Yannick Martin, ing. jr. Chuck A. Plaxico, Ph.D. Charles-D. Annan, - PowerPoint PPT Presentation

Yannick Martin, ing. jr. Chuck A. Plaxico, Ph.D. Charles-D. Annan, Ph. D, P. Eng Mario Fafard, Ph. D., ing . 21e Colloque sur la progression de la recherche québécoise sur les ouvrages d’art May 7, 2014

 Mise en contexte  Pratiques au Canada  Pratiques aux États-Unis  Synthèse  Conclusion

 Dispositif de retenue: Limite infranchissable de la voie carrossable ◦ Atténue les conséquences d’une sortie de route de véhicule ◦ Directement lié à la sécurité des usagers [Kimball et al. 1999]

 Conception: nouveaux systèmes testés à grandeur réelle ◦ Testés selon rapport 350 du NCHRP (Ross, 1993) ◦ CSA-S6 s’appui sur AASHTO  Plusieurs dispositifs standards déjà approuvés ◦ Commentaire CSA-S6, Manuel du MTQ  Nécessité de les modifier? ◦ Améliorer la performance ◦ Réduire les coûts de fabrication ◦ Adapter le dispositif à une structure particulière

 Les modifications sont permises seulement si on peut démontrer que celles- ci n’affectent pas l’interaction entre le dispositif et le véhicule lors de l’impact . ◦ Identifier l’effet de la modification ◦ Démontrer que la performance de la barrière est conservée ◦ Outils: Rapport de l’essai de collision et notes de calcul  Approprié pour les changements mineurs avec un effet positif

 L’ancrage d’un dispositif doit résister aux charges de l’essai d’impact ◦ L’ancrage doit pouvoir développer la résistance maximale du poteau OU résister aux charges prescrites ◦ Charges tirées de la 2 e version de AASHTO LRFD (1998)

 Brief History of Accepted Evaluation Practices  Current Policy of FHWA ◦ New Hardware Designs ◦ Modifications to Existing Designs  Example - Modification to Bridge Rail Mount

 As of January 1, 2011 ◦ All new hardware must be full-scale crash tested according to MASH criteria. ◦ Existing hardware with Report 350 approval status may remain in place and may continue to be manufactured and installed.

 Existing systems are often modified for a variety of reasons, for example to: ◦ Improve crash performance, ◦ Reduce manufacturing cost, ◦ Accommodate installation/mounting to a different structure, etc.  How do such changes get approved under the new FHWA requirements? ◦ Does the system have to be retested?  If so, which crash test procedures are required? The new (more severe) crash testing criteria of MASH?  Or, the test procedures for which the system was previously approved  (e.g., Report 350)? ◦ Could alternative methods be used to evaluate the modification?

Test Vehicles Report 350 / 180 MASH AASHTO ‘98 160 2.4 kip 1.8 kip 140 54% Impact Severity (kip-ft) 62 mph 62 mph 120 25 deg. 20 deg. 100 small car test 80 5.0 kip 4.4 kip pick-up test 62 mph 60 62 mph SUT test 25 deg. 25 deg. 40 20 18 kip 22 kip 0 Report 350 (TL-4) MASH 50 mph 56 mph AASHTO '98 (PL-2) (TL-4) 15 deg. 15 deg. 2 nd Ed. Test Procedure

 On May 12, 2012, the FHWA instituted a new Federal-Aid Reimbursement Eligibility process .  All New Hardware ➔ MASH Full-Scale Testing  Modifications to already accepted hardware were categorized into three categories: 1. Significant 2. Non-Significant: Effect is Positive or Inconsequential 3. Non-Significant: Effect is Uncertain

Full Scale Petition FHWA Testing for Approval (MASH) (1) (2) Exam ample les • System height (3) • Barrier face geometry • Material Type • System components (e.g., different post size) http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/acceptprocess/

Full Scale Petition FHWA Testing for Approval (MASH) (1) (2) Exam ample les (3) • Increase gauge thickness of rail element • Modify barrier face geometry within a “known” tolerance • (All are reviewed on a case by case basis) http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/acceptprocess/

