Simulation of vehicle crash into bridge parapet using Abaqus/Explicit

102 Pages·2015·5.33 MB·English

DEGREE PROJECT, IN DIVISION OF STRUCTURAL ENGINEERING AND
BRIDGES , SECOND LEVEL
STOCKHOLM, SWEDEN 2015
Simulation of vehicle crash into bridge
parapet using Abaqus/Explicit
DALY OGMAIA & SEBASTIAN ELIAS TASEL
KTH ROYAL INSTITUTE OF TECHNOLOGY
DEPARTMENT OF CIVIL AND ARCHITECTURAL ENGINEERING
TRITA BKN. MASTER THESIS 451
ISSN 1103-4297
ISRN KTH/BKN/EX-451-SE
www.kth.se

Preface
Firstly, we would like to thank ELU Konsult AB and our examiner Costin Pacoste for
introducing and giving us the opportunity to write this thesis. Special thanks to Frank
Axhagforhissupervisionduringtheprocessofthemasterthesis. ManythankstoAbbas
Zangeneh at KTH/ELU Konsult AB for the support and guidance during the master
thesis.
Alsowewouldliketothankourteachersandassistantsforeverythingtheyhavethought
us during our five years at KTH. Many thanks to our fellow students for making the
time at KTH a pleasant journey. Finally, we would like to thank our family and friends
for their support.
At last, we hope that you as a reader will enjoy reading this report. A lot of e↵ort and
time has been invested in order to make the report interesting and easy to follow.
June 2015
Daly Ogmaia
Sebastian Elias Tasel
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Abstract
Safety is an important aspect when designing bridges and roads. One aspect among
others to consider is the road restraint systems. The focus of this study was centered
to safety barriers which are the vehicle parapets/guardrails. The parapet must meet
certain requirements specified in European Standard in order to obtain a CE-marking,
indicating the acceptance of use. Full-scale test must be performed for a proposed
parapet to evaluate the performance. Often several full-scale tests are performed in
order to achieve CE-marking, making it an expensive process.
The primary objective of this master thesis was to investigate if Abaqus/Explicit could
be used as the finite element software for simulation of crashes. Secondary objective was
to investigate how well a performed full-scale crash could be simulated in Abaqus/Ex-
plicit. A full-scale test was conducted and the parapet installation and vehicle used was
modeled. Same conditions as in the full-scale were used in the simulation.
The results indicated that it is possible to simulate the full-scale crash using Abaqus/-
Explicit. However, the behavior of the full-scale test was not completely captured. The
maximumdynamicandpermanenthorizontaldeflectionofthetabularthriebeaminthe
full-scale test was 582 mm and 515 mm, corresponding value from the simulation was
703 mm and 643 mm.
The conclusion from the results is that Abaqus/Explicit is a suitable finite element
software for simulating crashes. The di↵erences between the full-scale test and the
simulations in this master thesis were due to the simplifications and assumptions used
when modeling the parapet, bridge deck and the vehicle. The overall global behavior
of the full-scale test was not captured, however the simulation results were not far from
the full-scale test even though rough simplifications and assumptions were used in the
modeling. We believe that with more care to details in modeling, it should be possible
to have better convergence between simulation and the full-scale test.
Keywords: Parapet, Guardrail, Vehicle crash, Full-scale test, Abaqus/Explicit, Simu-
lation
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Sammanfattning
S¨akerhet ¨ar en viktig aspekt vid utformningen av broar och v¨agar. En av aspekterna
somm˚astebeaktas¨arutformningenavv¨agr¨acken. Dessav¨agr¨ackenm˚asteuppfyllavissa
krav som anges i Europeisk standard f¨or att erh˚alla s˚a kallad CE-m¨arkning, som anger
godk¨annande av anv¨andning. Verkliga tester m˚aste utf¨oras f¨or ett f¨oreslaget v¨agr¨acke
f¨or att evaluera prestanda och d¨arigenom erh˚alla CE-m¨arkningen. Denna process kan
bli kostsam d˚a flera tester kan beh¨ova g¨oras f¨or att uppn˚a r¨att prestanda.
Syftet med detta examensarbete var att unders¨oka om Abaqus/Explicit kan anv¨andas
som finita element program f¨or att utf¨ora kraschsimulering och hur v¨al en genomf¨ord
verklig krasch kan simuleras. Ett verkligt test studerades, v¨agr¨acket, brobaneplat-
tan och fordonet som anv¨andes vid denna test modellerades i Abaqus/CAE. Samma
f¨oruts¨attningar som i testet anv¨andes i simuleringen.
Resultaten tyder p˚a att det ¨ar m¨ojligt att simulera verkliga krascher i Abaqus/Explicit.
Det globala beteendet av testet f˚angades inte upp helt i simuleringen men beteendet var
dock inte allt f¨or l˚angt ifr˚an. Den maximala dynamiska och permanenta horisontella
utb¨ojningen av profilr¨acket uppgick till 582 mm respektive 515 mm, motsvarande v¨arde
fr˚an simuleringen var 703 mm respektive 643 mm.
Slutsatsen ¨ar att Abaqus/Explicit ¨ar ett l¨ampligt finita element program f¨or simu-
lering av krascher. Skillnaderna mellan verkliga testet och simuleringen ¨ar p˚a grund
av de f¨orenklingar och antaganden som har gjorts vid modellering av brobaneplattan,
v¨agr¨acket och fordonet. Vi tror att med mer omsorg kring detaljerna i modelleringen
g¨allande brobaneplattan och v¨agr¨acket, b¨or det vara m¨ojligt att ha en b¨attre konvergens
mellan simuleringen och verkliga testet.
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Contents
Preface i
Abstract iii
Sammanfattning v
Abbreviations xiii
Symbols xiv
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Summary of previous work . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3.1 Conclusions from previous work . . . . . . . . . . . . . . . . . . . . 3
1.4 Scope and limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Finite Element Theory 5
2.1 General about Abaqus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Abaqus/Explicit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Essential di↵erences between implicit and explicit . . . . . . . . . . . . . . 7
2.4 Automatic time incrementation and stability . . . . . . . . . . . . . . . . 8
2.4.1 Definition of the stability limit . . . . . . . . . . . . . . . . . . . . 9
2.4.2 Fully automatic time incrementation versus fixed time incremen-
tation in Abaqus/Explicit . . . . . . . . . . . . . . . . . . . . . . . 10
2.4.3 Mass scaling to control time incrementation . . . . . . . . . . . . . 11
2.4.4 E↵ect of material on stability limit . . . . . . . . . . . . . . . . . . 11
2.5 Energy balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Method 13
3.1 The process of the master thesis . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Full-scale crash test on the modified T8 bridge rail . . . . . . . . . . . . . 14
3.2.1 Geometry and conditions for the guardrail installation . . . . . . . 14
3.2.2 Crash test conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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