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FHWA-HRT-05-063, May 2007
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This report documents the evaluation of a concrete material model that has been implemented into the dynamic finite element code, LS-DYNA, beginning with version 971. This material model is in keyword format as MAT_CSCM for Continuous Surface Cap Model. This model was developed to predict the dynamic performance-both elastic deformation and failure-of concrete used in safety structures when involved in a collision with a motor vehicle. An example of a roadside safety structure is a concrete safety barrier that divides opposing lanes of traffic on a roadway. Default input parameters for concrete are stored in the model and can be accessed for use. This material model only replicates the concrete aggregate. Appropriate reinforcement bars or rods must be included in the structure model separately.
This report is the second of two that completely documents this material model. This report documents the testing performed to review the model's performance and accuracy of results. The first report is Users Manual for LS-DYNA Concrete Material Model 159, which documents the theoretical basis and required input format, and includes limited hypothetical problems for the user.
This report will be of interest to research engineers who are associated with the evaluation and crashworthy performance of roadside safety structures, particularly engineers responsible for predicting the crash response of such structures when using the finite element code, LS-DYNA.
Michael Trentacoste
Director, Office of Safety R&D
This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.
The United States Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
1. Report No. FHWA-HRT-05-063 |
2. Government Accession No. | 3. Recipient's Catalog No. | |
4. Title and Subtitle Evaluation of LS-DYNA Concrete Material Model 159 |
5. Report Date May 2007 |
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6. Performing Organization Code | |||
7. Author(s) Yvonne D. Murray Akram Abu-Odeh and Roger Bligh |
8. Performing Organization Report No. | ||
9. Performing Organization Name and Address APTEK, Inc. 1257 Lake Plaza Dr. Suite 100 Colorado Springs, CO 80906 Texas Transportation InstituteTexas A &M University System 3135 TAMU College Station, TX 77843 |
10. Work Unit No. (TRAIS) | ||
11. Contract or Grant No.DTFH61-98-C-00075 |
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12. Sponsoring Agency Name and Address Volpe National Transportation Systems Center 55 Broadway, Kendall Square Cambridge, MA 02142-1093 Federal Highway Administration 6300 Georgetown PikeMcLean, VA 22101-2296 |
13. Type of Report and Period Covered Final Report September 27, 2001 through December 26, 2004 |
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14. Sponsoring Agency Code | |||
15. Supplementary Notes The Contracting Officer's Technical Representative (COTR) for this project is Martin Hargrave, Office of Safety Research and Development, HRDS-04, Turner-Fairbank Highway Research Center. |
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16. Abstract An elastoplastic damage model with rate effects was developed for concrete and implemented into ls-dyna, a commercially available finite element code. This manual documents the evaluation of the concrete material model, including the selection of the concrete model input parameters. The model is evaluated through correlations with test data: drop tower impact of ⅓-scale beams (plain and reinforced), bogie vehicle impact of full-scale reinforced beams, pendulum impact of bridge rails, and quasi-static loading of a safety-shaped barrier. Although the model was developed and evaluated for roadside safety applications, it should also be applicable to many dynamic problems. The companion manual to this report is Users Manual for ls-dyna Concrete Material Model 159, FHWA-HRT-05-062. |
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17. Key Words concrete, LS-DYNA, material model, reinforced beam, New Jersey barrier, bridge rail, pendulum, bogie vehicle | 18. Distribution Statement No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161. |
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19. Security Classif. (of this report)Unclassified | 20. Security Classif. (of this page)Unclassified | 21. No. of Pages206 | 22. PriceN/A |
Form DOT F 1700.7 (8-72) | Reproduction of completed page authorized. |
Chapter 1. Introduction
Model Theory
Model Input
Limitations of Material Property Data
Evaluation Process
Evaluation Calculations
Chapter 2. Single Element Simulations
Uniaxial and Triaxial Stress
Volume Expansion
Cyclic Loading
Pressure Versus Volumetric Strain
Rate Effects
Kinematic Hardening
Chapter 3. Single Material Cylinder Simulations
Cylinder Geometry and Loading Conditions
Cylinder Tension Response
Cylinder Compression Response
Damage Modes Observed in Tests
Fixed End Conditions
Capped End Conditions
Contact Surface Type
Chapter 4. Regulation of Softening Formulation
