Verification of the response of a concrete arch dam subjected to seasonal temperature variations

103 Pages·2015·6.2 MB·English

master of science thesis
stockholm, sweden 2015
Verification of the response
of a concrete arch dam
subjected to seasonal
temperature variations
OSKAR ANDERSSON
MAX SEPPÄLÄ
TRITA-BKN. MASTER THESIS 458, 2015
ISSN 1103-4297,
ISRN KTH/BKN/EX–458–SE
KTH royal insTiTuTe of TecHnology
www.kth.se School of architecture and the built environment
Verification of the response of a concrete
arch dam subjected to seasonal temperature
variations
Oskar Andersson & Max Seppälä
June 2015
TRITA-BKN. Master Thesis 458, 2015
ISSN 1103-4297,
ISRN KTH/BKN/EX–458–SE
©Oskar Andersson Max Seppälä 2015
Royal Institute of Technology (KTH)
Department of Civil and Architectural Engineering
Division of Concrete Structures
Stockholm, Sweden, 2015
Abstract
Many dams existing today were constructed around fifty years ago. Condition mon-
itoring is essential for maintaining high safety and determining the current level
of safety and stability for these dams. There is a need for new monitoring tech-
niques and finite element coupled monitoring could be one of these techniques. A
concrete arch dam located in Sweden is modelled and calibrated with respect to
concrete temperature measurements. The temperature distribution is then defined
as a prescribed strain in a structural mechanical model in which a parametric study
is performed. The results from the parametric study are compared to measurements
of the crest deformation and a combination of parameters is found giving the lowest
difference between measurements and model results for the mid-section.
The results show that the finite element model can be used to predict the behavior
ofthedamwithacceptabledeviation. Theparametricstudyindicatesthattherefer-
encetemperatureoftheconcretehaslittleeffectontheamplitudeofthedeformation
and that the governing factor is the coefficient of thermal expansion.
Keywords: Concrete arch dams, thermal effects, ice load, condition monitoring,
finite element analysis
iii

Sammanfattning
Många av de dammar som finns idag byggdes för omkring femtio år sedan. Till-
ståndsövervakning är avgörande för att kunna bestämma nivån av säkerhet och
stabilitet för dessa dammar. Det finns ett behov av ny övervakningsteknik och
finita element-kopplad övervakning kan vara en av dessa tekniker. En betongvalv-
damm modelleras och kalibreras med avseende på uppmätt betongtemperatur. Den
beräknade temperaturfördelningen definieras sedan som en föreskriven töjning en
strukturmekanisk modell i vilken en parametrisk studie utförs. Resultaten från pa-
rameterstudien jämförs med mätningar av kröndeformation och en kombination av
parametrar identifieras som ger lägsta skillnad mellan mätningar och modellresultat
för mittsektionen.
Resultaten visar att modellen kan användas för att förutsäga dammens beteende
med acceptabel avvikelse. Parameterstudien indikerar att referenstemperaturen för
betongen har liten inverkan på amplituden för deformationen och att den styrande
faktorn är längdutvidgningskoefficienten.
Nyckelord: Betongvalvdammar, termiska effekter, tillståndsövervakning, islast,
finita element analys
v

Preface
This is a Master of Science thesis performed at the Division of Concrete Structures,
Department of Civil and Architectural Engineering at KTH Royal Institute of Tech-
nologyincollaborationwithWSPandFortumduringtheperiodJanuary-June2015.
The thesis subject was initiated by Rikard Hellgren, WSP, and supervised by Dr.
Richard Malm, KTH.
We would like to thank Dr. Richard Malm and Rikard Hellgren for the invaluable
guidance and support they have given us during this period. We would also like
to thank Sezar Moustafa at Fortum for providing us with material for the case
study and for believing in the subject and sharing useful knowledge with us. We
would further like to thank Dr. Fredrik Johansson at the Division of Soil and Rock
Mechanics for taking the time to discuss the subject and give us useful comments.
We would finally like to thank Scanscot for providing us with necessary software
licenses.
Stockholm, June 2015
Oskar Andersson & Max Seppälä
vii

Contents
Abstract iii
Sammanfattning v
Preface vii
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Aim and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Structure of the thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Concrete arch dams 3
2.1 Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1 Static loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.2 Seasonally varying loads . . . . . . . . . . . . . . . . . . . . . 5
2.1.3 Dynamic and other loads . . . . . . . . . . . . . . . . . . . . . 6
2.2 Thermal effects on concrete arch dams . . . . . . . . . . . . . . . . . 7
2.2.1 Temperature distribution . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Deflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.3 Thermal properties of concrete . . . . . . . . . . . . . . . . . 8
2.3 Finite element modelling in Abaqus/Standard . . . . . . . . . . . . . 10
2.3.1 Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.2 Heat transfer analyses of concrete arch dams . . . . . . . . . . 12
2.3.3 Convective heat transfer coefficients . . . . . . . . . . . . . . . 13
2.3.4 FE-coupled monitoring . . . . . . . . . . . . . . . . . . . . . . 16
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