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University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnCivil Engineering Theses, Dissertations, andStudent Research Civil Engineering
4-2017
Hyperelastic Structural Fuses for Steel BuildingsFrancys LópezUniversity of Nebraska-Lincoln, [email protected]
Follow this and additional works at: http://digitalcommons.unl.edu/civilengdiss
Part of the Construction Engineering and Management Commons, and the StructuralEngineering Commons
This Article is brought to you for free and open access by the Civil Engineering at DigitalCommons@University of Nebraska - Lincoln. It has beenaccepted for inclusion in Civil Engineering Theses, Dissertations, and Student Research by an authorized administrator ofDigitalCommons@University of Nebraska - Lincoln.
López, Francys, "Hyperelastic Structural Fuses for Steel Buildings" (2017). Civil Engineering Theses, Dissertations, and Student Research.110.http://digitalcommons.unl.edu/civilengdiss/110
Hyperelastic Fuses
Why to upgrade traditional systems? The FEMA P-58-1 listed some of the limitations in present-generation procedures:
Questions regarding the accuracy and reliability of available analytical procedures in predicting actual building response.
“High” level of conservatism underlying the acceptance criteria.
Inability to reliably and economically apply performance-based procedures to the design of new buildings; and
Lack of alternative ways of communicating performance to stakeholders that is more meaningful and useful for decision making purposes.
Performance based design (PBD) emerges as the methodology aiming to bridge this gap, raising the design level performance from life safety (traditional systems) to keep structures fully functional after strong EQ.
What is a traditional Structural Fuse?Structural element where inelastic deformation (damage) is intentionally concentrated.Preferably, disposable and easy to repair structural element.
Remain elastic when subjected to considerably large deformations
Hysteresis Hyperelastic
Why Hyperelasticity?No inelastic deformations, and thus no residual drifts / Resiliency
Fuse initial sketch
Hyperelastic Fuse
The internal elements have an small initial skew that assures that the elements’ buckling path remains through the cycles.
What is a Hyperelastic System?
Target Buildings
How did we address these issues?
The target behavior is represented as follow.
Where: fe = elastic buckling load Ductility = ration between the displacement needed to close the fuse’s gap and the buckling displacement
Alpha1 = ratio between the secondary and initial stiffness
Alpha2 = ratio between the third and initial stiffness
duct ∆= g∆ y
α1 0k= ==2k0
α2 k= 3k0
4
5
Author: Francys López, Graduate Studentfor Steel Buildings
Hyperelastic Structural Fuses
Adviser: Joshua Steelman, Phd.
55
10
4
15
10
Fmax
/fy
9
20
3 8
Fs/fy. .2
.... Tn= 0.05s Sam
=1.6 R=8
Alpha2
25
7
Duct
62
30
541 320 1
8
10
12
14
16
18
20
22
24
26
05
10
4
20
10
Cd
9
30
3 8
Cd. .2
.... Tn= 0.05s Sam
=1.6 R=8
Alpha2
40
7
Duct
62
50
541 320 1
5
10
15
20
25
30
35
40
Building Performance (Under Evaluation)
How does this response (displacement and acceleration)
Using the FEMA P-58 report the respeonse can be associated with fragility levels, which will be useful to compare performance outcomes between strucrures with traditional and hyperelastic fuses.
Conclusions (Under Evaluation)
elastic buckling elements Frame equiped with Hyperelastic Fuses
-5 -4 -3 -2 -1 0 1 2 3 4 5
Sd[in]
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
Fs/w
[k]
Case B Ductility effects with alpha= 0.25
Duct= 1
Duct= 2
Duct= 3
Duct= 4
Duct= 5
Duct= 6
Duct= 7
Duct= 8
Duct= 9
Duct= 10
Duct= 11
Duct= 12
Duct= 13
Duct= 14
Duct= 15
Duct= 16
Duct= 17
Duct= 18
Duct= 19
Duct= 20
Hysteretic
Evaluate hyper elastic fuse potential for retrofitting existing structures.
6 References
R\Tn 0.17 0.356 A B
3.5 C D
It is vital to 3D print fuse samples to investigate geometric sensitivities, and define and analyze the elastic buckling mode (internal elements of the fuse).
FEMA 445 Next Generation Performance- Based Seismic Design Guidelines: Program Plan for New and Existing Buildings. (n.d.). Retrieved February 06,2017, from https://wbdg.org/ffc/dhs/criteria/fema445Goldsworthy, H. (2012). Lessons from the 22 February 2011 Christchurch earthquake. Australian Journal of Structural Engineering, 13(2). doi:10.7158/s11-136.2012.13.2
Parametric Study3Resilient Construction is Needed1
2
1.25
1.4
4
1.6
10
Drif
t [%
]
9
1.8
3 8
Drift. .2
.... Tn= 0.5s Rlim
=3 R=3
Alpha2
2
7
Duct
62
2.2
541 3
20 1
1.4
1.5
1.6
1.7
1.8
1.9
2
X: 8
Y: 3.05
Z: 1.912
05
2
4 10
4
Fmax
/fy
93 8
Fs/fy. .2
.... Tn= 0.5s Sam
=2.9 R=3
6
Alpha2
7
Duct
62
8
541 320 11
2
3
4
5
6
7
X: 2.5
Y: 1.75
Z: 1.534
For 3-story buildings, a ductility higher than 15 is needed to equal the force level on both systems (Hyst. vs Hyper)
translate into performance?