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Construction Stages, Creep Redistribution
The steps to create and handle construction stages
is described below.
Using a simple example, the calculation of creep
redistribution as a result of a system change is then explained with
the help of construction stages.
Construction Stages
Construction stages can be calculated for any
structure. For every construction stage a file is created for which
all calculation options are available. The systems and their
properties are 'inherited' from one construction stage to the next.
Redundant use of load cases and elements is prevented by the system.
The results of the individual construction stages can be combined
with or superposed over one another.
The following steps are taken to create construction
stages:
First fully enter the original system for the first
construction stage. The file name must end with (1), for instance
Bridge(1).FEM.
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In the file menu the function Construction stage...
is now active. In order to create the second construction
stage, choose this function and click New... The
second construction stage (here: Bridge(2).fem) is
automatically generated and activated. System changes or
expansions can now be introduced. The results from the
previous construction stages are available for load case
combination or superpositions.
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Using this method, you can create any number of additional
construction stages. The function Construction stage...
can be used to switch between the individual construction
statuses by double-clicking.
With New... a subsequent
construction stage is created from the active one. All
existing subsequent construction stages will be deleted. No
construction stage can be added retroactively.
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Example: Creep redistribution as a result of a system
change
The original system, construction stage 1, consists of 2
single-span beams with a length of 4.00 m and 6.00 m. Material: B25,
Section: T-beam.
For the original system the following is calculated:
Load case 1: Dead load
Load case 2: Creep t=10 to t=50
days, with phi.t = 0.66, creep-generated continuous load LC 1
Now the construction stage 2 is generated and the system changes
are implemented here. By removing the joint, a continuous model is
created. The additional load is placed on top of it and calculated:
Load case 3: Additional load 10 kN/m
The internal forces and deformations after 50 days result from
the dead load + creep 10/50 + the additional load:
Load case 4: Superposition LC 1, 2 and 3 (superposition of the
results)
The creep redistribution up to the final state is calculated by:
Load case 5: creep 1=50 to final state, phi.t=2.04,
creep-generated continuous load: LC 4
The final state results from load case 4 and 5:
Load case 6: final state (superposition LC4+LC5)
For comparison:
Monolithic
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