Norma Europea

A cement and concrete industry publication

Properties of Concrete for use in Eurocode 2
How to optimise the engineering properties of concrete in design to Eurocode 2
P.Bamforth BSc (Hons) PhD C Eng MICE D.Chisholm BE (Hons) CPEng IntPE(NZ) J.Gibbs BA MICT T.Harrison BSc PhD C Eng FICT MICE

Properties of concrete for use in Eurocode 2
Contents
Symbols 1. 2. 3. 4. 5. 6. 7. 8. 9.Introduction Assumptions underlying Eurocode 2 Compressive strength Tensile strength Bond strength Modulus of elasticity Tensile strain capacity Creep Shrinkage ii 1 4 5 11 17 19 24 26 30 35 37 38 39 42 45 47 48 51

10. Thermal expansion 11. Thermal conductivity 12. Specific heat 13. Fire resistance 14. Adiabatic temperature rise 15. Durability 16. The use of recycled aggregates References Appendix ASymbols
c cp cv D Ec Ecd Ec,eff Ecm fbd fcd fcd,fat fck fck,c fck,cube fcm fcm,cube fctd fctk fctm fctm,sp fctm,fl fct,sp fcu s sr,max t α αc αcc αct βcc(t) γc γcE γm εca(t) εca(∞) εcc (∞,t0) εcd εcs εctu η1 η2 cover to reinforcement specific heat coefficient of variation thermal diffusivity tangent modulus design value of modulus of elasticity of concrete effective modulus of elasticity ofconcrete mean secant modulus of elasticity of concrete ultimate (design) bond stress design compressive strength design fatigue strength specified characteristic cylinder compressive strength confined characteristic compressive strength specified characteristic cube compressive strength mean concrete cylinder compressive strength mean concrete cube compressive strength design tensile strengthcharacteristic axial tensile strength of concrete mean axial tensile strength mean splitting tensile strength mean flexural tensile strength tensile splitting strength specified characteristic cube compressive strength (BS 8110 term) coefficient for cement type used with the age function crack spacing time coefficient applied to age function coefficient of thermal expansion coefficient for long-term and loadingeffects on compressive strength coefficient for long-term and loading effects on tensile strength age function for strength partial safety factor for strength of concrete partial safety factor for strength of concrete used with Ecm partial safety factor for strength of a material autogenous shrinkage strain up to time t autogenous shrinkage strain at time t = ∞ creep deformation at time t = ∞ dryingshrinkage strain total shrinkage strain tensile strain capacity coefficient related to bond condition coefficient related to bar diameter

ii

λc ρ ρp,eff f φ (∞, t0) σc

thermal conductivity density ratio of area of reinforcement to effective area of concrete bar diameter creep coefficient at time t = ∞ constant compressive stress applied at time t = t0

iii

Introduction

1.Introduction
In the design of concrete structures, engineers have the flexibility to specify particular concrete type(s) aimed at meeting the specific performance requirements for their project. For instance where calculated deflections exceed serviceability limits, the designer can achieve lower deflections by increasing the class of concrete and the associated modulus of elasticity, rather than by resizingmembers. With this flexibility goes the responsibility for ensuring that the quality control in concrete production and subsequent site operations will enable the concrete as cast to meet the specified requirements in service. Typically concrete is specified by compressive strength class, which indicates the characteristic compressive strength required. However, in design, a range of properties ofconcrete are used that are not normally part of the concrete specification. These may relate to both structural integrity and serviceability. BS EN 1992-1-1, (Eurocode 2: Design of concrete structures, Part 1-1 – General rules and rules for buildings) Section 3: Materials details these properties which are generally assumed to be related to the cylinder compressive strength, expressed either as the...