Does steel have a Poisson s ratio? Why is the Poisson s ratio of rebar larger than concrete

Some. Poisson's ratio:

French mathematician Simeom Denis Poisson is named.

The absolute value of the ratio of the transverse strain caused by the uniformly distributed longitudinal stress to the corresponding longitudinal strain within the proportional limit of the material. For example, when a rod is in tension, its axial elongation is accompanied by transverse contraction (and vice versa), and transverse strain e'The ratio to the axial strain e is called the Poisson's ratio v. The Poisson's ratio of a material is generally determined by test methods.

Poisson's ratio is the absolute value of the ratio of the transverse strain caused by the uniformly distributed longitudinal stress to the corresponding longitudinal strain within the proportional limit of the material. Note: When the proportional limit is exceeded, the Poisson's ratio changes with the change of stress, and is no longer actually a Poisson's ratio.

In this case, if the Poisson's ratio is recorded, the measured stress value should be indicated. For anisotropic materials, the Poisson's ratio varies with the direction of the applied stress.

Resources.

Generally speaking, the Poisson's ratio of steel is there, but the slenderness ratio of the steel bar itself is very large, and it is generally designed to be tensile or compressed, not sheared, so the Poisson's ratio does not need to be considered.

The introduction says the opposite, the Poisson's ratio of the steel bar is a little larger.

The Poisson's ratio is defined as the ratio of transverse and longitudinal strain, and has nothing to do with the modulus of elasticity.

Although the elastic modulus of steel is large, the difference between transverse and longitudinal deformation is small, so the Poisson's ratio is closer to 1 Concrete is a brittle material, and the deformation performance in both directions is different, and the Poisson's ratio is smaller.

Because concrete is more brittle than steel bar. And you have to grasp the definition of Poisson's ratio.

My intuition tells me that there must be some important scientific law behind this.

HPB300 light round steel density, thermal conductivity, Poisson's specific elastic modulus, 210 10 N mm. HPB300 round steel bar is a building material, and there is no shear modulus, thermal expansion coefficient, and specific heat index requirements.

The National Standard of the People's Republic of China "Code for the Design of Concrete Structures" GB 50010-2002 lists the elastic modulus of commonly used steel as follows:

hpb235(q235)：210000mpa；

HRB 335 grade bar, HRB 400 grade bar, RRB 400 grade bar, heat treatment bar: 200000MPa;

Stress-relieving steel wire (smooth steel wire, spiral rib steel wire, scored steel wire): 205000MPa;

Steel strand: 195000MPa.

Note: If necessary, the measured modulus of elasticity can be used for the steel strand.

Code for Design of Steel Structures GB 50017 2003 The elastic modulus is 206000MPa.

The Poisson's ratio is about.

The Poisson's ratio of steel is generally in the to.

This should be a number of this steel bar, because the specifications and models of different steel are different.

Reinforced concrete structure, steel bar belongs to the strength strengthening mechanism, and the cross-sectional area is small. In abaqus, this type of problem is widely simulated using the rebar mechanism. However, depending on the circumstances, other considerations may also be considered.

In Ansys, it is revealed that the material constants of reinforced concrete should be defined separately, and the elastic modulus of concrete C15 is to the 4th power.

c20c25

c30 3c35

c40c45

The modulus of elasticity of C50 steel bars is HPB235 (, HRB335, HRB400 (, Poisson's ratios are respectively, and the densities are 24 25kN m3, 7850

Then the two materials can be combined together, and the material constant of the rental ear of reinforced concrete cannot be defined in general.

The modulus of elasticity of reinforced concrete is determined according to what concrete is used, and the specification can be checked. For example, C60 is. Poisson's ratio is generally taken by one-sixth.

Hooke's law relation: l = fl ea, where the proportional constant e is called the elastic modulus, the value of e varies with the material, it is determined experimentally, and its value characterizes the ability of the material to resist elastic deformation. The EA is called the tensile (compressive) stiffness of the rod, and for tie rods of equal length and the same force, the greater the tensile stiffness, the smaller the deformation of the tie rod.

Rewrite the above equation as: l l = 1 f ea, let l l be the longitudinal line strain e, then the formula can become: e = normal stress e and transverse line strain e'A constant of the ratio to the absolute value of the longitudinal line strain e, which is called the transverse deformation factor or Poisson's ratio, denoted by v, whose value varies with the material and is also determined experimentally.

C30 concrete: ES=30GPA u=, can check the design code for concrete structures.

The elastic modulus is standardized, and the Poisson's ratio is generally one-sixth.