vSingle Elements in Tension and Compression
Cylinders in Tension and Compression
Details of Each Cylinder Mesh
Demonstration of Mesh Size Sensitivity
Description of Regulatory Technique
Evaluation of Regulatory Technique
Effect of Additional Mesh Refinement on Cylinder Response
Summary Regarding Regulation
Chapter 6. Beam Drop Tower Impact Simulations
Test Data
LS-DYNA Simulations
Plain Beams
Reinforced Beams
Summary for Drop Tower Simulations
Chapter 7. Beam Bogie Vehicle Impact Simulations
Test Data
LS-DYNA Correlations
High Velocity Impact
Intermediate Velocity Impact
Low Velocity Impact
Displacement Histories
Strain Histories
Summary for Impact Simulations
Chapter 8. Texas T4 Bridge Rail
User Introduction
Overview
Pendulum Testing
Test Results
Simulation Methodology
Pendulum Model Calibration
Finite Element Model of T4 Bridge Rail
Overview of T4 Parapet/Deck Model
Meshing
Sectional Properties
Constraints and Boundary Conditions
Material Definitions
Analyses of T4 bridge Rail
Baseline Parameters
Baseline Analysis
Parametric Analyses
Modified System Analyses
Full System Analysis: Four-Bolt Design
Full System Analysis: Three-Bolt Design
Summary for Bridge Rail Analyses
Chapter 9. Analyses of Safety-Shaped Barrier
Finite Element Model
User Evaluation Results
Developer Baseline Calculations
Developer Applied Force Calculations
Summary for Safety-Shaped Barrier Calculations
Chapter 10. Summary and Recommendations
Developer Comments
User Comments
Appendix A. User Code Verification
Introduction
Case 1. Single Element Simulations
Case 2. Cylinder Runs
Case 3. Plain Concrete Beam
Case 4. Reinforced Concrete Beam
Case 5. Bogie Impact Tests
Appendix B. Developer Support of the Texas T4 Bridge Rail Analyses
Introduction
Bridge Rail Data
Parametric Studies
Fixed Parapet Computational Results
Full Deck Computational Results
Deck to Parapet Connection
Summary of Bridge Rail Calculations
Figure 14. Concrete cylinder tested as part of the bogie vehicle impact test series
Figure 22. End cap versus concrete displacement with penetration (SFS = 1)
Figure 23. End cap versus concrete displacement with little penetration (SFS = 10)
Figure 31. Refinement of each mesh used in sensitivity analyses
Figure 43. Schematic of the size effect, as suggested by Bazant and Planas.(9)
Figure 44. Refinement of the concrete beam mesh used in the size effect analyses
Figure 49. Sketch of four-point bend tests, showing dimensions in millimeters.(10)
Figure 52. All plain concrete specimens impact the bottom of the test fixture
Figure 53. Four of the eight plain concrete specimens ultimately break into five pieces
Figure 57. This preliminary calculation demonstrates the formation of one primary crack
Figure 67. Schematic of bogie vehicle impacting reinforced concrete beam
Figure 68. The beam rests on greased supports and reacts against two load frames
Figure 72. Damage dominates one side of the beam impacted at 15.9 km/h (9.9 mi/h)
Figure 83. Details of T4 rail with four-bolt anchorage and 254-mm- (10-inch-) wide parapet
Figure 84. Details of T4 rail with three-bolt anchorage and 317.5-mm- (12.5-inch-) wide parapet
Figure 85. Parapet before test P3
Figure 86. Parapet before test P5
Figure 87. Parapet damage after test P3
Figure 88. Parapet damage after test P4
Figure 89. Parapet damage after test P5, side
Figure 90. Parapet damage after test P5, rear
Figure 91. Parapet damage after test P7
Figure 92. Original pendulum model
Figure 93. Modified pendulum model
Figure 94. Comparison of the SBP model to rigid pole calibration test
Figure 95. Force-time histories for benchmark tests and spring models
Figure 96. Force-displacement relationships for benchmark tests and SBP2 model
Figure 99. Closeup view of steel rail system with four-bolt anchorage
Figure 102. Right end view of parapet-only model for four-bolt design and three-bolt design
Figure 103. Original parapet mesh used for merging nodes with steel reinforcement
Figure 104. Revised parapet mesh with steel reinforcement
Figure 105. Linear mesh biasing along the height of parapet and width of deck
Figure 106. Bell curve mesh biasing along length of parapet and uniform meshing along length of deck
Figure 108. Anchor bolt constraint to base plate
Figure 109. Contacts definitions for the T4 bridge rail model
Figure 111. Element erosion profile (simulation case02, ERODE =1) on traffic side
Figure 112. Element erosion profile (simulation case02, ERODE =1)
Figure 113. Damage fringes for simulation case02 (ERODE =1)
Figure 114. Parapet failure with fracture energies at 20 percent of baseline values
Figure 116. Parapet failure with fracture energies at 50 percent of baseline values
Figure 117. Parapet failure with fracture energies at 27.5 percent of baseline values
Figure 119. Enhanced anchor bolt-to-base plate connection model
Figure 120. Fracture profile of modified T4 system at 0.080 seconds
Figure 121. Fracture profile of modified T4 system at 0.115 seconds
Figure 122. Fracture profile of modified T4 system at 0.250 seconds
