Abstract: -Among structural damages, seismic induced pounding has been commonly observed in severalearthquakes. When lateral and transverse movement of a structure occurs during earthquakes, it will hit adjacent structure and bounce back. This back and forth hitting of adjacent structures is known as pounding. The earthquake ground motion is usually assumed as uniform dynamic motion in seismic analysis. This assumption may be inadequate for structures placed at large areas like bridge, dam etc. Pounding in bridges is a result of the relative movement of the adjacent bridge superstructures at the expansion joints. This movement depends on different structural dynamic properties of the adjacent spans and characteristics of ground motions at the pier supports along the bridge. This paper includes a study of effect of pounding between bridge superstructures under the action of earthquake motion having multi-support excitation with traveling effect. The present study is a numerical investigation of pounding effect on a simply supported bridge using finite element method, using the software, OpenSees

Alice Mathai

Aswathy Simon

Unni Kartha

CiteSeerX

American Journal of Engineering Research (AJER) 2013 
 
 
Recent Advances in Structural Engineering, RASE2013 Page 29 
American Journal of Engineering Research (AJER) 
e-ISSN : 2320-0847  p-ISSN : 2320-0936 
Volume-4 pp-29-32 
www.ajer.org 
 
Research Paper                                                                                   Open Access 
 
 
Seismic Pounding of Bridges due to Multi-Support Excitation 
with traveling wave 
 
Aswathy Simon
1
, Unni Kartha G
2
 and Alice Mathai
1 
1
Department Of Civil Engineering, Mar Athanasius College Of Engineering, Kerala, India 
2
Department Of Civil Engineering, Federal Institute of Science & Technology, Kerala, India  
 
Abstract: - Among structural damages, seismic induced pounding has been commonly observed in 
severalearthquakes. When lateral and transverse movement of a structure occurs during earthquakes, it will hit 
adjacent structure and bounce back. This back and forth hitting of adjacent structures is known as pounding. The 
earthquake ground motion is usually assumed as uniform dynamic motion in seismic analysis. This assumption 
may be inadequate for structures placed at large areas like bridge, dam etc. Pounding in bridges is a result of the 
relative movement of the adjacent bridge superstructures at the expansion joints. This movement depends on 
different structural dynamic properties of the adjacent spans and characteristics of ground motions at the pier 
supports along the bridge. This paper includes a study of effect of pounding between bridge superstructures 
under the action of earthquake motion having multi-support excitation with traveling effect. The present study is 
a numerical investigation of pounding effect on a simply supported bridge using finite element method, using 
the software, OpenSees. 
 
Keywords:  - Pounding, uniform wave excitation, travelling wave excitation, OpenSees, Random vibration 
method, finite element method. 
 
I. INTRODUCTION  
Pounding is a damage phenomenon resulting from seismic collision in adjacent structures.Generally, 
for seismic analysis the earthquake ground motion is assumed as uniform dynamic motion. But for structures 
placed at large areas, this assumption will not be accurate. Past studies shows that major bridge failures are due 
to the pounding between superstructures. During Northridge earthquake in 1994, severe collision damage 
happened in many piers and expansion joints of No.5 intercontinental highway bridge[1]. During the Kobe 
earthquake in 1995, the collision in bridge made the bearing failure and girder falling. During the Chinese 
Wenchuan earthquake on12th May 2008, the stoppers in Miao Ziping Bridge were broken, which resulted from 
longitudinal and transverse movement and collision and resulted into falling of one span approaching bridge[1]. 
Pounding is a very complicated phenomenon, involves plastic deformations in the materials at the 
location of pounding, energy dissipation during contact etc[2]. For long Multiplan simply supported bridges the 
spatial variation acting at the support should be considered since it can induce pounding effect and deck 
unseating[3]. Recent researches show that these type of bridge structures experiences pounding phenomena 
between adjacent structural segments ie, between neighboring decks or cap beams and decks with a component 
of impact force transferred to the piers. This may lead to differential movement between adjacent spans[4]. For 
such type of bridges to get acceptable approximation we need complex numerical models. 
  In order to study the pounding effect, many researchers have considered uniform dynamic input for 
seismic analysis. But the past earthquake studies shows that for long structures like bridges and dams, the 
assumption of uniform wave excitation is inadequate[5,6]. To get the structural responses including collision by 
mathematical models, many mathematical models were proposed by foreign researchers. There are two methods 
to study collision, collision dynamics method and contact element method. Collision dynamics method uses 
analytical solution technique, so it is difficult for finite element simulation. Contact element method uses 
numerical solution technique, so easy for finite element formulation. So far, there are four collision element 
models are developed. (1) The initial model, the relationship between collision force and deformation is 
American Journal of Engineering Research (AJER) 2013 
 
 
Recent Advances in Structural Engineering, RASE2013 Page 30 
expressed by linear springs, but does not take into account both change of collision and loss of energy.(2) Hertz 
contact model, in which the relationship is expressed by nonlinear springs. (3) Kelvin model, a linear spring 
with a damper is used for the relationship between collision force and deformation. (4) Hertz Damper model, a 
nonlinear relationship between force and deformation including the loss of energy consideration. Some 
researchers found that the Hertz Damper model is the best one for collision elements[7]. MengQingli developed 
the 3D contact friction collision model based on open source software OpenSees, furthermore which was 
realized and validated by numerical simulations of two examples. This collision model can be used on the 
numerical simulation of seismic collision of building and bridge structures. 
 
