PRECASTG

Task for simulating/calculating all work steps and processes of the fabrication of a precast girder in a stressing bed (pretensioning) including heat cycles during curing

If the task PRECASTG is used in the construction of a precast template, then the assignment of the assembly is done via variables defined in the template. After calling up the tool Assemblies, a respective input window appears which is described in Assemblies for PRECAST.

Note: When using the task PRECASTG, the calculation results due to relaxation of the tendon in the stressing bed before the transfer of the prestress are stored in the prestressing load cases (see Calculation Options / Analysis) and not as usual in the load cases for the creep and shrinkage, because these are referred to the concrete elements and the concrete girder itself does not exist at that time.

Arguments

Time interval 1 [h]

Time from the beginning of the task until the stressing of the tendons (in hours)

Note: With this, the timeline of the task can be adapted by the hour since in the global construction schedule, tasks can only be defined by the day.

Time interval 2 [h]

Time from the stressing of the tendons until the casting of the concrete (in hours)

Time interval 3 [h]

Time from the casting of the concrete until releasing the tendons and thus transferring the force of the prestressing onto the precast girder (in hours)

Casting bed

Select a casting bed as defined in the menu Geometry/Placements for defining the boundary conditions of the fabrication

fcmtest (fcm test)

Input the mean concrete compressive strength from the measurement

Important note: If this input is missing, the real concrete age (at the end of the task PRECAST) is taken for evaluating fcm.

Dshrink (D shrinkage)

Optionally input the (fictitious) age of the concrete at the beginning of the drying shrinkage (in days)

If this input is missing, Dshrink =0.

It is recommended to evaluate this value automatically by activating the checkbox Automatic. In doing so, using the value fcmtest, at the time of the measurement (end of time interval 3) the fictitious concrete age is evaluated which is the basis for calculating the drying shrinkage.

Stress group

Name of the stress group containing the tendon stressing to be applied

Note: When using the task PRECAST within a precast template, this definition is best done by means of variables.

On the left side of the window, there is a schematic display of the fabrication process with all relevant parameters. Note that if the assignment of an assembly is missing (which is the case when using the task PRECAST within a precast template), no material is assigned and thus, some values can not (or not properly) be calculated. Therefore, there is an additional possibility for selecting a material for the graphical display under Preview which can be selected based on the material assignments in the Constructions or directly from the defined materials in the menu Materials.

Under View you can set the font size of the texts in the graphical display.