Construction Stage Analysis Control
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Enter the analysis conditions for a Construction Stage analysis. Define the final construction stage and select the analysis features among the features, which reflect the time dependent material properties and geometric nonlinearity. To achieve more accurate results for creep and shrinkage in a long duration construction stage, we may select the option of auto-generating steps.
The procedure for construction stage analysis is shown below.
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From the Main Menu select Analysis > Construction Stage Analysis Control. | ||||||||||||||||||||||||||||||
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Construction Stage Analysis Control dialog box
Final Stage
Assign a stage to be considered as the Final Stage of the construction stage analysis.
Last Stage
Other Stage
Analysis Option
Include Non-Linear Analysis Check to reflect the change of geometric shapes of the geometric nonlinear analysis in the construction stage analysis. Geometric Nonlinear analysis for Independent Stage Model cannot account for time dependent effects simultaneously. However, with Accumulative Geometric Nonlinear Stage Model, the program not only accounts for time dependent effects but also has an option to select the Pretension Type of cables and calculates tangential displacements while taking Lack of Fit Forces into account.
Independent Stage Geometric nonlinear analysis is carried out independently in models of each construction stage. This option is used for the backward analysis of a suspension bridge considering large displacement.
Accumulated Stage Geometric nonlinear analysis is carried out with accumulated effects of the models of each construction stage. This option is used for the forward analysis of a cable stayed bridge considering large displacement.
Include Time Dependent Effect Check to reflect the time dependent material properties such as the change of modulus of elasticity, creep and shrinkage in the construction stage analysis.
Time Dependent Effect
If Include Time Dependent Effect is checked on in the Analysis Option, enter the following information: Define the material properties related to creep and shrinkage in Time Dependent Material (Creep/Shrinkage).
Creep & Shrinkage
Type Select one of the options for considering creep and/or shrinkage.
Creep Convergence for Creep Iteration Specify the convergence requirement for ending the repetitive process in the analysis reflecting creep.
Number of Iterations: Maximum number of repetitions
Tolerance: for convergence
Only User's Creep Coefficient Perform the construction stage analysis only using the creep coefficients entered by the user. Creep coefficients are entered by elements in Creep Coefficient for Construction Stage.
Internal Time Steps for Creep Specify a number, which is used to divide a construction stage to create internal steps for considering creep.
Note Internal Steps are applied in the process of analysis, and the corresponding analysis results are not produced.
Auto Time Step Generation for Large Time Gap Specify a number, which is used to divide a construction stage to create internal steps when the duration of the construction stage is too long.
Note Internal Steps are applied in the process of analysis, and the corresponding analysis results are not produced.
Tendon Tension Loss Effect (Creep & Shrinkage) Check on to reflect the effect of prestressing tension loss of tendons due to creep and shrinkage. Define the tendon properties of the prestressing loss in "Tendon Property".
Variation of Comp. Strength Check on to reflect the change of modulus of elasticity related to the change of compressive strength of concrete. The maturity variant property is defined in "Time Dependent Material (Comp. Strength)".
Tendon Tension Loss Effect (Elastic Shortening) Check on to reflect the prestressing tension loss of tendons due to the elastic deformations of concrete.
Note Prestressing tension loss in tendons due to elastic deformations is caused by other loadings such as live loads, creep, shrinkage, prestressing other tendons, etc after the prestressing force is applied. Note that it is not the same as the elastic shortening loss, which is one of the instantaneous losses.
Non-linear Analysis
If Include Non-Linear Analysis is checked on in the Analysis Option, enter the following information:
Maximum
Number of Iterations/Load Step
Convergence
Criteria
Note step is {D1}, and the total displacement accumulated from each step is {D2}, the Norm is expressed as . If this value is smaller than the specified value, a convergence is considered to have occurred and the program stops the iterative analysis.
Cable-Pretension Force Control
Define the method of applying the pretension forces of cable elements.
Internal force: Apply the pretension forces as internal forces.
External force: Apply the pretension forces as external forces.
Add: Add external pretension forces to the pre-existing tension forces of cable elements.
Replace: Replace the pre-existing tension forces of cable elements with applied external pretension forces.
Note
Load Cases to be distinguished from Dead Load for CS Output
Dead Load is generally the most significant component of all the loads applied to construction stage analysis. The results of all the load cases except for Creep, Shrinkage and Relaxation of Tendons are lumped into CS: Dead Load. Here we can select certain load cases to be distinguished from the Dead Load and produce the results under CS: Erection Load.
Load Case: Select the Load cases to be distinguished from Dead Load
Load Type for CS:Erection Load: Specify a load type classified into CS:Erection, which is differently categorized from CS:Dead. This is effective when the Auto Generation function of Combinations is used. If the Auto Generation function is not used, it makes no difference which type will be selected.
: Add selected load cases to the list.
: Delete selected load cases from the list.
: Remove the conditions for a construction stage analysis. The construction stage analysis is not performed in this case.
Composite Section
If the Calculate Output of Each part option is selected, the construction stage analysis results of composite sections by each Part will be produced. The analysis result for each Part can be checked in Result >> Result Tables >> Composite Section for C.S..
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