Contenido Design of Hybrid Structures Where Steel Profiles Meet Concrete

Design of Hybrid Structures Where Steel Profiles Meet Concrete

Edited By André Plumier, Hervé Degée

Well-designed hybrid structures can combine the different performance strengths materials. This guide focuses on design approaches for concrete structures reinforced in an unconventional way by steel profiles. It explains force transfer mechanisms of steel profiles and oncrete interfaces, and an analysis of the characteristics of hybrid structures, including slendercomponents. Several types of hybrid designs are addressed: walls and columns with several embedded steel profiles, connections strengthened by steel profiles between steel and composite or reinforced concrete components, including the specific case of shear keys connecting deep beams or flat slabs to columns. The transition zones in partly reinforced concrete and partly composite columns are also covered.

Design of Hybrid Structures draws on the European SMARTCOCO research project of experimentation and numerical modelling, giving practical guidance for designers and introducing the subject for researchers and graduate students.

Chapter 1  Hybrid structures in the real world

1.1 Introduction
1.2 Practical application of hybrid structures and context of the following chapters
References

Chapter 2 Load introduction and forcetransfer mechanisms at steel profile-concrete interface
Herve Degee and Rajarshi Das

2.1 Introduction
2.1.1 Bond stress
2.1.2 Scope of Chapter 2
2.2 General approach
  2.2.1 Experimental evidence from the SMARTCOCO research project
  2.2.2 General provisions for composite sections
2.3 Load introduction in hybrid components
  2.3.1 Shear stud connectors – force transfer
  2.3.2 Provisions for loaded composite sections
2.4 Longitudinal shear in hybrid components outside of the area of load introduction
  2.4.1 Provisions to deal with longitudinal shear 29
2.5 Resistance to longitudinal shear at the steel-concrete interface
2.6 Welded plates shear connectors
2.7 About strut-and-tie
2.8 Indirect support of a steel beam
  2.8.1 Experimental evidence from the SMARTCOCO project
  2.8.2 Interpretation of the results
  2.8.3 General model for indirect support
  2.8.4 Proposal of simplified design guidelines
2.9 Design examples
References

Chapter 3  Analysis of hybrid steel-concrete structures and components
Hugues Somja and Pisey Keo

3.1 Introduction
3.2 Scope
3.3 Analysis of structures and hybrid components
  3.3.1 General introduction
  3.3.2 Nonlinear analysis
    3.3.2.1 Global geometric imperfections
    3.3.2.2 Hybrid component imperfections
    3.3.2.3 Material constitutive model
  3.3.3 Linear elastic analysis
  3.3.4 First-order elastic analysis with amplification factors
  3.3.5 Second-order elastic analysis based on nominal stiffness
    3.3.5.1 Geometric imperfections
    3.3.5.2 Nominal stiffness
  3.3.6 Simplified method for slender hybrid components
    3.3.6.1 Resistance of cross-section
    3.3.6.2 Magnification factor
  3.3.7 Lateral torsional buckling
3.4 Background of the second-order elastic analysis based on nominal stiffness
  3.4.1 Introduction
  3.4.2 Finite element model
    3.4.2.1 Finite element formulation
    3.4.2.2 Hypothesis for finite element analysis for hybrid columns
    3.4.2.3 Validation of FE model
  3.4.3 Simplified second-order analysis of slender elements based on a moment magnification factor
    3.4.3.1 Component considered for the parametrical studies
    3.4.3.2 Understanding of the physical behaviour of hybrid columns
    3.4.3.3 Assessment of Eurocode 2 (2005) moment magnification method
    3.4.3.4 Assessment of the Eurocode 4 (2005) variant o the moment magnification method
    3.4.3.5 Synthesis of the parametric study
    3.4.3.6 Development of the hybrid-specific variant of the moment magnification method
3.5 A dedicated software for hybrid components: HBCOL
  3.5.1 Limitations of HBCOL
  3.5.2 Data interface
  3.5.3 Results
3.6 Design example
  3.6.1 Results of the nonlinear analysis
  3.6.2 Application of the simplified method for slender hybrid column
  3.6.3 Application of Eurocode 2
  3.6.4 Application of Eurocode 4
  3.6.5 Summary of the results at collapse level
References

