Concrete Material Dialog Box

The Concrete Material dialog box is used to define the material for either a column or a superstructure cross section.

To modify the concrete material for the cross section, click the Material button in the Multi-Cell CIP Box Section dialog box. To modify the concrete material for a pier definition, click the Material button for the column in the desired pier in the Pier and Column Definitions dialog box.

Unit Weight

Define the unit weight of the material.

E-Modulus, Ec

Define the 28-day modulus elasticity for the material.

Poisson's Ratio

Define Poisson's Ratio for the material.

fck

Define the 28-day compressive concrete strength for the concrete.

fci

Define the concrete strength at the time of post-tensioning.

Creep Strain

Calculate the ultimate creep coefficient or manually enter the values.

Humidity

Define the average humidity for the environment.

Residual Shrinkage

Calculate the ultimate shrinkage strain or manually enter the value.

Thermal Coeff

Define the coefficient of thermal expansion for the material.

Apply to All Superstructure Sections

Select to apply the values to all of the superstructure sections. This operation is a one-time only change.

Definitions

Setting	Description
Unit Weight	Unit weight is used in the calculation of self-weight dead load. This field defaults to 2,400 kg/m³.
Modulus Elasticity	This 28-day modulus of elasticity value is defined in the E-Modulus Ec_28d field. This value is used to calculate member stiffness, which in turn affects deflections, prestress losses, and resulting forces and stresses. By default, Ec is calculated per CHBDC.
Poisson's Ratio	Value of Poisson's Ratio is entered in the Poisson's Ratio field. This field defaults to 0.20.
Defining Compressive Concrete Strength (fck)	Value of the 28-day compressive concrete strength is entered in the fck_28d field. This field is used to calculate the allowable stresses for the Final condition
Defining Creep Strain	There are two options for calculating creep strain. By selecting the Calculate option, the program automatically computes the value per CHBDC. To manually input creep strain, select the User Input option and enter the desired value.
Initial Concrete Strength (fci)	Concrete strength is defined at the time of post-tensioning by entering the value in fcj_initial field. This value is used in calculating the allowable stresses for the Initial condition.
Humidity	Average humidity value is entered in the Humidity field. Average humidity is used in the calculation of creep, shrinkage, and prestress losses.
Thermal Expansion	Thermal expansion value of the material is entered in the Thermal Coeff field. This value affects temperature and temperature gradient load cases.
Applying Concrete Material Values to All Sections	To apply values you have entered to all sections of the structure, click the box next to the Apply to All Superstructure Sections option.
Calculating the Residual Shrinkage Strain	There are multiple options for calculating residual shrinkage strain according to CHBDC. shrinkage strain. By selecting the Calculate option, CIP RC/PT Girder automatically computes residual shrinkage strain according to CHBDC. To manually input the ultimate shrinkage strain, select the User Input option and enter the desired value.

Technical Discussion

For cross sections, the concrete material properties affect the loss of prestress through creep and shrinkage values, the allowable stress values based on code equations, and the shear and moment capacities based on code equations.

For piers, the concrete material properties for the substructure affect the response in the superstructure including the loss of prestress.

Nomenclature

Term	Definition
Apply to All Columns in the Pier	Apply the values to all of the columns in a pier.
Apply to all Superstructure Sections	Apply the values to all the superstructure sections.
Calculate	Automatically calculate the ultimate creep coefficient or the ultimate shrinkage strain of the material.
E-Modulus, Ec	The 28-day modulus elasticity for the material.
f'ck	The 28-day compressive concrete strength.
f'ci	The concrete strength at the time of post-tensioning.
Humidity	The average humidity for the environment.
Poisson's Ratio	The Poisson's Ratio for the material.
Thermal Coeff	The coefficient of thermal expansion for the material.
Unit Weight	The unit weight of the material.
User Input	Input a custom value for the ultimate creep coefficient or the ultimate shrinkage strain of the material.