Experimental Performance and Recommendations for Qualification of Post-installed Anchors for ...

345 Pages·2013·16.61 MB·English

Experimental Performance and Recommendations
for Qualification of Post-installed Anchors for
Seismic Applications

Von der Fakultät Bau- und Umweltingenieurwissenschaften
der Universität Stuttgart zur Erlangung der Würde eines
Doktor-Ingenieurs (Dr.-Ing.) genehmigte Abhandlung

Vorgelegt von
Philipp Mahrenholtz
aus Braunschweig

Hauptberichter: Prof. Rolf Eligehausen
Mitberichter: Prof. Tara Hutchinson
Prof. Jan Hofmann

Tag der mündlichen Prüfung: 1. Juni 2012

Institut für Werkstoffe im Bauwesen der Universität Stuttgart
2012
I
Mitteilungen des Instituts für Werkstoffe im Bauwesen; Band 2013/1

Mahrenholtz, P.: Experimental performance and recommendations for qualification of post-installed anchors for
seismic applications

Herausgeber: Institut für Werkstoffe im Bauwesen der Universität Stuttgart
Prof. Dr.-Ing. Harald Garrecht
Prof. Dr.-Ing. Jan Hofmann
Anschrift: Institut für Werkstoffe im Bauwesen
Pfaffenwaldring 4
70569 Stuttgart
oder:
Universität Stuttgart
Institut für Werkstoffe im Bauwesen
70550 Stuttgart
Telefon: [phone]
Telefax: (0711) 685 63349

