liminfoSAP2000 Reference
Free reference guide: SAP2000 Reference
About SAP2000 Reference
The SAP2000 Reference is a structured quick-lookup guide for CSI SAP2000, one of the most widely used structural analysis and design programs in civil and structural engineering. It covers the full range of element types including joint objects with restraints and springs, frame elements for beams, columns, and braces with end releases and insertion points, shell elements for slabs, walls, and decks in membrane, plate, shell, and layered configurations, cable elements for suspension and cable-stayed bridges, link elements for isolators, dampers, and gap connections, and solid elements for mass concrete structures.
The reference documents all major load pattern types: dead loads with self-weight multipliers, moving loads with KL-510 vehicle classes and multi-lane reduction factors, temperature loads with uniform and gradient profiles, prestress loads with parabolic tendon layouts and friction/anchorage/long-term losses, response spectrum functions for KDS 41 17 seismic design with CQC modal combination, time history earthquake inputs, and load combinations for ultimate and service limit states. Analysis capabilities span linear static, modal (eigenvector and Ritz vector methods), buckling, nonlinear static pushover with FEMA 356 hinges, and nonlinear direct integration time history with Newmark/HHT integration and Rayleigh damping.
Design check entries cover steel frame design per KDS 14 31 (AISC 360-16) with D/C ratios and P-M interaction, concrete frame design per KDS 14 20 (ACI 318) with Pu-Mu interaction diagrams, the bridge design wizard for PSC box and steel I-girder bridges, and the Section Designer for arbitrary composite cross-sections with P-M-M interaction diagrams. Result output features include force/stress visualization, contour plots, table export to Excel/CSV, mode shape and time history animations, and the SAP2000 OAPI programming interface for automation.
Key Features
- Six element types: joint, frame, shell, cable, link, and solid with all property and release options
- Moving load definition with KL-510 standard truck, lane width, and influence line auto-calculation
- Response spectrum and time history seismic analysis setup with KDS 41 17 design spectra
- Prestress load modeling with parabolic tendon layout, friction, anchorage slip, and long-term losses
- Modal analysis with eigenvector and Ritz vector methods plus 90% mass participation verification
- Nonlinear pushover and direct integration time history analysis with P-Delta and large displacement
- Steel and concrete frame design checks per AISC 360-16 and ACI 318 with D/C ratio output
- SAP2000 OAPI (Open Application Programming Interface) Python automation code examples
Frequently Asked Questions
What element types does SAP2000 support?
SAP2000 supports joints (nodes with restraints, masses, and springs), frame elements (2-node linear elements for beams/columns/braces), shell elements (membrane, plate, shell, or layered for slabs/walls/decks), cable elements (tension-only for suspension bridges), link elements (linear springs, dampers, isolators, gaps, hooks), and solid elements (8-node hex for 3D mass concrete analysis).
How do I define a response spectrum for seismic analysis?
Go to Define > Functions > Response Spectrum and select the KDS 41 17 design response spectrum. Input the effective acceleration (e.g., S=0.22g), site coefficients Fa and Fv, and a damping ratio of 5%. Set the modal combination method to CQC (Complete Quadratic Combination). Then assign the spectrum to a load case under Define > Load Cases.
What is the difference between eigenvector and Ritz vector modal analysis?
Eigenvector analysis finds exact natural frequencies and mode shapes but may require many modes. Ritz vector analysis is generally more efficient because it targets modes that are most relevant to applied loads. Both methods should achieve a mass participation ratio sum greater than 90%. Ritz vectors are recommended when load-dependent response is important.
How do I set up a pushover analysis in SAP2000?
Define a gravity load case first (e.g., 1.0D + 0.25L), then create a Static Nonlinear load case with lateral push proportional to the first mode or uniform distribution. Assign plastic hinge properties per FEMA 356 to frame elements. Run the analysis to obtain the capacity curve (base shear vs. roof displacement) for performance evaluation.
How does SAP2000 handle bridge design?
The Bridge Wizard (Bridge > Bridge Wizard) guides you through span layout definition, superstructure types (PSC box, steel I-girder), and section properties. SAP2000 can perform construction stage analysis, apply moving loads with automatic influence line calculation, and evaluate code-based design checks for bridge components.
What design codes does SAP2000 support for steel and concrete?
For steel frame design, SAP2000 supports KDS 14 31 (equivalent to AISC 360-16) with D/C ratio checks, unbraced length calculations, effective length factors, and P-M interaction equations. For concrete frame design, it supports KDS 14 20 (ACI 318) with Pu-Mu column interaction diagrams, beam tension reinforcement (As), and shear reinforcement (Av/s) calculations.
What is the Section Designer used for?
The Section Designer (Define > Section Properties > Section Designer) allows you to create arbitrary cross-sections of any shape, including composite sections combining concrete and steel. It automatically computes the P-M-M interaction diagram and effective section properties (EI, EA) used in analysis and design checks.
Can SAP2000 be automated through an API?
Yes, SAP2000 provides the OAPI (Open Application Programming Interface) that can be accessed through Python, VB.NET, C#, or MATLAB. You can create models, assign properties, run analyses, and extract results programmatically. The reference includes a Python example using comtypes.client to initialize a new model.