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Performance Based Design for Bridge Piers Impacted by Heavy Trucks
Anil K. Agrawal, Ph.D., P.E., Ran Cao and Xiaochen XuThe City College of New York, New York, NY
Sherif El-Tawil, Ph.D.University of Michigan, Ann Arbor, MI
1
Research in this presentation has been sponsored through a FHWAcontract on Hazard Mitigation Team with Mr. Waider Wong as theTask Manager.
ObjectivesDevelop bridge design guidelines to achieve desired
performance levels during heavy vehicular impact.
A methodology to predict impact loads based onweight and velocity
Definition of performance levels
Approach to achieve desired performance level
Step by step examples illustrating performance baseddesign and
Demonstration of effectiveness of the design throughnumerical simulations validated through physical largescale tests. 2
Outline of the Presentation
Introduction
Material Model
Large Scale Testing and Simulation
Heavy Vehicle Simulation
Performance-based Design For Heavy Vehicle
Simulation3
Highway Bridges o designed to resist
• Gravity Load• Live Load
o expected to experience extreme events• Hydraulic• Overload• Collision• Earthquake
Bridge Failures
Introduction
Introduction
Hydraulic57%
Collision13%
Overload12%
Fire3%
Earthquake1%
All Other14%
Causes of failure of bridges.
5
Major ProblemMinor Problem
Introduction
Introduction
Introduction
Introduction
Introduction
Introduction
Truck Impact on Piers of Tancahua Street Bridge over IH-37, Corpus Christi, Texas on May 14, 2014.
11
Introduction
Truck impact on Bridge on 26 ½ Road over IH-70, Grand Junction, Colorado
12
Introduction
Truck impact on Mile Post 519 Bridge over IH-20, Canton, TX
13
Introduction
Truck impact on FM 2110 bridge over IH-30, Texarkana, Texas on Aug. 8th, 1994.
14
Introduction
Truck impact on SH-14 Bridge Over IH-45, Corsicana, Texas
15
Experimental Test
Inertial restraints by the superstructures can produce the column design forces
that are more than 200% larger than those calculated by the static procedure
prescribed in AASHTO.
Introduction
Truck Impact on Bollards
Test of anti-ram bollards based on truck collision conducted by Hunan University, 2009.
Introduction
Truck Impact on Bollards
High capacity of the steel tube filled with concrete, the column didn’t go large
deformation.
Test of anti-ram bollards based on truck collision conducted by Hunan University, 2009.
Introduction
IntroductionFull-Scale Testing at TTI
19
• Tests based on impact by truck on rigid piers.• Results don’t apply to concrete piers that are damaged, resulting in
significant loss of energy.• Test results don’t provide a basis for performance based approach.
FHWA / TTI Test
The peak impact force reached 900 kips from the contact between the engine and
the pier; there is no damage in the rigid pier; 600 kips is recommended to update
AASHTO guideline.
Test of tractor-trailer and rigid steel pier collision by TTI, 2010.
Introduction
FHWA / TTI Test
The peak impact force reached 900 kips from the contact between the
engine and the pier; there is no damage in the rigid pier; 600 kips is
recommended to update AASHTO guideline.
Introduction
Medium Weight Truck
Truck FEM Model:
Weight: 15,000 pound (66 KN)
Dimension: 27 FT×8 FT×10 FT
Material Model Truck Component
Elastic Material Models Engine, Transmission, Radiator
Rubber Material Model Mounts between the cabin and rails, engine and rails,
etc.
Rate-dependent Isotropic Elastic-plastic Material Model Chassis components and the body shells
Miele, C.R., Plaxico, C. A., and Kennedy, J.C.(2005). Heavy Vehicle-infrastructure asset interaction andCollision. Heavy Vehicle Research Center, Oak Ridge National Laboratory.
TRUCK MODELS FOR THEORETICAL RESEASRCH
Truck FEM Model:
Weight: 80,000 pound (360 KN)
Dimension: 66 FT×9 FT×13 FT
Chuck A. Plaxico (2015). FEA vs TTI Test 429730-2, Preliminary Validation Analysis. Roadsafe LLC.
TRUCK MODELS FOR THEORETICAL RESEASRCH
• Heavy Weight Trucks• 80,000 lb weight
IntroductionDamage modes during vehicular impacts
24Texas I45 Bridge Accident in 2014.
Primarily shear failure mode dominant during accidents.
Material ModelsConcrete and Steel Material Models in LS-DYNA
25
Mat ID Mat Name Characteristics and ImplementationMat 17 Isotropic Elastic-Plastic With
Oriented CracksDoes not consider the pressure hardening effect, strainrate effects, and damage softening effect. Potentialapplications include brittle materials such as ceramics aswell as porous materials such as concrete in cases wherepressure hardening effects are not significant.