Redaktion: Dr.-Ing. Joachim Schwarte
Dipl.-Bibl. Monika Werner

D93

(cid:211) IWB; Stuttgart 2013

Alle Rechte vorbehalten

ISSN 0932-5921
ISBN 978-3-9811682-7-3

II
Abstract
Ensuring the technical suitability of post-installed concrete anchors by means of
pre-qualification has proved of great value over the last decades. A large variety of
pre-qualified anchor products are available and designers, authorities and
contractors can pick the most suitable and economic anchor product for the targeted
use. While this system gained in general a high degree of refinement, the seismic
application of anchors is still not well covered. For this reason, increased efforts were
recently put on the research of seismic anchor performance.
The research presented in this thesis contributed its share. This thesis constitutes a
systematic and comprehensive approach to seismic anchor qualification based on
extensive investigations. The goal of this work is to close the gap in knowledge
relating to seismic anchor behaviour to enable amendments to existing qualification
guidelines by meaningful tests allowing the assessment of the seismic performance.
The initial scope of this thesis is to provide the foundation necessary to come up with
a comprehensive scheme for the seismic qualification of post-installed anchors. After
a brief introduction of the motivation, background and objectives of the research on
anchors for use in seismic applications (Chapter 1), the state of the art of current
qualification guidelines is discussed (Chapter 2). The extensive investigations carried
out to overcome identified deficits in knowledge are presented and the key results
are discussed (Chapter 3). Points identified as critical for seismic anchor
performance supported the development of the seismic amendment of the European
qualification guideline which testing protocols were verified by tests (Chapter 4).
While the aforementioned tests were conducted under simulated seismic conditions,
the tests presented in the second part were conducted under real seismic conditions.
Therefore, shake table tests were carried out which enabled the comparison of the
anchor behaviour on component and system level. The target was to evaluate
whether the concept of future seismic pre-qualification tests sufficiently replicate the
characteristic demands of a real earthquake. The test data was compared with the
stipulated requirements and assessment criteria of the proposed pre-qualification
tests (Chapter 5). Based on all test investigations, recommendations for seismic
anchor pre-qualification are given and important aspects of seismic design are
highlighted (Chapter 6). To predict the displacement behaviour, which is often critical
for seismic qualification, a model to estimate the anchor displacement for a given
load and crack demand is proposed (Chapter 7). Finally the findings are summed up
and open questions requiring further research are formulated (Chapter 8).
III
Kurzfassung
Der Nachweis der technischen Eignung von nachträglich im Tragwerk installierten
Dübeln mit Hilfe von Zulassungsverfahren hat sich in den vergangenen Jahrzehnten
etabliert und bewährt. Aus einer großen Auswahl an zugelassenen Dübeln können
sich Planer, Behörden und Bausausführende für die jeweilige Anwendung geeignete
und wirtschaftliche Produkte auswählen. Während dieses System im Allgemeinen
sehr ausgereift ist, werden die besonderen Belastungen, die im Falle von Erdbeben
auf Dübeln wirken, bis dato noch nicht ausreichend berücksichtigt. Dies hat in den
letzten Jahren zu einer verstärkten Anstrengung in der Erforschung des Verhaltens
von Dübeln unter Erdbebeneinwirkungen geführt.
Die in dieser Promotionsarbeit vorgestellte Forschung leistet hierzu einen Beitrag.
Sie stellt eine systematische und umfassende Behandlung der seismischen
Qualifikation von Dübeln dar und basiert auf umfangreiche Untersuchungen. Das Ziel
dieser Arbeit ist es, Wissenslücken über das Verhalten von Dübeln unter
Erdbebenbelastung so zu schließen, dass bestehende Qualifikationsrichtlinien um
sinnvolle Versuche für die Beurteilung der Erdbebentauglichkeit ergänzt werden
können.
Im Rahmen der Promotionsarbeit werden zunächst die Grundlagen erarbeitet, die für
einen fundierten Ansatz zur seismischen Qualifikation notwendig sind. Nach einer
kurzen Einleitung über die Motivation, Hintergründe und Ziele der Erforschung von
Dübeln unter Erdbebenbelastungen (Kapitel 1), wird der gegenwärtige Stand der
Qualifikationsrichtlinien erörtert (Kapitel 2). Die zur Beseitigung der daraus
abgeleiteten Kenntnisdefizite durchgeführten Untersuchungen werden anschließend
präsentiert und diskutiert (Kapitel 3). Jeder Aspekt, der als maßgeblich zur
Charakterisierung des Verhaltens von Dübeln unter Erdbebeneinwirkung erkannt
wurde, unterstützte die Erarbeitung einer entsprechenden Ergänzung der
europäischen Qualifikationsrichtlinie, deren Prüfprotokolle anhand weiterer Versuche
verifiziert wurden (Kapitel 4).
Während die vorgenannten Versuche unter simulierten Erdbebenbedingungen
durchgeführt wurden, wurden die Dübel bei den im zweiten Teil der Promotionsarbeit
beschriebenen Versuchen unter realen Erdbebenbedingungen untersucht. Hierfür
wurden Rütteltischversuche durchgeführt, die einen Vergleich des Verhaltens eines
im Tragwerk eingebauten Dübels mit dem eines im Versuchskörper eingebauten
Dübels ermöglichen. So konnte geklärt werden, ob das Konzept der zukünftigen
Qualifikationsrichtlinien die charakteristischen Anforderungen eines echten
Erdbebens widerspiegeln. Die Versuchsergebnisse wurden den vorgeschlagenen
Anforderungen und Bewertungskriterien gegenübergestellt (Kapitel 5). Basierend auf
den gewonnenen Erkenntnissen werden Empfehlungen für die seismische
Qualifikation von Dübeln abgeleitet und wichtige Bemessungsaspekte aufgezeigt
IV
(Kapitel 6). Um das für die seismische Qualifikation oftmals maßgebende
Verschiebeverhalten besser vorhersagen zu können, wird ein Modell zur
Abschätzung der sich aus zyklischen Lasten und sich zyklisch öffnenden und
schließenden Rissen ergebenen Dübelverschiebung vorgeschlagen (Kapitel 7).
Abschließend werden die wesentlichen Erkenntnisse zusammengefasst und offene
Fragen formuliert, die weitere Untersuchungen erfordern (Kapitel 8).