Full Scale Petition FHWA Testing for Approval (MASH) (1) (2) Exam ample les • Dissimilar method of fastener (e.g., welded vs. bolted) (3) (3) (3) • Substitute successfully crash tested component into system for identical use • Change in component design (e.g., bridge rail mount) http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/acceptprocess/

 (3 (3) ) No Non-Significan Significant: t: Ef Effect fect is is Unce Uncertain rtain Full-Scale Testing ◦ Acceptable evaluation procedures:  Performing full-scale crash testing under MASH criteria  The LS-DYNA non-linear, dynamic finite element code ◦ Report 350 testing is no longer permitted FEA ◦ So at the moment, modifications to a Report 350 system design can only be evaluated through FEA – or in some cases, dynamic component testing. ◦ Evaluation of the system must be “independently certified” by an organization that is on the FHWA’s list of accredited laboratories .

Laboratory Contact(s) Dip ipartimen timento to di i Sc Scienze ienze e Tecnologie ologie Aer erosp ospaz azial iali Marco Anghileri Phone: +39 02 2399 8316-7162 -7152 Milano- ITALY marco.anghileri@polimi.it E-Tech ch Testin ting g Se Servi vice ces, s, Inc. c. John LaTurner Rocklin, California Phone: (916) 644-9146 John.laturner@trin.net Ge George ge Mason Un Univ iver ersi sity Dhafer Marzougui Center for Collision Safety and Analysis Phone: (703) 993 4680 Fairfax Virginia dmarzoug@gmu.edu Mid idwes west t Roadside ide Sa Safet fety Facili ility Ronald K. Faller University of Nebraska-Lincoln Phone: (402) 472-6864 Lincoln, Nebraska rfaller@unl.edu George Washington University Umashankar Mahadevaiah Phone: (703) 726 8326 National Crash Analysis Center ushankar@ncac.gwu.edu Ashburn, Virginia RoadSafe LLC Chuck A. Plaxico Phone: (614) 578-1942 Canton, Maine chuck@roadsafellc.com www.roadsafellc.com Texas A&M Transportation Institute D. Lance Bullard, Jr. Phone: (979) 845-6153 Texas A&M University l-bullard@tamu.edu College Station, Texas

Modifications to the Design of an Existing Report 350 Test Level 4 Bridge Rail to Accommodate Installations on Through Truss Bridges. NETC 4-Bar Bridge Rail (PL-2 / Report 350 TL-4) Concrete Bridge Structure Steel Through-Truss Bridge

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1) Develop a finite element model of an existing hardware that is Report 350 or MASH compliant. 2) Validate the model by comparing the model results to an existing full-scale crash test on the system, using the procedures outlined in NCHRP Document 179. 3) 3) In Incor orpor orate te desi sign gn mo modifi ficati tion( on(s) ) int nto o th the FE mo model (e (e.g., cha hange nge mo moun unt t desi sign gn). ). In this case, the modifications included only those  necessary for attachment to the bridge structure. Original Mount

50.8 mm 137 mm Original Mount Design Modified Mount Design

50.8 mm 137 mm

1) Develop a finite element model of an existing hardware that is already a Report 350 or MASH compliant system. 2) Validate the model by comparing the model results to an existing full-scale crash test on the system, using the procedures outlined in NCHRP Document 179. 3) Incorporate design modification(s) into the FE model (e.g., change mount design). 4) 4) Use e FEA EA to to simula mulate te th the requi quired red fu full- scale le te tests sts and nd eva valua uate te the system’s perfo form rmance. ance.

1) Develop a finite element model of an existing hardware that is already a Report 350 or MASH compliant system. 2) Validate the model by comparing the model results to an existing full-scale crash test on the system, using the procedures outlined in NCHRP Document 179. 3) Incorporate design modification(s) into the FE model (e.g., change mount design). 4) Use FEA to simulate the required full- scale tests and evaluate the system’s performance. 5) 5) Com ompare results esults to to t the he or origi gina nal l desi sign gn to to ensu nsure re th that t th the e cha hange nge wa was pos ositi tive ve or “insignificant” regarding crash perfo form rmance. ance.