Chapter 4 Hybrid walls and columns
André Plumier

4.1 Introduction
  4.1.1 Scope of Chapter 4   
  4.1.2 Positive characteristics of walls and columns with several embedded steel profiles
  4.1.3 A specific design issue: longitudinal shear at steel profiles-concrete interfaces
4.2 Load-deflection behaviour of reinforced concrete walls
  4.2.1 Characterization of load-deflection diagrams of reinforced concrete walls
  4.2.2 Components of a reinforced concrete wall deflection
    4.2.2.1 Flexural deformation
    4.2.2.2 Shear deformation
    4.2.2.3 Slip deformation
    4.2.2.4 Deformation of the anchorage block
    4.2.2.5 Sliding shear deformation
  4.2.3 Calculation of the total deformation of RC walls up to flexural yielding
    4.2.3.1 Calculation of flexure, slip and shear components of wall deformation at yield in flexure
    4.2.3.2 Calculation of wall deformation by means of an effective stiffness
  4.2.4 Calculation of the ultimate chord rotation θu of reinforced concrete walls
4.3 Calculation of shear action effects in hybrid walls and columns
  4.3.1 Introduction
  4.3.2 Classical beam model
  4.3.3 Elastic models taking into account shear deformation of sections
  4.3.4 Hybrid truss model
4.4 Calculation of the shear action effects in hybrid components by the elastic beam model
  4.4.1 Longitudinal shear at concrete-steel profiles interface
  4.4.2 Transverse shear in steel profiles
4.5 Calculation of the shear action effects in hybrid components by the hybrid truss model
  4.5.1 The hybrid truss model concept for the analysis of hybrid walls
  4.5.2 Shear stiffness KRC of the reinforced concrete truss
  4.5.3 Contribution of encased profiles to the stiffness KRC of compression struts: factor η
  4.5.4 Inclination θ of the compression struts in the calculation of KRC for design
  4.5.5 Shear stiffness KSP of the encased steel profiles
  4.5.6 Longitudinal shear action effects at the concrete-profile interfaces in hybrid walls
  4.5.7 Longitudinal shear by the beam method and by the hybrid truss method
  4.5.8 Contribution of encased steel profiles to the shear stiffness of walls
  4.5.9 Shear action effects in hybrid columns
4.6 Resistance of hybrid components to compression and bending
  4.6.1 Resistance to pure compression
  4.6.2 General method for assessing resistance to compression and bending
  4.6.3 Simplified method for assessing resistance to compression and bending
  4.6.4 Reduction of bending resistance by shear stresses 163
4.7 Resistance of hybrid components to shear 164
  4.7.1 Resistance to transverse shear 164
  4.7.2 Resistance to longitudinal shear at the steel-concrete interface
  4.7.3 Resistance of hybrid walls to transverse shear in static condition
  4.7.4 For a ductile behaviour of hybrid walls submitted to bending and transverse shear
  4.7.5 Combining reinforced concrete and encased profiles for resistance and ductility
    4.7.5.1 Conditions for the addition of resistance to shear of reinforced concrete and of profiles
    4.7.5.2 Condition on axial force for ductility of hybrid walls in bending
  4.7.6 Shear resistance of hybrid columns
4.8 Load introduction and anchorage zones
  4.8.1 B regions and D regions
  4.8.2 Introduction of horizontal forces in walls
  4.8.3 Introduction of vertical forces in walls
  4.8.4 Anchorage of steel profile
4.9 Experimental results and calculations
  4.9.1 Objectives of an overview of experimental results
  4.9.2 Bending stiffness αEcIg of hybrid walls or columns, from experiments to design
    4.9.2.1 Observations on the coefficient αEcIg deduce from tests on hybrid walls
    4.9.2.2 Bending stiffness of components for design
  4.9.3 Moment of resistance, transverse shear and ductility
    4.9.3.1 General conclusions from testing activity concerning the moment of resistance
    4.9.3.2 Tests on hybrid walls in Ji et al. (2010) and in Zhou et al. (2010)
    4.9.3.3 Tests on hybrid walls in Dan et al. (2011a)
    4.9.3.4 Tests on hybrid walls in Ji et al. (2015)
    4.9.3.5 Tests on hybrid walls at INSA Rennes in Degée et al. (2017)
    4.9.3.6 Tests on hybrid walls at ULiege in Degée et al. (2017)
    4.9.3.7 Tests on hybrid walls in Wu et al. (2018)
    4.9.3.8 Tests on hybrid walls in Zhang et al. (2020)
    4.9.3.9 Tests on hybrid walls in Zhou et al. (2021)
    4.9.3.10 Tests on hybrid columns in Bogdan et al. (2019)
  4.9.4 Longitudinal shear at steel profiles interface with concrete
4.10 Steel content in hybrid columns or walls
  4.10.1 Longitudinal steel
  4.10.2 Transverse steel
    4.10.2.1 General
    4.10.2.2 Confinement of boundary zones of wall
    4.10.2.3 Confinement around internal encased sections
    4.10.2.4 Concrete cover
4.11 Design examples for hybrid walls
  4.11.1 Moment M-axial force N interaction curve by the simplified method
    4.11.1.1 Geometrical data and strength properties of the wall
    4.11.1.2 Equivalent plates
  4.11.1.3 Squash load – pure compression – key Point A
  4.11.1.4 Plastic neutral axis and moment of resistance in pure bending – key Point B
  4.11.2 Resistance of a hybrid wall to combined shear, axial force and bending
    4.11.2.1 Hypothesis
    4.11.2.2 Design action effect
    4.11.2.3 Stiffness KRC of the reinforced concrete truss in the hybrid truss model
    4.11.2.4 Stiffness KSP due to steel profiles in the hybrid truss model
    4.11.2.5 Shear action effects in the hybrid truss model
    4.11.2.6 Limitation of tension strength of steel profiles due to shear stresses
    4.11.2.7 Design resistance under combined bending and axial force
    4.11.2.8 Design resistance in shear of reinforced concrete limited by crushing of concrete compression struts
    4.11.2.9 Design resistance in shear of reinforced concrete limited by yielding of the transverse reinforcement
    4.11.2.10 External profile. Design for resistance to longitudinal shear at concrete-profile interface 207
    4.11.2.11 Internal profile. Design for resistance to longitudinal shear at the concrete-profile interface 208
    4.11.2.12 Design for ductility 208
    4.11.2.13 Compliance with limitations of longitudinal steel content
  4.11.3 Calculation of longitudinal shear by the classical beam method


