Illustrating the Modified Non-linear Static Analysis methods to assess the smart structures subjected to intentional blast loading. This study numerically evaluates the robustness of the Nickle Titanium Shape Memory Alloy (NiTi SMA) as smart connection under external blast loading

1. PUSHOVER ANALYSIS
BASED ASSESSMENT
OF SMART
STRUCTURES
SUBJECTED TO
EXTERNAL BLAST
LOADING
Sardasht Sardar Weli és Vigh László Gergely
2019. Augusztus 27
A XIII. MAGYAR MECHANIKAI KONFERENCIA

2. PUSHOVER ANALYSIS BASED
ASSESSMENT OF SMART
STRUCTURES SUBJECTED TO
EXTERNAL BLAST LOADING
Sardasht Sardar Weli1 és Vigh László Gergely2
1Budapesti Műszaki és Gazdaságtudományi Egyetem, Hidak és Szerkezetek Tanszék
1111 Budapest, Műegyetem rkp. 3
serdesht@gmail.com
2 Budapesti Műszaki és Gazdaságtudományi Egyetem, Hidak és Szerkezetek Tanszék
1111 Budapest, Műegyetem rkp. 3
vigh.l.gergely@epito.bme.hu

3. CONTENTS
 Aim of the article
 Introduction
 Technical Steps
 Analytical Model (SDOF)
 Blast Overpressure
 Numerical Models and Analysis
 2D Frame Global Response
 Conclusion
Aim of the article 3

4. AIM OF THE ARTICLE
• Illustrating the Modified Non-linear Static
Analysis methods to assess the smart
structures subjected to intentional blast
loading.
• This study numerically evaluates the
robustness of the Nickle Titanium Shape
Memory Alloy (NiTi SMA) as smart
connection under external blast loading
Introduction 4

5. INTRODUCTION
• The local response of the beam-column connection
was measured and utilized to calculate the global
response of a 2D frame model.
• 2D frame model was subjected to blast overpressure
to evaluate the effect of smart beam-column
connections and investigate the efficiency of the
proposed numerical analysis approach.
• Pushover Analysis based assessment is simple and
efficient tool to evaluate structural performance.
Introduction _ NiTi SMA 5

6. • Nickle Titanium Shape Memory Alloy (NiTi SMA)
bolts were used to connect Beams-to-Columns.
Technical Steps 6
From Hu et al.(2011)• SMA has superiority in
absorbing energy and
recovering structural
deformation.
• It is efficient in mitigating
blast impulses.
• The Martensite Phase transformation of the SMA was
considered in the Numerical Analysis.

7. TECHNICAL STEPS
• OpenSees software was used to generate two different
moment-capacity curves.
• The two moment-capacity curves are converted to
generalized force-deformation relation curves by
FEMA-356 procedures.
• The generalized force-deformation curves are
imported to the numerical analysis by SAP2000 to
measure the global response of the 2D models.
• The global response of the structure was measured by
SAP2000 for the same target displacement for both
NiTi SMA and NS models.
Analytical Model 7

8. ANALYTICAL MODEL (SDOF)
• The concept of virtual work has been applied.
• Generalized SDOF system was employed.
Blast Overpressure 8
𝜔 𝑛
2 =
𝑘
𝑚
=
𝑗=1
𝑁
𝑘𝑗( 𝛹𝑗 − 𝛹𝑗−1
2
𝑗=1
𝑁
𝑚𝑗 𝛹𝑗
2 𝑇𝑛 =
1
𝜔 𝑛
• To validate the numerical Vs. analytical results,
fundamental period of the structure was
calculated and compared which was 0.56sec and
0.62sec for FEA model and the analytical model
respectively.
𝑚 𝑧 + 𝑘𝑧 = 𝑝(𝑡

9. BLAST OVERPRESSURE
Explosive Materials 9
𝐼 = 0.5 𝑃 𝑡 𝑡 𝑑

10. Name of Explosive
Material
TNT
Size (Weight) 50kg
Uncertainties 20%
Standoff Distance 15m
Mean of Transportation Small Size Car
Angle of Incident Not Specified
Phase Positive Phase
Equation Hopkinson-Cranz law
Load Combination 10
𝑍 =
𝑅
𝑊
1
3
• Explosive Material Characteristics
UFC Criteria and JRC T.R

