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Modulus of elasticity changing over time

SCIA Engineer enables the users to apply several approaches when analysing construction stages:

• Use the standard solver and calculate the construction stages without any effect of time. Only a sequence of individual models was analysed and the internal forces changed according to changing boundary conditions.

• Use TDA (Time Dependent Analysis) calculation in which the full process of aging is taken into account, including relaxation of the reinforcement, creep and shrinkage of concrete.

• Use the standard solver, but consider the change of modulus of elasticity (E) over time, i.e. aging of material, through a diagram that defines the changes of the modulus of elasticity over time (E-modulus diagram).

The latter can be equally applied to both frame and plate-wall structures.

In one project, the user may define several E-modulus diagrams. It is even possible that each material used in the project has its own E-modulus diagram. The E-modulus diagrams can be assigned to all or just some materials used in the project.

The procedure to use E modulus functions in the calculation

There are several prerequisites that must be met to allow for the calculation with changing E modulus.

Note: The procedure listed below is not a complete tutorial. It just emphasises operations that must be done in addition to standard steps that are done during the preparation and analysis of a structure.

The project must be of "Construction stages" type.

1. Open function Project from the main tree menu.

2. Set item Model to Construction stages.

3. Confirm with [OK].

The E modulus option must be selected in the Construction stages Setup dialogue

1. Open service Construction stages.

2. Start function Setup.

3. Set the Type option to E modulus function.

4. Confirm with [OK].

The E modulus function(s) must be defined

1. Open E modulus function manager:

   1. Use menu function Libraries > E modulus function,

   2. Use tree menu function Library > E modulus function.

2. Click button [New] to input a new E modulus function.

3. Define individual points of the function.

4. Confirm with [OK].

5. If required, repeat for as many E modulus functions as needed.

6. Close the manager.

Required materials must have the corresponding the E modulus function assigned

1. Open Material manager:

   1. Use menu function Libraries >Materials,

   2. Use tree menu function Library >Materials.

2. The list of material characteristics contains one additional item: E modulus function (Unless the option E modulus function is adjusted in the Construction stages setup, this item is not available).

3. Select the required material.

4. Select the appropriate E modulus function.

5. Repeat for as many materials as required.

6. Close the Material manager.

The Construction stages analysis must be run

1. Open the FE analysis dialogue:

   1. Use menu function Tree > Calculation, Mesh > calculation,

   2. Use tree menu function Calculation, Mesh > calculation.

2. Select Construction stage analysis option.

3. Start the calculation with [OK].

Note: Make sure that Beam settings and global time adjustments in individual construction stages correspond with the time used for the definition of the E modulus functions.

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