Chapter 5  Transition between composite and reinforced concrete components
Hervé Degée and Rajarshi Das

5.1 Introduction
5.2 Joint between a steel or composite coupling beam and a reinforced concrete wall relying on the embedded length
  5.2.1 Scope
  5.2.2 Definition of the required embedment length
  5.2.3 Design for static and low ductility applications
  5.2.4 Design for ductility
  5.2.5 Resistance of the embedded part of the steel profile
5.3 Connection of a steel or composite beam to a reinforced concrete column or wall without sufficient embedded length
  5.3.1 Design procedure
  5.3.2 Experimental evidence
5.4 Transition between composite and reinforced concrete columns
  5.4.1 Design procedure
  5.4.2 Experimental validation
5.5 Design examples
  5.5.1 Connection of a steel beam to a reinforced concrete column
  5.5.2 Transition zone from a composite to a reinforced concrete column
References


Chapter 6 Connections of reinforced concrete beams or flat slabs to steel columns using shear keys
Dan Bompa and Ahmed Elghazouli

6.1 Introduction
6.2 Common definitions and hypotheses
6.3 Connection of RC beams to steel columns through fully embedded shear keys
  6.3.1 Flexural strength
  6.3.2 Shear strength
    6.3.2.1 Composite region
    6.3.2.2 Transition regio
  6.3.3 Shear key design for hybrid connections to one-way components
  6.3.4 Validation and practical recommendations
  6.3.5 Design example
    6.3.5.1 Description of the structure
6.4 Connections of flat slabs to steel columns
  6.4.1 Flexural strength 304
  6.4.2 Punching shear strength 307
    6.4.2.1 Punching shear resistance of slabs without shear reinforcement
    6.4.2.2 Punching shear resistance of slabs with shear reinforcement
  6.4.3 Shear-head properties 312
  6.4.4 Validation and practical recommendations
  6.4.5 Design example – Connection of steel columns to flat slabs
    6.4.5.1 Description of structure
    6.4.5.2 Material properties
    6.4.5.3 Reinforcement design
Shear key design:
Embedment length:
Punching shear design
Shear key verification

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References