CSiBridge Scheduler: Automatic Creation of Load Cases in Segmental Bridges
Analyzing bridges built by segmental balanced cantilever requires more than just defining geometry; it demands absolute control over the "time" dimension. The challenge isn't just sequencing segment additions, but isolating and analyzing critical intermediate structural states—such as the moment the cantilever reaches its maximum span before closure.
In this article, we focus on the Automatic Construction Scheduler feature in CSiBridge. We will see how this tool goes far beyond a simple Gantt chart: it is the engine that automatically generates independent Load Cases for specific construction stages.
This capability allows you, for example, to extract the stiffness and stress state of the structure at a precise construction moment and use them as a basis for modal, buckling, or wind analyses, without needing to create multiple separate models.
Video Demonstration
Watch the video for a complete demonstration of the workflow.
Step-by-Step
Step 1 — Definition of Base Geometry
We start by defining the parametric box girder section and the 100m Layout Line. It is upon this geometric base that the Scheduler will act to generate the construction sequence.
Watch the video at [00:28]
Step 2 — Span Assembly
We discretize the bridge into its logical components: Start Abutment, Pier (Bent) where segments will be added. Here we define the "raw material" the Scheduler will organize: pier tables, cast-in-place segments, and closure segments.
Watch the video at [00:45]
Step 3 — Prestressing and Form Travelers
We introduce the prestressing tendons and define the form travelers. The Scheduler will recognize these elements and automatically include them in the evolutionary analysis, applying the weight of the travelers at the tip of the cantilever and moving them as construction progresses—all automatically.
Watch the video at [02:24]
Step 4 — Scheduler Configuration and Precedences
We enter the Automatic Construction Scheduler. Here, we define the construction logic (cantilever symmetry) and adjust dependencies. The power of this tool lies in its ability to reorganize the entire structural analysis by simply changing one line in the Gantt chart—for example, forcing the execution of the abutments only after the completion of the central cantilever.
Watch the video at [03:21]
Step 5 — Creating Independent Load Cases
This is the crucial point of the video. Within the Scheduler's advanced settings, we use the "End Case Tag" functionality. By assigning this tag to the stage where the cantilever reaches its maximum span, we instruct CSiBridge to create an isolated Load Case that ends exactly at that moment.
Watch the video at [04:41]
Step 6 — Validating Generated Load Cases
After processing, we verify that the software has automatically created two distinct scenarios:
- An evolutionary load case running from the start up to the "End Case Tag" moment (maximum cantilever span).
- A second load case continuing from that point until the project's completion.
Watch the video at [05:03]
Step 7 — Application in Subsequent Analyses (Modal)
We demonstrate the practical utility of this separation: we configure a Modal Analysis to use the stiffness specifically from the Cantilever Load Case, and not from the final structure.
Watch the video at [05:39]
Step 8 — Results Analysis
We review the final results, observing the structure's behavior during the critical construction phase isolated by the Scheduler, validating the safety of the cantilever before the casting of the closure segment.
Watch the video at [06:05]
Conclusion
The CSiBridge Automatic Construction Scheduler is more than a planning tool; it is an analysis management tool. The ability to generate independent load cases via End Case Tags allows engineers to verify safety conditions in complex intermediate stages with speed and precision, eliminating manual stage configuration that is prone to errors.
If you are interested in this topic, we recommend consulting the article Staged Construction – Operación “Add Guide Structure”.
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