/mm2, L=250mm. In order to calibrate the simulated response of the CSF-brace discussed in [1] and was tested at the University of Toronto the following set of parameters are utilized:

uniaxialMaterial Cast 1 10 250.0 34.0 0.365 200.0 250.0 0.000 19.0 0.925 0.15 0.032 1.0 0.032 1.0

Using these properties a comparison between simulated and experimental response of a CSF brace tested at University of Toronto is shown in Figure 1.

The sensitivity of the viscous damper with respect to its axial stiffness is shown in Figure 2 for the following set of parameters: K=500.0kN/mm, C=100.0kN(s/mm)0.3, a=0.30.

Figure 1. Viscous Damper with K=150.0kN/mm, C=100.0kN(s/mm)0.3, a=0.30

Figure 2. Viscous Damper with K=500.0kN/mm, C=100.0kN(s/mm)0.3, a=0.30

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References:

[1]	Gray, M.G., Christopoulos, C., Packer, J.A., (2010), "Cast Steel Yielding Fuse for Concentrically Braced Frames," Proceedings of the 9th U.S. National and 10th Canadian Conference on Earthquake Engineering, July 25-29, 2010, Toronto, Ontario, Canada, paper No. 595.

Code Developed by : by Dr. Dimitrios G. Lignos, (McGill University)