Mat 72 MAT_CONCRETE_DAMAGE Widely used for simulating blast and impact in concretestructures.
Mat 96 Brittle Damage Model Mainly used to simulate cracks due to tensile stress.
Mat 111
Johnson-Holmquist Concrete Model
Used for concrete subjected to large strains, high strainrates, and high pressure.
Mat 159
Continuous Surface Cap Model
Developed to simulate the deformation and failure ofconcrete in roadside safety structures impacted byvehicles
Mat 3 Plastic Kinematic This model is widely used to simulate isotropic andkinematic hardening plasticity considering rate effect.
Material ModelMat 3: Kinematic Plasticity Model for Steel Rebars
26
Elastic-plastic behavior with kinematic and isotropic hardening.
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Impact Test by Fujikake et al. (2009)
27Geometry and rebar detailing of the RC beam specimen.
28
RC beam hammer impact test setup.
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Impact Test by Fujikake et al. (2009)
29
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Default CSCM Parameters
30
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Parameters Gf 0.4_1_0.4
31
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Parameters Gf 0.4_1_0.4
32
Details of shear test setup. (Priestley et al. 1994)
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Shear Failure Simulation
33
Column Damage Levels.
Material ModelCALIBRATION OF CONTINUOUS SURFACE CAP MODEL
Shear Failure Simulation
Large Scale Testing and Simulation
34
Conceptual model of the pier-bent structure for testing and pendulum test frame system.
35
Generation of impact force time history of the impactor.
Large Scale Testing and SimulationDesign of the Impactor
36
Setup of field test.
Large Scale Testing and SimulationTest Setup
Impact Test
38
Permanent crack pattern on four sides of weak pier
Cracks on Impacted Weak Pier
Large Scale Testing and SimulationTest Results
39
Crack evolution for the weak pier impact.
Crack Development on Impacted Pier
Large Scale Testing and SimulationTest Results
40Permanent crack pattern of four sides of strong pier.
Large Scale Testing and SimulationTest Results
Cracks on Impacted Weak Pier
41
Finite element model with mesh size 1.5 inch (38 mm).
Large Scale Testing and SimulationFinite Element Validation
42
Computational model of pendulum impactor.
Large Scale Testing and SimulationTest Results
43
Pendulum nose crash process.
Impactor Crash Process
Large Scale Testing and SimulationEXPERIMENTAL VS. COMPUTATIONAL RESULTS
44
Test result of impact force and velocity of point A.
Large Scale Testing and SimulationEXPERIMENTAL VS. COMPUTATIONAL RESULTS
45
Critical points displacement for the impacting into the weak and strong column scenario.
Displacement Time History
Large Scale Testing and SimulationEXPERIMENTAL VS. COMPUTATIONAL RESULTS
Heavy Vehicle Simulation
46
FE model of tractor-semitrailer in LS-DYNA.
Truck Model
47
Engine impacts with the rigid steel pier during test and simulations.
Trailer impacts with pier during test and LS-DYNA simulation.
Heavy Vehicle SimulationTruck Model
48
Impact force time histories during the test and FEM simulation in LS-DYNA.
Heavy Vehicle Simulation
49
Whole Bridge Pier bent Model
Heavy Vehicle SimulationModeling of Pier
Displacement time history at impact point
50
Heavy Vehicle SimulationModeling of Pier
Fixed-FixedModel of piersufficient
51
Heavy Vehicle SimulationNumerical Simulation Setting
52
Heavy Vehicle SimulationExample Piers
53
Pulse model for impact force time history for impact by single unit truck on bridge piers.
Single Unit Trucks
Heavy Vehicle SimulationModelling of Vehicular Impact Force
54
Time history for impact force by the tractor-semitrailer on a rectangular concrete pier.
Heavy Vehicle SimulationVehicular Impact Force for Tractor-Semitrailers
55
Proposed triangular pulse model for heavy vehicle impacts on bridge pier.
Heavy Vehicle SimulationModelling of Vehicular Impact Force
56Contours of impact force distribution along the height of the pier for case
P36_V50_M40 (unit: kips).
Points of Application of Pulse Impact
Heavy Vehicle SimulationModelling of Vehicular Impact Force
57
Application of impact pulse loading function of the pier.
Points of Application of Pulse components
Heavy Vehicle SimulationModelling of Vehicular Impact Force
58
Heavy Vehicle SimulationModelling of Vehicular Impact Force
Damage Modes and Displacement time-histories for P3_V50_M40 case.