II. THE ANALYSIS STRUCTURE 
 
Fig. 1 The three span simply supported bridge 
 
The open source software OpenSees is used to model and analyse a simply supported bridge in this 
paper. As shown in Fig. 1, the structure is a reinforced concrete simply supported bridge having overall length 
48.8m and width 8.15m. It has 3 spans in which the two end spans of length n12.2m and mid span of length 
24.4m. The piers of the bridge are columns of diameter 900mm. There are 4 expansion joints over the bridge, 
two of them are steel expansion joints SSFB240, which located on the top of piers of intermediate spans and 
their width is 17cm. The other two are SSFB80, 10cm wide and lie in abutments. 
The finite element model of the bridge is created with open source software OpenSees. While 
modeling, 3D contact friction pounding elements were used in each expansion joint in left and right side in 
longitudinal direction. The longitudinal stiffness and damping of the collision element were K= 3.92x108 N/m 
and Cn = 1.07x107Ns/m, and transverse damping was Ct = 1.07x105Ns/m. The friction coefficient between 
concrete materials was selected as 0.5.Table 1 shows the first three natural periods of the bridge. 
 
Table 1 The first three natural periods of the bridge 
No. Longitudinal Direction Transverse Direction 
1 0.6 1.2 
2 1.1 2.0 
3 1.5 2.4 
 
III. DETERMINATION OF INPUT EARTHQUAKE MOTION 
In the numerical simulation of seismic pounding effect on bridges one typical input ground motion 
isconsidered: Parkfield wave, whose predominant period is larger and closer to the natural period of the bridge. 
The uniform wave excitation and multi-support excitation with travelling effect were considered for the case. 
The characteristic of the earthquake wave is listed in Table 2. 
 
Table 2 The main characteristics of the selected earthquake acceleration motion 
Earthquake Motion Direction Amplitude Predominant Period(s) 
Park Field wave 
E-W 216.5 0.533 
N-S 239.2 0.263 
V 90.0 0.320 
American Journal of Engineering Research (AJER) 2013 
 
 
Recent Advances in Structural Engineering, RASE2013 Page 31 
IV. SEISMIC POUNDING EFFECT ANALYSIS OF THE BRIDGE 
For the study of seismic pounding effect on the bridge, the analysis was carried out under uniform seismic 
excitations and multi-support excitation with travelling effect. Throughout the paper “Uniform” denotes uniform 
seismic excitations and “Traveling” denotes multi-support excitation with travelling effect. 
 
V. CONTACT FRICTION POUNDING RESPONSE 
Table 3 shows the number of pounding at different locations of the bridge under uniform and travelling waves. 
By comparing the pounding number we can see that numberof pounding is smaller under travelling effect, and 
intermediate supports. 
 
Table 3 The number of Pounding 
LOCATION 
Left abutment Left inte.pier Right inte.pier Right abutment 
Left  Right  Left  Right  Left  Right  Left  Right  
Uniform 5 5 6 6 6 7 3 2 
Traveling 2 4 2 3 5 6 3 2 
 
From Table 4 it is clear that, the pounding force is more for travelling effect as compared touniform excitation. 
At middle spans, the pounding force is more like number of pounding, whichshows that the intermediate 
supports are the peak pounding points. 
 
Table 4 Peak pounding force (x 10
7
 N) 
LOCATION 
Left abutment Left inte.pier Right inte.pier Right abutment 
Left  Right  Left  Right  Left  Right  Left  Right  
Uniform 0.60(6) 0.23(5s) 0.57(6) 0.63(6s) 1.10(5) 1.05(5) 1.11(8) 0.92(4s) 
Traveling 0.80(6) 0.70(12s) 0.62(6s) 0.73(11s) 1.50(6s) 1.15(6s) 1.60(9s) 1.40(4.5s) 
 
VI. DECK BEAM RESPONSE 
When we compare the axial forces under different conditions listed in Table 5 we can see that, the axial force is 
more for earthquake wave with travelling effect like pounding force. That is larger pounding force will result in 
larger axial force in beams. But the axial force is more in end spans compared to the middle span. 
 