11. Numerical Models and Analysis 11
• The model is
subjected to dead
load, live load, and
snow load plus the
blast overpressure.
𝑊 = 𝐺 𝑘 + 𝐴 𝑑 + 𝛹0 𝑄 𝑘 + 𝛹1 𝑆

12. NUMERICAL MODELS AND ANALYSIS
• OpenSees Model
was created to
generate moment-
rotation curves for
both NiTi SMA and
Normal Steel (NS)
models.
Moment-Capacity curves 12
Models Yield Moment (My)- N.mm Yield Curvature (ϴy) -rad
Ultimate Curvature (ϴu)-rad
NS 215 x 106 0.0077 0.077
SMA 115 x 106 0.1134 0.2134

13. NiTi SMA 13
Sections E (Gpa) Fy (Mpa) Fu (Mpa) A (mm2) Iz (mm4)
Columns (HE-280 E) 21+e4 235 360 9232 1.3 x 108
Beams (IPE 400) 21+e4 235 360 8067 2.2 x 108
• The 2D frame was modeled with HE and
IPE steel sections
0
50
100
150
200
250
300
350
400
450
500
0 0.05 0.1
Moment(N.mm)
Rotation (rad)
NS Ni-Ti SMA
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 2 4 6 8 10 12
Moment
Rotation
NS SMA
FEMA-356OpenSees

14. Joint Classification by Stiffness 14
NITI SMA CONNECTION
• The connection
configuration and
Material were
conventional except the
bolts are SMA.
• The bolts failure were
governing the structural
failure.
• Bolts are the weakest
link in the connection
configuration.

15. JOINT CLASSIFICATION BY STIFFNESS
Target Displacement 15
𝑆𝑗,𝑖𝑛𝑖 =
𝐸𝑍2
𝜇 𝑖
1
𝑘𝑖
Rigid
Semi Rigid
N. Pinned
• En1993.1.8.2005
• EC3-1-8
• Initial Rotational
Stiffness
𝑆𝑗,𝑖𝑛𝑖 ≥
𝑘 𝑏 𝐸𝐼 𝑏
𝐿 𝑏
The joint is Rigid

16. TARGET DISPLACEMENT
Target Displacement 16
0
100000
200000
300000
400000
500000
600000
700000
0 100 200 300 400 500 600
BaseShear(N)
Displacement (mm)
NS SMA
• Pushover analysis
performed to generate
moment-capacity
curve.
• From the equilibrium
of external virtual
work and internal
virtual work. Target
Displacement can be
found.
𝛿𝑊𝐸= 𝛿𝑊𝑙
𝛿𝑊𝐸 =
𝐾𝐿 𝐼 2
2𝐾 𝑚 𝑀
𝛿𝑊𝑙 = 𝐾𝐿
0
𝑥
𝑅 𝑥 𝑑𝑥

17. 2D Frame Global Response _ Shear Forces 17
0
100000
200000
300000
400000
500000
600000
700000
0 50 100 150 200 250 300 350 400
Force(N)
Displacement (mm)
NS
0
50000
100000
150000
200000
250000
300000
350000
400000
0 100 200 300 400 500 600
Force(N)
Dispacemnt (mm)
SMA
160mm
210mm

18. 2D FRAME GLOBAL RESPONSE
2D Frame Global Response _ Axial Forces 18
0
1
2
3
4
5
6
7
8
9
10
18000 38000 58000 78000 98000
Story
Shear Force (N)
NS SMA
13%
~30%
• Shear forces in the
columns

19. 2D FRAME GLOBAL RESPONSE
To Be Concluded 19
0
1
2
3
4
5
6
7
8
9
10
0 200000 400000 600000 800000 1000000
Story
Axial Force (N)
NS SMA
~5%
~4%
• Axial Compression
forces in the columns.

20. TO BE CONCLUDED
• Generalized SDOF along with Pushover Analysis
Based Approach provide reasonable outcomes.
• SMA bolts has noticeable impact on the Shear
forces than the Compression forces.
• SMA bolts has more influence on the lower and
middle column responses than the top columns.
• SMA bolts are very active in dissipating the energy,
therefore the overall structure subjected to lower
forces.
Acknowledgement 20

21. TO BE CONCLUDED
• Although large deformations appeared in the
connection zone, it is feasible, since well-
designed SMA connection behaves nonlinear
elastically and has no residual deformations/no
damages.
21
ACKNOWLEDGEMENT
Support of grant BME FIKP-VÍZ by EMMI is
kindly acknowledged.

22. 22
THANK YOU