Heavy Vehicle SimulationParametric Study: Effect of Impact Velocity
59
0
200
400
600
800
1000
1200
20 40 60 80
Impa
ct fo
rce
(Kip
s)
Velocity (mph)
F1
0
100
200
300
400
500
600
20 40 60 80
Impa
ct fo
rce
(Kip
s)Velocity (mph)
F2
0
400
800
1200
1600
2000
20 40 60 80
Impa
ct fo
rce
(Kip
s)
Velocity (mph)
F3
050
100150200250300350
20 40 60 80
Impa
ct fo
rce
(Kip
s)
Velocity (mph)
F4
0
200
400
600
800
1000
20 40 60 80
Impa
ct fo
rce
(Kip
s)
Velocity (mph)
F5
60
0
0.005
0.01
0.015
20 40 60 80
Tim
e (s)
Velocity (mph)
T1
0.000
0.010
0.020
0.030
0.040
20 40 60 80
Tim
e (s)
Velocity (mph)
T2
0.000
0.010
0.020
0.030
0.040
0.050
20 40 60 80
Tim
e (s)
Velocity (mph)
T3
0.000
0.020
0.040
0.060
0.080
0.100
20 40 60 80
Tim
e (s)
Velocity (mph)
T4
Heavy Vehicle SimulationParametric Study: Effect of Impact Velocity
61
0
200
400
600
800
1000
1200
28 33 38 43
Impa
ct fo
rce
(Kip
s)
Pier size (in)
F1
30 mph
50 mph
70 mph
0100200300400500600700
28 33 38 43
Impa
ct fo
rce
(Kip
s)Pier size (in)
F2
30 mph
50 mph
70 mph
0200400600800
10001200140016001800
28 33 38 43
Impa
ct fo
rce
(Kip
s)
Pier size (in)
F3
30 mph
50 mph
70 mph
050
100150200250300350400
28 33 38 43
Impa
ct fo
rce
(Kip
s)
Pier size (in)
F4
30 mph
50 mph
70 mph
0
200
400
600
800
1000
1200
28 33 38 43
Impa
ct fo
rce
(Kip
s)
Pier size (in)
F5
50 mph
70 mph
Heavy Vehicle SimulationParametric Study: Effect of Pier Size
62
0.000
0.005
0.010
0.015
0.020
28 33 38 43
Tim
e (s)
Pier size (in)
T1
30 mph
50 mph
70 mph0.0000.0050.0100.0150.0200.0250.030
28 33 38 43
Tim
e (s)
Pier size (in)
T2
50 mph
70 mph
0.0000.0100.0200.0300.0400.0500.060
28 33 38 43
Tim
e (s)
Pier size (in)
T3
30 mph
50 mph
70 mph0.0000.0200.0400.0600.0800.1000.120
28 33 38 43Ti
me (
s)Pier size (in)
T4
30 mph
50 mph
70 mph
Heavy Vehicle SimulationParametric Study: Effect of Pier Size
63
0200400600800
10001200
10 30 50
Impa
ct fo
rce
(Kip
s)
Truck weight (US ton)
F1
30 mph
50 mph
70 mph
0200400600800
10 30 50
Impa
ct fo
rce
(Kip
s)
Truck weight (US ton)
F2
30 mph
50 mph
70 mph 0
500
1000
1500
2000
10 30 50Impa
ct fo
rce
(Kip
s)
Truck weight (US ton)
F3
30 mph
50 mph
70 mph
-100
100
300
500
10 20 30 40 50Impa
ct fo
rce
(Kip
s)
Truck weight (US ton)
F4
30 mph
50 mph
70 mph 0200400600800
1000
10 30 50Impa
ct fo
rce
(Kip
s)Truck weight (US ton)
F5
50 mph
60 mph
70 mph
Heavy Vehicle SimulationParametric Study: Effect of Truck Weight
64
0.000
0.005
0.010
0.015
0.020
10 20 30 40 50
Tim
e (s
)
Truck weight (US ton)
T1
30 mph
50 mph
70 mph0.000
0.010
0.020
0.030
0.040
0.050
10 20 30 40 50
Tim
e (s
)
Truck weight (US ton)
T2
30 mph
50 mph
70 mph
0.000
0.010
0.020
0.030
0.040
0.050
0.060
10 20 30 40 50
Tim
e (s
)
Truck weight (US ton)
T3
30 mph
50 mph
70 mph
0.000
0.020
0.040
0.060
0.080
0.100
10 20 30 40 50
Tim
e (s
)
Truck weight (US ton)
T4
30 mph
50 mph
70 mph
Heavy Vehicle SimulationParametric Study: Effect of Truck Weight
65
Heavy Vehicle SimulationPulse Parameters Based on Nonlinear Regression
66
Heavy Vehicle SimulationTruck Impact Versus Pulse Loading
67
Distribution of impact force pulse around the diameter of a circular pier
Heavy Vehicle SimulationCircular Piers
68
Heavy Vehicle SimulationCircular Piers
Performance-Based Design ApproachHeavy Vehicle Impacts
69
Concept developed primarily in earthquake engineering.
Performance-based design philosophy entails estimation ofseismic demands in the system and its components andchecking to see if they exceed the capacity associated with arequired performance objective for a given hazard intensitylevel.