Table 5 Peak axial force in deck beams (x10
7
N) 
    LOCATION Left Abutment Middle Span Right Abutment 
Uniform 1.98 0.35 2.05 
Traveling 2.36 0.75 2.40 
 
VII. THE BEARING DISTORTION 
Table 6 shows that for all cases, distortion of bearing is more at interior piers, so it is clear that the 
intermediatesupports are the main pounding positions. 
 
Table 6 The peak distortion of bearings 
Direction Longitudinal Transverse 
Location 
Left 
Abutment 
Left int. 
Pier 
Right 
int. 
pier 
Right 
abutment 
Left 
Abutment 
Left 
int. 
Pier 
Right 
int. 
pier 
Right 
abutment 
Uniform 0.19 0.25 0.27 0.13 0.02 0.03 0.04 0.03 
Travelling 0.17 0.24 0.26 0.14 0.03 0.04 0.06 0.04 
 
VIII. DRIFT OF PIER 
From the numerical study, it is observed that for travelling wave effect, the longitudinal and transverse drift of 
approach span piers is larger. Longitudinal drift of middle span piers become smaller and its transverse drift 
become larger. In Table 7 the drift of piers at different locations are listed.  
 
 
 
American Journal of Engineering Research (AJER) 2013 
 
 
Recent Advances in Structural Engineering, RASE2013 Page 32 
Table 7 Drift of Piers (m) 
Direction Longitudinal Drift Transverse Drift 
PIER NO. 1 2 3 4 1 2 3 4 
Uniform 0.42 0.41 0.40 0.45 0.14 0.12 0.12 0.15 
Travelling 0.52 0.41 0.42 0.50 0.18 0.13 0.13 0.18 
 
IX. BENDING MOMENT OF PIERS 
From Table 8 and Table 9, it is clear that for travelling effect, the longitudinal bending moment of the pier of 
approach span is larger & for interior piers, the longitudinal moment is smaller for travelling wave. But the 
transverse moment for all piers is larger for travelling wave effect. 
 
Table 8 Maximum bending moment in longitudinal direction (kNm) 
LOCATION PIER BOTTOM PIER TOP 
PIER NO. 1 2 3 4 1 2 3 4 
Uniform 19.90 112.03 110.40 20.271 36.67 164.30 165.23 35.11 
Travelling 21.30 115.11 113.20 22.12 38.00 168.25 168.14 36.32 
 
 
Table 9 Maximum bending moments in transverse direction (kNm) 
LOCATION PIER BOTTOM PIER TOP 
PIER NO. 1 2 3 4 1 2 3 4 
Uniform 13.45 82.41 83.24 14.00 10.14 50.28 51.23 12.32 
Travelling 15.14 85.66 86.58 15.32 12.65 53.22 55.25 14.22 
 
X. CONCLUSION  
The comparison between under uniform excitation or under multi-support excitation with travelling 
effect shows that, the number of pounding is less when considering travelling wave effect but the pounding 
force at pounding locations are larger. Also, the axial force under travelling wave effect is more. The approach 
span’s response is changing more compared to the main span’s response under travelling wave effect. Under 
travelling wave effect the drift and bending moment of approach span found to be more. 
 
REFERENCES  
[1] M eng, Q. and  Yin X. (2011),”3D seismic pounding effect in high pier bridges”, Advanced materials 
research,368-373, 695-703. 
[2] Jankowski, R. Wilde, K. and Fujino Y. (1998), “Pounding of superstructure segments in isolated elevated 
bridge during earthquakes”, Earthquake Engineering and Structural Dynamics,27(5),487–502. 
[3] Lindsay, B. Li, B. Chouw N. and Butterworth J. W. (2011),”Seismic pounding of bridge superstructures 
at expansion joints” , Proceedings of the Ninth Pacific Conference on Earthquake Engineering Building 
an Earthquake-Resilient Society, Auckland, New Zealand. 
[4] Tecchio, G. Grendene, M. and Modena C.  (2012), “Pounding effects in simply supported bridges 
accounting for spatial variability of ground motion: a case study”, Advances in Civil 
Engineering,2012,Article ID 267584,10 pages. 
[5] Deodatis G. (1996), “Non-stationary stochastic vector processes: seismic ground motion applications”, 
Probabilistic Engineering Mechanics, 11(3),149–167. 
[6] Lupoi, A. Franchin, P. Pinto, P. E. and Monti G. (2005), “Seismic design of bridges accounting for 
spatial variability of ground motion”, Earthquake Engineering and Structural Dynamics,34(4-5),327–
348. 
[7] Muthukumar, S. and DesRoches R. (2006), “A hertz contact element model with nonlinear damping”, 
Earthquake engineering structures, l35,811–828. 


Seismic Pounding of Bridges due to Multi-Support Excitation with traveling wave

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Seismic Pounding of Bridges due to Multi-Support Excitation with traveling wave

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