1. The 5th Tongji-UBC Symposium on Earthquake Engineering
“Facing Earthquake Challenges Together” May , Tongji University Shanghai, China
PSEUDO-DYNAMICS HYBRID TESTING OF SIMPLY SUPPORTED HIGH-SPEED RAILWAY BRIDGE SYSTEM
Today, I am
Xu(Ryan) Xie
Research Supervisor: Dr. Tony T.Y. Yang
Co-authors: Tony Yang, Wei Guo, Dorian Tung
BEng | University of British Columbia, Canada (2014)
MASc Student | The University of British Columbia, Canada ( Present)

2. Introduction Operating HSR distance: 16,000 km (350km/hr)
Since 2008, HSR have experienced an unprecedented development and expansion in China
Right now, the distance of the operating HSR with design speed 350 km/hr is more than 16,000 km.
The system cover most of major cities in China. Meanwhile, it go across all major seismic sources in China.

3. Introduction Seismic sources and strong historical earthquake
However, the high speed railway line go through most of the major seismic zones in China.

4. Introduction 58.5% of HSR lines are bridges
90% of the bridges are simply supported bridges
On the other hand, in order to save land and decrease the SSI effect, 58% of the HSR line is built on bridges and 90% of these bridges are belong to this standard type,
Which is precast pre-stressed concrete box girder bridge system
32m and 900 tonnes
That means there are 8000 km of this type of bridge system across the whole country.
However, the seismic performance of this system is unknown. According to the past reconnaissance reports,
it’s vulnerable to earthquake. Then, People proposed a lot of different innovative devices to reduce the seismic risks of this system.

5. Performance-based Earthquake Engineering
Performance-assessment framework (Yang et al, 2009):
Comparing the effectiveness of using innovative technologies for the protection of the HSR bridges
A robust and user-friendly methodology to quantify the seismic risk of structures (OpenSees Navigator)
Problem Statement:
PBEE method is used to quantify the seismic risk of structures and comparing
Today, I will mainly focus on the 2nd step, Response analysis of the this bridge system.

6. Response Analysis Numerical Model - Details Fixed Bearing
Sliding Bearing
Plastic Hinges
- This bridge system is made of three major components: girder, piers and rubber bearing.
During the earthquake, the box girder is usually remain elastic and the plasticity is mainly concentrate in the bearing and the bottom of the piers
So, a numerical model with plastic hinges can be built in OPENSEES.
Pot Rubber Bearing

7. Response Analysis
Cyclic pushover test of 9 typical solid piers (Jiang et al, 2013)
Thanks for Prof. Jiang and his team at CSU, I can easily calibrate the piers bottom hinges with their experimental data.
- This a systematic study on typical solid and hollow piers for HSR has been done at CSU in recent years.

8. Response Analysis Numerical Model in OpenSees Axial Force ( )
2) Horizontal Displacement ( )
3) Rigid Elastic Beam-column-element
4) Hysteretic material for the bottom plastic hinge
Thus, I can simply capture the nonlinearity of the pier by building a

9. Response Analysis Numerical Model – Calibration (OpenSees)
By building a concentr
Hysteresis of Specimen SOL6 and its calibration

10. Response Analysis Pot Rubber Bearing – Hysteretic behaviour
(Chinese design code: GB (2009 edition)
𝐹 𝑚𝑎𝑥 =𝜇 𝑑 ∗𝑁
𝜇 𝑑 =0.02 𝑠𝑙𝑖𝑑𝑖𝑛𝑔 𝑏𝑒𝑎𝑟𝑖𝑛𝑔
𝜇 𝑑 =0.2 𝑓𝑖𝑥𝑒𝑑 𝑏𝑒𝑎𝑟𝑖𝑛𝑔
∆ 𝑦 =2 𝑚𝑚 & ∆ 𝑢 =60 𝑚𝑚
𝑘 𝑒𝑝𝑝 = 𝐹 𝑚𝑎𝑥 / ∆ 𝑦

11. Response Analysis
Numerical Model - Simply supported bridge with three spans in OpenSees
Calibrated rotational plastic hinges are at the bottom of the piers
The hysteretic material of fixed bearings and sliding bearings are assigned to the top of the piers by using separated zero length member
Girder mass and pier mass are scaled down based on the similitude law
Vertical motion of the whole model is restrained.

12. Response Analysis
Numerical Model - Simply supported bridge with three spans in OpenSees
Then we can conduct a experimental test on this bridge.
However, the cost of testing the whole system is too expensive.
Thus, pseudo-dynamic hybrid testing is used in this research.
Calibrated rotational plastic hinges are at the bottom of the piers
The hysteretic material of fixed bearing and sliding bearing are assigned to the top of the piers by using separated zero length member
Girder mass and pier mass are scaled down based on the similitude law
Vertical motion of the whole model is restrained.

13. Hybrid Simulation Test
Hybrid Simulation Test: 2-DOF Model for

14. Hybrid Simulation Test
Equation of motion:
𝑚 1 + 𝑚 2 𝑚 2 𝑚 2 𝑚 𝑢 𝑢 𝑐 𝑐 𝑢 𝑢 𝑘 𝑘 𝑢 1 𝑢 2 =− 𝑚 1 + 𝑚 2 𝑚 2 𝑚 2 𝑚 𝑢 𝑔
Comparison of Period (SOL-6):
OpenSees Model
HS Model
T1 (sec)
0.362
0.162
T2 (sec)
0.3627
0.0907
Damping coefficient:
𝜔 𝑖 𝜔 𝑖 1 𝜔 𝑗 𝜔 𝑗 = 𝑎 0 𝑎 1 = 𝜁 𝑖 𝜁 𝑗

15. Hybrid Simulation Test
HS Model(blue) vs. OpenSees Model (red)
Column response (SOL-6)
Girder response (SOL-6)

16. Ground motion selection
Response Spectrum (Cl GB50111 – 2006)
Chinese code for seismic design of railway engineering
Spectral acceleration =𝑃𝐺𝐴∗β
𝑃𝐺𝐴=0.64𝑔 𝐶𝑙 −1
9th degree seismic resistance
𝑇 𝑔 =0.55 sec 𝐶𝑙 −2 Type III soil with middle R_rupture

17. Ground motion selection
Period Range= [0.01s sec]
23 out of 100: Time steps less than 3500
1 out of 23: The best matched ground motion between period 0.2 and 0.5 sec
PEER Database:
23 out of 100 ground motions
The best matched ground motion between period 0.2 sec and 0.5 sec

18. Potential Failure Mechanism
Column Shear Failure
Column flexural failure
Bridge Unseating Failure (Wenchuan, 2008)

19. Testing Results 100% Ground Motion – Experiment Setup SOL -3 SOL -6
Vertical force on top
Lander ground motion with scaled factor 2.26
SOL -3
SOL -6
SOL -8

20. Testing Results – Hysteresis
100% ground motion – girder unseating failure
1:8 ratio and 1:5 ratio
The bridge will experience girder unseating failure

21. Testing Results 300% ground motion – Pier flexural failure
Cracks from the bottom
SOL-3 (3m – 24m)
SOL-6 (3m – 24m)

22. Testing Results 300% ground motion – Pier shear failure
All three specimen with the same height have the same failure mode. The width of the crack at the bottom is about 1.5 cm.
SOL-8 (1.6m – 8m)

23. Summary
Girder unseating failure is the major risk for the HSR simply support bridge system.
Hybrid simulation test on pot rubber bearings need to be done for further investigating the seismic risk of this bridge system.

24. Thank You!