Commonly accepted performance levels:
Immediate Occupancy (IO)
Collapse Prevention (CP)
Only preliminary development in PBD for vehicular impacts.
70
Capacity Design of Bridge Piers
Capacity design is the process whereby plastic hinge mechanisms arepromoted by providing over strength in shear at critical locations. Plastichinging is a more ductile mechanism than shear failure and can lead toincreased collapse resistance.
Performance-Based Design ApproachHeavy Vehicle Impacts
71
Shear Failure Versus Ductile Failure
Performance-Based Design ApproachHeavy Vehicle Impacts
Shear failure of bridgepiers: Not Preferred
Flexure failure of bridgepiers: PreferredCapacity design reducesthe occurrence of shearfailure
72
Performance-Based Design ApproachHeavy Vehicle Impacts
Reduction in shear deformation
(a) (b) (c)Circular section
Non-capacity designed
Capacity designed
*NC – non capacity design, *C – capacity designed PR: Plastic rotationSD: Shear distortion
• Effect of capacity design
73
(a) Minor damage. (b) Moderate damage. (c) Severe damage.
Examples of the various modes of failure by the heavy truck impact
Performance-Based Design ApproachDesign Framework
Direction of impact
Minor cover damage
Some plastichinging
Some sheardistortion, but core intact
Zone with shear cracking and largeshear distortion
Well developed plastichinge region
Shear cracks and deteriorations in core
74
Impacts by Tractor-Semitrailer
Performance-Based Design ApproachDesign Framework
Minor damage
Moderate damage
Severe damage
Minor damage
Moderate damage
Severe damage
Max(D1, D2)/C
• D1: base shear from bumper impact.• D2: base shear from engine impact.• C: shear capacity of the full section.
• D3: base shear from trailer impact.• Cs: shear capacity of the stirrups.
75
Performance-Based Design Procedure
STEP 1Strength/service
design.
STEP 3Select D/C.
STEP 4Try a pier size.
STEP 5Find D1, D2, D3
using pulse model.
STEP 6Stirrups check.
C = Max(D1, D2)/(D/C)
STEP 7Check plastic hinge.
2*Mdesign / 5 (ft) < Cdesign
STEP 2Select V and W.
STEP 8Check performance.Max(D1, D2)/Cdesign
D3/Cdesign or D3/Csdesign
76
Selected cases for validation of proposed method.
Case Truck characteristics
Columnsize
Columnheight D2/Cdesign
D3/Cdesign(D3/Csdesign)
Predicted damage
level
Max(SD, PR)
Actual damage
level
1 50mph_80kips 39in-circular 20 ft 1.40 0.64 Minor 0.003 Minor
2 60mph_80kips 33in-square 20 ft 2.22 1.31 Severe 0.161 Severe
3 60mph_40kips 33in-square 18 ft 2.25 0.78 Moderate 0.030 Moderate
4 60mph_60kips 33in-square 20 ft 2.22 1.10 Moderate 0.059 Moderate
5 40mph_80kips 33in-square 20 ft 1.85 0.55 Minor 0.003 Minor
Performance-Based Design Procedure
• D2: base shear from engine impact.• D3: base shear from trailer impact.• C: shear capacity of the full section.• Cs: shear capacity of the stirrups.
• SD: Shear distortion• PR: Plastic rotation
600 Kips AASHTO Versus Actual Impact
• Design 36” pier for 600 kips• Tractor-semitrailer (80,000 lb)
77
70 mph 50 mph 30 mph
Direction of impact
78
AASHTO PBD (moderate)
Concrete 36”x36”x192” 36”x36”x192”
Longitudinal rebar
12 #11 12 #11
Stirrups #6 @12” #6 @6”
AASHTO design Performance-based design (moderate)
600 Kips AASHTO Versus Performance-based design
• Tractor-semitrailer: 70 mph, 80,000 lb
Table. Design comparison
SUMMARY & CONCLUSIONS A performance based framework for design of piers against vehicular impacts has
been developed using calibrated models of piers and tractor-semitrailer truckbased on available test data.
A three-triangular pulse model was proposed for simulating impact by a tractor-trailer on bridge piers for design purposes.
A performance based approach for the design of bridge piers was developed byquantifying damage in terms of plastic rotation and shear distortion and theperformance in terms of demand / capacity (D/C) ratios.
The approach is simple enough for design office use and proposes three levels ofperformance immediate use, damage control and near collapse. Applicability ofthe proposed design approach was demonstrated through several cases that werenot included in the calibration of the proposed design method.
Limitations: Characteristics of the cargo: sand ballast. Pulse model parameters based on a single type of truck that had given
bumper characteristics and engine weight. Limited test data for calibration. No full scale performance verification.
79
80
Thank you Very Much.