V
Acknowledgement
First of all I would like to thank my PhD advisor Professor Rolf Eligehausen for his
strong commitment to my doctoral work which continued steadily beyond his
retirement. As my work at the Institut für Werkstoffe im Bauwesen, Universität
Stuttgart (IWB) covered a broad range of anchor technology, I benefited from
Professor Rolf Eligehausen’s remarkable expertise in this field of engineering. His
support of my ideas for investigational approaches was very encouraging and
resulted ultimately in a very challenging, but in many aspects rewarding stay at the
University of California, San Diego (UCSD), a lighthouse of eathquake engineering.
Professor Tara Hutchinson (UCSD) was not only a wonderful host on a professional
and private level; she also served as a reputable source of knowledge in seismic
engineering during my research career. Her apparently inexhaustible drive was
always an inspiration to me and I am thankful for her enthusiastic acceptance to be a
co-reviewer of my PhD thesis.
I appreciate the instant support I experienced by co-reviewer Professor Jan Hofmann
(IWB) when proposing the visiting stay at the UCSD and for giving me the opportunity
to wrap up the research I conducted along five years of laboratory work, graduate
teaching, computer administration and other obligations. I thank him to be member of
the reviewing committee. Sincere thanks are given to Professor Manfred Bischoff for
taking the chair of the examination board.
I also would like to express my thanks to Professor Hans-Wolf Reinhardt (IWB) for
his fortunate support in applying for governmental research funding. My thanks also
go to Dr. Jörg Asmus (IEA Engineering Office) and Dr. Werner Fuchs (IWB) for the
advice on friction tests, Professor Rob Dowell (San Diego State University) for the
exchange on ductility, and Dr. Dieter Lotze (MPA Governmental Material Testing
Institute) for his consultancy on group testing. Dr. Thilo Pregartner (formerly at IWB)
is thanked for the fruitful discussions on many specific topics.
Administrative staff of both universities had worked in the background to get things
organised. The support of Heidi Bauer, Gisela Baur, Silvia Choynacki and Regina
Jäger from the IWB, Simone Stumpp from the MPA, as well as Lynda Tran and
Lindsay Walton from the UCSD is gratefully acknowledged. The dedicated and
persistent support by IWB librarian Monika Werner is also highly appreciated.
Laboratory staff of both universities was a pleasure to work with in a team. Eugen
Lindenmeier and Peter Scherf are thanked for helping me with my always
extraordinary servo control systems and test setups in the Anchor Lab, and Paul
Greco is thanked for his outstanding commitment and diligent work style which was
an important factor for the successful accomplishment of the shake table tests in the
Powell Lab. Both laboratory managers, Bernd Schlottke and Andrew Gunthardt, are
thanked for making their lab an enjoyable place to work.
VI
To a great extent, the research incorporated in this dissertation was funded by the
company Hilti. For the financial support, but also for the mutual trust, I would like to
thank Dr. Ulrich Bourgund, John Silva, and particularly Dr. Matthew Hoehler.
Opinions, conclusions, and recommendations expressed in this thesis, however, are
those of the author, and do not necessarily reflect those of the sponsor. The stay at
the UCSD was also co-funded by the German Academic Exchange Service (DAAD)
which is greatly appreciated.
I also owe my thanks to my colleagues at the IWB and fellow students at the UCSD
for whatever they taught me or for backing me on the long run to the end – this holds
in particular for the sandwich generation who helped me to endure when I had to
chew more than I bit off: Walter Berger, Ronald Blochwitz, Josipa Bošnjak, Barbara
Chang, Stefan Fichtner, Yangyang Gao, Cenk Köse, Michael Potthoff, Saurabh
Prasad, Dénes Sándor, Marina Stipetic, Wentao Zhu. Particular thanks go to
Dr. Derrick Watkins (formerly at UCSD) and Dr. Richard Wood (formerly at UCSD),
as well as to Dr. Christoph Mahrenholtz (formerly at IWB) and Akanshu Sharma
(Bhaba Atomic Research Centre (BARC) and IWB) for sharing their professional
experience and friendship over the years, and for proofreading my thesis.
Finally, I would like to thank my wonderful wife and daughter for their many years’
patience when their husband and father left home in the crack of dawn and returned
late-night.

