User Define

Function

• The user directly defines the time dependent material properties (creep, shrinkage and relaxation) of concrete. The properties are applied to Construction stage analysis and Heat of hydration analysis.
• Select "User Defined" as the Code in the Add/Modify Time Dependent Material (Creep/Shrinkage) dialog box and select the Creep Function and Shrinkage Strain Function defined here.
• Select User Defined as the Relaxation Coefficient in the Tendon Property dialog box and select the Relaxation Function defined here.

Call

From the main menu, select [Properties] tab > [Material Properties] group > [Time Dependent] > [User Define]

Input

Time Dependent Material Function dialog box

Click  under the tab being considered for data entry.

Click   to check or change or click  to delete the entered data. Click  to copy previously entered data.

Creep

Define the time dependent creep property of concrete material.

Function Name

Enter the name of Creep Function, which is referred to in the Add/Modify Time Dependent Material (Creep/ Shrinkage) dialog box if User Defined is selected in the Code field.

Creep Function Data Type

Select one of the Creep Function Data Types.

Specific Creep : Strain per unit stress excluding immediate deformation

Creep Function : Strain per unit stress including immediate deformation

Creep Coefficient : Ratio of creep strain to elastic strain

Elasticity

In midas Civil, when performing creep analysis, specific creep is used. The input creep coefficient is divided by the elastic modulus of the concrete specified here to calculate the specific creep. For more detailed information, please refer to the "Time-dependent Material" section in the Analysis Manual under Construction Stage Analysis.

Import

A frequently used Creep Function may be saved in and recalled from a file. The data file, fn.TDM retains the following form:

Scale Factor :  Multiplier for values

Graph Options : Check on for Log Scale graph

Description : Descriptive text for the Function

Add/Modify/Show Time Dependent Material Function dialog box

Shrinkage Strain

Define the shrinkage strain, which is a function of time.

Function Name

Enter the name of the function defining the change of creep strains, which is referred to in Shrinkage Strain Function of Add/Modify Time Dependent Material (Creep/ Shrinkage) dialog box when the Code is User Defined.

Import

A frequently used Shrinkage Strain Function may be saved in and recalled from a file, whose type is fn.TDM as for the Creep tab.

Scale Factor : Multiplier for values

Graph Options : Check on for Log Scale graph

Description : Descriptive text for the Function

1. If you have many elements in the Construction Stages with different activation age, then you must defined several creep functions with different loading ages.

2. If the loading age ( activation age of the element ) doesn’t match with any of the curve then an interpolation is done between two loading ages just more and less than the specified loading age.

Relaxation

Define the time dependent relaxation rate of prestressing tendon. The relaxation rate is based on the initial jacking force defined in Tendon Prestress Load. For the long-term relaxation loss, the program assumes the relaxation is constant after the final relaxation rate defined by the user.

Function Name : Enter the name of Relaxation Function, which is referred to in the Tendon Property dialog box if User Defined is selected in the Relaxation Coefficient field.

Option for Relaxation Time
Select one of the unit of horizontal axis of Relaxation Function Data.

Hour / Day

Import

A frequently used Relaxation Function may be saved in and recalled from a file. The data file, fn.TDM retains the following form:

Scale Factor : Multiplier for values

Graph Options : Check on for Log Scale graph

Description : Descriptive text for the Function