Luận án tiến sĩ behaviour of steel concrete composite beams made of ultra high p

Behaviour of Steel-Concrete Composite Beams Made of Ultra High Performance Concrete Der Wirtschaftswissenschaftlichen Fakultät der Universität Leipzig DISSERTATION zur Erlangung des akademischen Grades Doktor-Ingenieur (Dr. Bui Duc Vinh geboren am 07 April 1972 in Vinh Phuc - Vietnam Leipzig, 9th October 2010 Foreword This thesis was the results of a long hard working period of the author, is would not have been possible without the contribution of a great number of people: First of all, I would like to thank to my supervisor Prof. Nguyen Viet Tue for giving me the opportunity to join his research group and giving me this challenging research project. I had learn a lot of thing from many hours discussion with him.

He was not only always able to push up my spirits while I was in despair with my results but also sharing with me in sad moment which I had spent, and I am very grateful for that. The experiments of this study could not have been performed without the help and technical expertise of the laboratory personnel, as of Dipl. Holger Busch, Dipl. Immanuel Wojan and many staffs at MFPA-Leipzig for conducting the experiments.

I would like to express my thanks for their support. My gratitude also goes to Dr. Nguyen Duc Tung, Dr. Jiaxin Ma, Dr.

Michael Küchler, Dipl. Jiabin Li, Dipl. Stephan Mucha, Dipl. Gunter Schenck etc.

my colleagues in IMB (Institut für Massivbau und Baustofftechnologie, Uni-Leipzig) for many valuable suggestions and discussion hours. Grateful appreciation is also due to Mrs. Sigrid Fritzsche and Mrs. Sylvia Proksch for their warm friendship and constant help during my stay in Leipzig.

I wish to thank the German Research Foundation (DFG- Deutsche Forschungs- gemeinschaft) for finance support the research project SPP 1182, which allows me take up doctoral studies at University of Leipzig, Germany. Last but not least, I want to sincerely thank my parents and especially my wife Van Anh and son Nhan for their great support and patience during my study. I hope in the future I can return all their love. Biography Bui Duc Vinh was born in Vinh Phuc, Vietnam, on the 7th April 1972.

In October 1991 he started his studies in Civil Engineering at Ho Chi Minh University of Technology (HCMUT), where he received his Bachelor degree in 1996, specialize in Coastal Engineering. He started joint Faculty of Civil Engineering (FCE), HCMUT and worked as research assistant. Two year after, 1998, he obtained Master Degree in Mechanic of Construction from University of Liege, Belgium. He continued his studies on structural engineering and focused on high strength concrete material, modelling of concrete structures.

2006, he jointed research team of Prof. Nguyen Viet Tue, at Institute for Structural Concrete and Building Materials, University of Leipzig (IMB, Uni-Leipzig). At here, his work concentrates on investigation structural behaviour of steel-concrete composite beams made of ultra high performance concrete. March 2010 he finished his dissertation under the supervision of Prof.

Nguyen Viet Tue. Leipzig, October 2010 Bui Duc Vinh vi Biography Dedicated to my parents, my wife Van Anh and my son Bui Hoang Nhan viii Biography Abstract Ultra-High Performance Concretes (hereafter, UHPC) have high mechanical strengths (fc > 150 MPa, ft > 7 MPa) and exhibit quasi-strain hardening in tension. Their very density improve durability and extend long service life. The steel-concrete composite beams with concrete slab made of UHPC possess ad- vanced properties give significant improvement in ultimate strength of the com- posite beams.

The research reported in this thesis aimed to determine the perfor- mance and structural behaviour of composite steel-UHPC elements in bending. In addition, the continuous Perfobond based shear connectors that belong to the beams was investigated as well. The Experimental assessment of the shear connector was conducted through 11 series Push-Out test with 27 specimens. In order to predict shear capacity, char- acteristic load-slip curves as well as contribution of constituents.

The connec- tors without any reinforcement show very poor ductility, the characteristic slip reached lower 1. They could be classified as non-ductile connector. The headed stud show better characteristic load-slip response, but this connec- tor often failed by shanked at the base of connector. The shear connector with added reinforcement in front cover and dowel exhibits better performance than headed stud connection in both terms of load capacity and ductility.

The test pointed out that embedded rebars in dowel play an important role in improve- ment performance of the connector. The contribution of steel fiber less important than and It is not obviously when steel fiber vary in range of 0. The structural response of the composite members under bending with the UHPC slab in compression was investigated with four points bending test of six full scale composite beams. The concrete mix contained either 1% fibres or 0.5% (by vol- ume) of straight steel fibres with concrete strength of approximately 150 MPa.