VII
VIII
Table of Contents
Table of Contents
Abstract III
Kurzfassung IV
Acknowledgement VI
Table of Contents IX
Notation XVII
1 Introduction 1
1.1 Motivation for Research on Anchors for Use in Seismic Regions 1
1.2 Context of Research on Post-installed Anchors for Seismic Applications 5
1.3 Objective of Research on Seismic Anchor Performance and Qualification 10
2 State of the Art of Qualification Guidelines 13
2.1 General 13
2.1.1 Design, Technical Approval, and Qualification of Anchors 13
2.1.2 European and German Anchor Qualification Guidelines 15
2.1.3 US Anchor Qualification Guidelines 16
2.1.4 Suitability and Serviceability Tests 17
2.1.5 Concrete strength classes 18
2.1.6 Mean and Characteristic Strength 19
2.1.7 Residual capacity, a -factors, and reduction 19
2.2 Loading Rate 20
2.2.1 European and German Anchor Qualification Guidelines 20
2.2.2 US Anchor Qualification Guidelines 21
2.2.3 Conclusions 21
2.3 Anchor Ductility 21
2.3.1 European and German Anchor Qualification Guidelines 22
2.3.2 US Anchor Qualification Guidelines 23
2.3.3 Conclusions 23
2.4 Anchor Groups 24
2.4.1 European and German Anchor Qualification Guidelines 24
2.4.2 US Anchor Qualification Guidelines 26
2.4.3 Conclusions 26
2.5 Cyclic Loads 27
2.5.1 European and German Anchor Qualification Guidelines 27
2.5.2 US Anchor Qualification Guidelines 28
2.5.3 Conclusions 29
IX
Table of Contents
2.6 Cyclic Cracks 31
2.6.1 European and German Anchor Qualification Guidelines 31
2.6.2 US Anchor Qualification Guidelines 33
2.6.3 Conclusions 33
2.7 Simultaneous Load and Crack Cycling 35
2.8 Summary 36
3 Studies at Component Level: Simulated Seismic Tests 38
3.1 General 38
3.1.1 Anchor types 38
3.1.2 Failure modes and ultimate capacity 40
3.1.3 Concrete strength 42
3.1.4 Drill bit diameter 42
3.1.5 Seismic crack width 43
3.2 Loading Rate 43
3.2.1 State of knowledge 43
3.2.2 Pullout tests with various loading rates 45
3.2.2.1 Definition of loading rates 46
3.2.2.2 Definition of failure modes 47
3.2.2.3 Test setup and testing procedure 49
3.2.2.4 Experimental results and discussion 50
3.2.3 Additional testing on anchor friction mechanisms 52
3.2.3.1 Modified FEP II tests 53
3.2.3.2 Indentation tests 58
3.2.4 Conclusions 62
3.3 Anchor Ductility 63
3.3.1 State of knowledge 63
3.3.2 Background 65
3.3.2.1 Ductility in material sciences 65
3.3.2.2 Ductility in seismic engineering 67
3.3.2.3 Ductility in anchor technology 67
3.3.3 Development of anchor ductility parameters 69
3.3.3.1 Behavioural objectives and deformation parameters 69
3.3.3.2 Characteristic points and potential ductility parameters 71
3.3.4 Evaluation of data base 75
3.3.4.1 Characteristics of load-displacement curves and anchor types 75
3.3.4.2 Tension deformation capacities and percentage elongation criteria 77
X