Bond behaviour of a multi-filament yarn embedded in a cementitious matrix [Elektronische Ressource] / vorgelegt von Björn Banholzer

Banholzer

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2004
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

BOND BEHAVIOUR OF A MULTI-FILAMENT YARN EMBEDDED
IN A CEMENTITIOUS MATRIX
Von der Fakultät für Bauingenieurwesen der
Rheinisch-Westfälischen Technischen Hochschule Aachen
zur Erlangung des akademischen Grades eines
Doktors der Ingenieurwissenschaften
genehmigte Dissertation
vorgelegt von
Diplom-Ingenieur
Björn Banholzer
aus
Essen
Berichter: Universitätsprofessor Dr.-Ing. Wolfgang Brameshuber
Universitätsprofessor Dr.-Ing. Manfred Curbach
Universitätsprofessor Dr.-Ing. Hans-Wolf Reinhardt
Tag der mündlichen Prüfung: 19. August 2004
„Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.“o
ABSTRACT
Although the bond of a strand in a cementitious matrix is certainly predominated by the bond
properties between filaments and matrix, more detailed information is needed to evaluate the
failure mechanisms of such a complex system under a pull-out load and hence to allow an
analytical and numerical simulation of this composite. Thus, in this study different innovative
test methods are developed and used to identify the failure process of a strand as a result of
the pull-out process and ascertain the contact faces between the individual filaments and the
matrix. Additionally, based on these findings, numerical procedures are proposed to allow, for
the first time, to establish a direct relationship between the load history of a pull-out test, to
the failure process of an AR-glass strand, by means of a mathematical function; the so-called
active filament versus displacement relation N ( Ω). Together with the load versusF
displacement relationship P( Ω) also derived during the pull-out test, an analytical
characterization and simulation of the bond between an AR-glass strand and a cement based
matrix will be possible.
ZUSAMMENFASSUNG
Obwohl das Verbundverhalten eines Multi-Filament-Garn/Feinbeton-Systems sicherlich
maßgeblich durch den Verbund zwischen Filament und Matrix beeinflusst wird, müssen
wesentlich detailliertere Erkenntnisse vorliegen, um den Versagensprozess dieses komplexen
Systems infolge einer Pull-Out-Belastung zu beschreiben und somit eine analytische und
numerische Modellierung des Verbundwerkstoffes zu erlauben. Aus diesem Grund wurden
innerhalb dieser Arbeit innovative Untersuchungsmethoden entwickelt und angewendet, die
es nun ermöglichen, diesen Versagensprozess eines Multi-Filament-Garn/Feinbeton-Systems
infolge einer einwirkenden Pull-Out-Belastung zu identifizieren und die Grenzflächen
zwischen den individuellen Filamenten und der umgebenden Matrix zu bestimmen. Zusätzlich
wurden numerische Auswerteroutinen entwickelt, die es zum ersten Mal ermöglichen, den
Versagensprozess eines Multi-Filament-Garn/Feinbeton-Systems mit Hilfe der so genannten
„Aktiven Filamente/Ausziehweg-Funktion“ N ( Ω) mathematisch abzubilden und somit eineF
Verbindung zwischen der Belastungsgeschichte des Verbundwerkstoffes und dem Versagen
der individuellen Filamente aufzustellen. Zusammen mit der ebenfalls im Pull-Out-Versuch
ermittelten Kraft/Ausziehweg-Beziehung P( Ω) wird damit erstmals eine analytische
Beschreibung und Simulation des Verbundes zwischen Multi-Filament-Garn und
zementgebundener Matrix ermöglicht.i
ACKNOWLEDGEMENT
The research presented in this thesis was carried out during my appointment as a research
assistant and PhD student at the Institute of Building Materials Research (ibac) of RWTH
Aachen University.
I am in particular grateful to Professor W. Brameshuber for his support and advice that I have
received on so many occasions.
I thank, also, the members of my committee, Professor H.-W. Reinhardt (University of
Stuttgart) and Professor M. Curbach (Dresden University of Technology) for their interest and
valuable suggestions.
Finally I would like to thank my colleagues and friends for the generous support received
during all the years at this institute.
Most importantly, I wish to thank my parents who were a constant source of love and support.
This work was carried out within the Collaborative Research Center 532 “Textile reinforced
concrete – Basics for the development of a new technology” and sponsored by the “Deutsche
Forschungsgemeinschaft (DFG)”. The support is gratefully acknowledged.
Aachen,
Summer 2004iiiii
TABLE OF CONTENTS
1 Introduction ....................................................................................................................... 1
1.1 Objective.... 2
1.2 Proceeding..................................................................................................................... 2
1.3 Overview....................................................................................................................... 3
2 Analytical modeling of a single fiber pull-out process ................................................... 5
2.1 Introduction................................................................................................................... 5
2.2 Analytical bond models ................................................................................................ 7
2.2.1 The perfect interface model (stress approach)..................................................... 7
2.2.2 The fracture mechanical model (energy approach) ............................................. 9
2.2.3 The cohesive interface model (stress approach)................................................ 12
2.2.4 Comparison of the models................................................................................. 16
2.2.5 Which model to use? ......................................................................................... 21
2.3 The direct boundary value problem - τ(s) → P(ω) .................................................... 22
2.4 The inverse boundary value problem - P(ω) → τ(s) ................................................. 26
2.5 Summary ..................................................................................................................... 29
3 Application and validation of the cohesive interface model ........................................ 31
3.1 Introduction.................................................................................................................31
3.2 Materials composition and specimen preparation....................................................... 32
3.2.1 Experimental sequences .................................................................................... 33
3.3 Experimental methods................................................................................................. 33
3.4 Test results.. 35
3.5 Application and validation of the model..................................................................... 41
3.6 Stochastic size effects 44
3.7 Summary ..................................................................................................................... 46
4 Bond between glass filaments and a cement based matrix .......................................... 47
4.1 Introduction.................................................................................................................47
4.2 Materials composition and specimen preparation....................................................... 49
4.2.1 AR-glass filaments ............................................................................................ 49
4.2.2 Fine-grained concrete ........................................................................................ 49
4.2.3 Specimen preparation – tensile test ................................................................... 50iv Table of Contents
4.2.4 Specimen preparation – pull-out test................................................................. 51
4.2.5 Experiment sequences ....................................................................................... 51
4.3 Experimental methods................................................................................................. 52
4.3.1 Tensile test......................................................................................................... 52
4.3.2 Pull-out test........................................................................................................ 53
4.3.3 Optical microscopy............................................................................................ 54
4.4 Test results .................................................................................................................. 55
4.4.1 Tensile tests on filaments .................................................................................. 55
4.4.2 Pull-out tests on filaments ................................................................................. 57
4.5 Bond stress versus slip relations τ(s) .......................................................................... 62
4.6 Discussion ...................................................................................................................66
4.7 Summary ..................................................................................................................... 68
5 Bond between glass strands and a cement based matrix ............................................. 69
5.1 Introduction.................................................................................................................69
5.2 Materials composition and specimen preparation..................................