Figure 123. Profile of damaged T4 bridge rail system with four-bolt anchorage after pendulum impact
Figure 127. Profile of T4 bridge rail system with three-bolt anchorage after pendulum impact
Figure 132. Test setup for static load tests on safety-shaped barriers
Figure 133. Failure mode at end of the safety-shaped barrier
Figure 134. Measured load versus displacement for the safety-shaped barrier
Figure 135. Cross section of the Florida safety-shaped barrier with New Jersey profile.(8)
Figure 136. Cross section of Florida barrier model concrete mesh and reinforcement layout
Figure 137. Isometric view of steel reinforcement in Florida barrier model
Figure 138. Model of quasi-static load test setup
Figure 139. Fracture profile of Florida safety-shaped barrier
Figure 148. Single element under compressive loading, developer
Figure 149. Single element under compressive loading, user
Figure 150. Single element under tensile loading, developer
Figure 151. Single element under tensile loading, user
Figure 152. Single element under pure shear loading, developer
Figure 153. Single element under pure shear loading, user
Figure 154. Concrete cylinder model with inclined cross section
Figure 155. Damage fringe t = 13.498 msec
Figure 156. Damage fringe t = 13.598 msec
Figure 157. Damage fringe at t = 40 msec
Figure 158. Cross-sectional force (developer)
Figure 159. Cross-sectional force (user)
Figure 160. Plain concrete damage fringe at 1 msec (developer)
Figure 161. Plain concrete damage fringe at 4 msec (developer)
Figure 162. Plain concrete damage fringe at 20 msec (developer)
Figure 163. Plain concrete damage fringe at 30 msec (developer)
Figure 164. Plain concrete damage fringe t =1 msec (user Linux)
Figure 165. Plain concrete damage fringe t = 4 msec (user Linux)
Figure 166. Plain concrete damage fringe t = 20 msec (user Linux)
Figure 167. Plain concrete damage fringe t = 30 msec (user Linux)
Figure 168. Plain concrete damage fringe t = 1 msec (user Windows)
Figure 169. Plain concrete damage fringe t = 4 msec (user Windows)
Figure 170. Plain concrete damage fringe t = 20 msec (user Windows)
Figure 171. Plain concrete damage fringe t = 30 msec (user Windows)
Figure 172. Reinforced concrete damage fringe t = 1 msec (developer)
Figure 173 Reinforced concrete damage fringe t = 4 msec (developer)
Figure 174. Reinforced concrete damage fringe t = 16 msec (developer)
Figure 175. Reinforced concrete damage fringe t = 20 msec (developer)
Figure 176. Reinforced concrete damage fringe t = 1 msec (user Linux)
Figure 177. Reinforced concrete damage fringe t = 4 msec (user Linux)
Figure 178. Reinforced concrete damage fringe t = 16 msec (user Linux)
Figure 179. Reinforced concrete damage fringe t = 20 msec (user Linux)
Figure 180. Displacement of node 49,072 in millimeters (developer)
Figure 181. Displacement of node 49,072 in millimeters (user Linux)
Figure 182. Bogie damage, t = 4 msec (developer)
Figure 183. Bogie damage t = 8 msec (developer)
Figure 184. Bogie damage, t = 48 msec (developer)
Figure 185. Bogie damage, t = 80 msec (developer)
Figure 186. Damage fringes t = 4 msec (user Windows)
Figure 187. Damage fringe t = 8 msec (user Windows)
Figure 188. Damage fringe t = 48 msec (user Windows)
Figure 189. Damage fringe t = 80 msec (user Windows)
Figure 190. Damage, t = 4 msec (user Linux)
Figure 191. Damage, t = 8 msec (user Linux)
Figure 192. Damage, t = 48 msec (user Linux)
Figure 193. Damage t = 80 msec (user Linux)
Figure 194. Finite element model of the pendulum, rail, and fixed end of parapet
Figure 195. Damage fringes calculated with baseline properties for a fixed end parapet
Table 1. Over-reinforced beam test matrix.
Table 2. Under-reinforced beam test matrix.
Table 3. Plain concrete beam test matrix.
Table 4. Primary crack analysis of test 15 conducted at 5 m/sec (16.4 ft/sec).
Table 5. Comparison of measured and computed deflections for the over-reinforced beams.
Table 7. Comparison of measured and computed deflections for the under-reinforced beams.
Table 8. Short input format for parapet concrete material model.
Table 9. Short input format for bridge deck concrete material model.
Table 10. Long input format for parapet concrete material model.
Table 11. Long input format for bridge deck concrete material model.
Table 12. Force comparison between tests and simulation for T4 rail system with four-bolt anchorage.
Table 14. Rail deflection and pendulum crush in the Texas T4 bridge rail tests.
Table 15. Rail deflection as a function of maximum kinetic energy available.
CEB | Comite Euro-International Du Beton |
COTR | Contracting Officer's Technical Representative |
CSCM | continuous surface cap model |
FHWA | Federal Highway Administration |
FIP | Fédération Internationale de la Précontrainte |
FOIL | Federal Outdoor Impact Laboratory |
LSTC | Livermore Software Technology Corporation |
NCAC | National Crash Analysis Center |
NCHRP | National Cooperative Highway Research Program |
SBP | spring-based pendulum |
SGI | Silicon Graphics, Inc. |
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FHWA-HRT-05-063