김경종
66 lines
2.6 KiB
Markdown
66 lines
2.6 KiB
Markdown
---
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type: concept
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title: "Midas Civil Buckling P-Delta and Geometric Nonlinearity"
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created: 2026-06-02
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updated: 2026-06-02
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address: c-000163
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aliases:
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- MIDAS Civil buckling
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- midas Civil P-Delta
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- midas Civil geometric nonlinearity
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tags:
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- concept
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- finite-element-method
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- midas-civil
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- buckling
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- nonlinear-analysis
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status: current
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related:
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- "[[Midas-Civil-Analysis-Reference|Midas Civil Analysis Reference]]"
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- "[[midas Civil]]"
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- "[[Geometric Stiffness Matrix]]"
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- "[[Static Equilibrium Equation Solvers]]"
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- "[[Nonlinear Finite Element Analysis]]"
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sources:
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- "[[Midas-Civil-Analysis-Reference|Midas Civil Analysis Reference]]"
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source_refs:
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- source: "[[Midas-Civil-Analysis-Reference|Midas Civil Analysis Reference]]"
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raw_path: ".raw/MidasCivilAnalysisReference/"
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raw_files:
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- "MidasCivilAnalysisReference_024.md"
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- "MidasCivilAnalysisReference_033.md"
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- "MidasCivilAnalysisReference_025.md"
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- "MidasCivilAnalysisReference_031.md"
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md_indices:
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- 24
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- 33
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- 25
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- 31
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match: "heuristic-heading-keyword"
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confidence: high
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---
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# Midas Civil Buckling P-Delta and Geometric Nonlinearity
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## Definition
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Midas Civil buckling, P-Delta, and geometric nonlinearity are the stability-related procedures that account for axial-force-dependent stiffness, displaced geometry, and critical load factors.
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## How It Works
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The analysis reference separates linear buckling from nonlinear geometric effects. Buckling analysis is an eigenvalue-style procedure for critical load factors and buckling shapes. P-Delta analysis captures second-order force effects from axial loads acting through lateral displacements. More general geometric nonlinearity requires incremental equilibrium iterations because stiffness depends on the current configuration.
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## Solver Development Notes
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- Buckling requires a linear stiffness matrix, an initial-stress or geometric stiffness matrix, and an eigenvalue solver.
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- P-Delta should be treated as a second-order equilibrium correction, not as a postprocessing scale factor.
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- Geometric nonlinearity requires clear choices for tangent update, load stepping, convergence criteria, and force recovery.
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- Verification should include columns, frames, and bridge-pier examples where first-order and second-order responses diverge.
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## Connections
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- [[Geometric Stiffness Matrix]] is the common FE stability ingredient.
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- [[Static Equilibrium Equation Solvers]] provides the nonlinear iteration context.
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- [[Nonlinear Finite Element Analysis]] is the broader nonlinear analysis page.
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- [[Midas FEA Linear Dynamics and Buckling Analyses]] gives a detail-FE sibling reference.
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