The experimental study demonstrates that the use of UHPC slab with contin- uous shear connector is possible, and it enhances the performance of composite elements in terms of resistance and stiffness. The finite element analysis of the Push-Out specimens and composite beams which tested in this investigation was carried out using software ATENA. Full three dimension models for both Push-Out specimens and composite beams were developed in order to taken into account complexity of geometry. The concrete was modelled using a Microplane M4 with parameters were calibrated accom- panying to uni-axial compression and RILEM bending test.

Modelling result showed a reasonable agreement with the experimental data. The FE simulation is not only provide ultimate strength, global behaviour but also explained local damage area as well process of collapse occurred in structures. However, the FE analysis need more improvement in concrete material model, in order to used for parameter studies. Finally, based on result of experimental and numerical investigation a numerous recommendations are issued for practical design.

The results form this work provide to better knowledge on using new UHPC in composite structures. It also contribute to provision of design code. Contents Foreword iii Biography v Abstract ix Abbreviations xv List of Symbols xvii List of Figures xix List of Tables xxvii 1. State of the art.

Context and motivation. Objectives of study. Scope of work. Structure of the thesis.

Consideration aspects of steel-concrete composite beams 7 2. Single span composite beams under sagging moment. Basic Structural Behaviour. Structural composite beam with continuous shear connection 12 2.

Perfobond shear connector (PSC). Conventional Perfobond shear connector. Modified pefobond shear connectors. Development of concrete technology.

Composite beam made of UHPC. Finite Element modelling. modelling of composite beams. Modelling of Push-Out test.

Design of composite beam. Limit state design philosophy. Methods for analysis and design. Resistant capacity of composite beam under sagging moment 26 2.

Partial shear connection. Ductile and non-ductile shear connectors. Characterization material properties of UHPC 31 3. Development of UHPC-A Historical perspective.

Constituent materials of Ultra High Performance Concrete. Principle of UHPC. Composition of UHPC. Cost of UHPC.

Material used in this work. Relevant material properties. Properties of fresh UHPC. Time dependent properties of UHPC.

Mechanical behaviour characterization. Development of compressive strength. Stress-strain behaviour in uni-axial compression. Bi-axial behaviour of UHPC.

Flexural and direct tension behaviour of UHPC. Fracture properties of UHPC. Experimental study for perfobond shear connector in UHPC 53 4. Experimental programs and specimens.

Push-Out test specimens. Arrangement for Push-Out series. Standard Push-Out test setup. Test results and observations.

Resistance and slip results. Behaviour of headed stud shear connectors in UHPC. General behaviour of perfobond shear connector in UHPC. Influence of dowel profile and test setup.

Influence of fiber content to load slip-behaviour. Influence of transverse reinforcement arrangement. Influence of embedding reinforcement through concrete dowel 72 Contents xiii 4. Summary conclusions for Push-Out test.

Experimental investigation on the structural behaviour of steel- UHPC composite beams 75 5. Experimental program for composite beams. Aim and Objectives. Design and construction of test specimens.

Test set-up and instrumentation. Analysis of the test results and observations. Structural behaviour and Observations of beam B1 and B2 83 5. Structural behaviour and Observation of beam B3 and B4.

Test results and observing of beam B5. Test results and observing of beam B6. Shear flow distribution in composite beam. Load-slip behaviour in composite beam versus Push-Out test101 5.

Distribution of longitudinal shear forces. Material models for Finite Element Modelling 107 6. Material models for structural steel and reinforcement. Microplane M4 material model for concrete.

Aspects of concrete material model. Microplane M4 material model in ATENA. Parameter study of Microplane. Setting up virtual test.

Input parameter and sensitivity analysis. UHPC experimental data. Results of M4 model parameters investigation and discussion118 6. Proposed set of parameter for UHPC.

Adjustment strategy for model parameters. Result of compression and bending modelling with M4. Finite Element Modelling 127 7. Modelling of Push Out Test.

Finite element model. Experimental validation finite element model. Local behaviour Push-Out specimens. Proposed model for prediction ultimate capacity of perfor- bond shear connector.

Modelling of composite beam. Finite element model. Validation of the FE model. Local stress distribution in steel girder and shear connectors155 7.

Shear flow on concrete dowel. Conclusions and Future Perspective 159 8. Ultra high performance concrete. Composite beam members made of UHPC under static load 160 8.

Perfobond based shear connectors in UHPC. Modelling of composite beams. Recommendations for further research. Appendices: Concrete mix proportional 165 A.

List of tables for constituent materials. Appendices: Standard Push-Out Test 169 B. Experimental results of Standard Push-Out test. List of drawings and charts.

Appendices: Bending test of composite beam 181 C. Design of steel-concrete composite beams for bending test. List of drawings and charts .