Bentley Communities
Bentley Communities
  • Site
  • User
  • Site
  • Search
  • User
  • Welcome
  • Products
  • Support
  • About
  • More
  • Cancel
RAM | STAAD | ADINA
  • Product Communities
  • More
RAM | STAAD | ADINA
RAM | STAAD | ADINA Wiki RAM SS Polygon Intersection Error [TN]
    • Sign in
    • Working Remotely with RAM or STAAD
    • -RAM | STAAD | ADINA Wiki
      • +Integrated Structural Modeling
      • +Limcon
      • +Microstran
      • +MStower
      • +RAM Concept
      • +RAM Connection
      • +RAM Elements
      • +RAM SBeam
      • -RAM Structural System
        • +Known Issues in Ram Structural System
        • +RAM Structural System - Feature Articles
        • +RAM Structural System Release Notes
        • -RAM Structural System Support Solutions
          • ISM menu is missing under the File Menu
          • -RAM Structural System - General Topics
            • +Installation - RAM Structural System
            • +Licensing - RAM Modeler
            • New Workflow for tables in RAM Structural System Version 14.06
            • +RAM Defaults Guide [TN]
            • +Ram Manager Errors
            • +RAM SS - Modules Overview
            • +RAM SS 3D Viewer FAQ
            • +RAM SS Common Framing Table Errors [TN]
            • RAM SS File-Open Troubleshooting [TN]
            • RAM SS Files [FAQ]
            • +RAM SS Installation [FAQ]
            • RAM SS Manager Notes
            • RAM SS Polygon Intersection Error [TN]
            • RAM SS Printing
            • RAM Structural System File Does Not Convert and Open - GetNextUniqueID
            • RAM Table Editing [FAQ]
            • RAMSS Two Way Decks [TN]
            • Unable to display notifications
            • Why do columns fail to display in 3D View?
          • +RAM Structural System - RAM Concrete
          • +RAM Structural System - RAM Foundation
          • +RAM Structural System - RAM Frame
          • +RAM Structural System - RAM Modeler
          • +RAM Structural System - RAM Steel
          • +RAM Structural System Tutorial
          • +What is RAM DataAccess? [TN]
        • RAM Structural System V17.0 License Consolidation
      • +Scenario Services
      • +STAAD Advanced Concrete Design (RCDC)
      • +STAAD RCDC FE
      • +STAAD Foundation Advanced
      • +STAAD.building
      • +STAAD.offshore
      • +STAAD.Pro
      • +Structural Analysis Support Solutions
      • +Structural Dashboard
      • +Structural WorkSuite
      • Structural Synchronizer Links
    • +Webinars
    • +RAM | STAAD Learning Resources

     
     Questions about this article, topic, or product? Click here. 

    RAM SS Polygon Intersection Error [TN]

      Product(s): RAM Structural System; Ram Steel
      Version(s): Any
      Environment:  All
      Area:  Analysis; Framing Tables

    Error in Polygon Intersection

    The message, “Error in polygon intersection” is fairly general, and could be indicative of several different conditions related to the geometry of a RAM SS model. Several polygons exist on any floor plan such as:

    • surface loads
    • snow loads
    • areas of deck

    The program also defines some internal polygons when calculating tributary areas of individual members. We call these

    • “beam loops”

    A polygon error may occur at various stages of the modeling and design, specifically during any of the following events: 

    • data check in the Modeler 
    • building of the “Framing Tables” at the start of any design module 
    • building the “Frame Data” in RAM Frame 
    • analyzing Wind loads in RAM Frame.

    Modeler - Data Check

    When a polygon error occurs while running the data check, the modeler will terminate. This should not cause you to lose any recent changes, however.

    One possible cause for such an error is the presence of zero-length beams or walls in the model. These members cannot be seen, but the numbers can be displayed. If you see beam numbers with no associated beams or overlapping beam numbers, this will help in locating the problem. You can then delete these beams with a fence. The beam numbers should then disappear as confirmation.

    Under normal circumstances, zero-length beams cannot be modeled, but they can be imported from DXF or Revit, or they can sometimes result from modifications to the grids after the beams have been modeled.

    Beam or Column Design - Framing Tables

    When any design module is initiated, the program starts by “Building the Framing Tables”. During the process, the program goes through the beam loops one at a time to determine the tributary loads. If a polygon error occurs while the framing tables are being built, the user can identify the beam number and coordinates together with the floor type where the program stopped processing information. This information can be helpful in locating the source of the error.

    The polygon error may be followed by a second error message saying, “SetLineEq() passed two identical points at 0.00 0.00”.

    This usually indicates a problem with the shape of the beam loop. For example, if there is only one beam connected to an interior column within the deck area, a polygon error will arise for one of the members in that immediate vicinity:

    A second type of message saying, “Clipping a degenerate polygon” or “Too many intersection points” indicates a different type of polygon error.

    The error in this case may be due to internal numerical accuracy, especially when the beams or polygons in that area are ever so slightly skewed in plan.

    This type of error is often caused from having multiple, overlapping surface loads or decks. The program only counts the top-most layer of surface loads when analyzing a structure, but it must make a determination about what load is "on top" by comparing the areas of the various overlapping surface load polygons as they were applied. When multiple layers of loading are used, this calculation becomes more complex.

    The program may give an error when only a tiny sliver of one load overlaps another, or if the edge of a surface load polygon is very slightly off of a beam line. In this case, it is necessary to delete and re-apply that surface load in a different area. The more complicated the beam loops, the more likely a polygon error will occur.

    In the example below, the end coordinates of beam 113 did not match the end of beam 108 or the column in that location creating a tiny polygon for the program to deal with. Furthermore, the surface load also angles just slightly away from beam 98.

    To solve the problem in this case, beam 113 was adjusted to match the column coordinates and the surface loads were recreated.

    Tip: It may be necessary to save the file under a test name and systematically eliminate load and deck polygons from the file until it works, then return to the original file and rework the problem area only. When laying out deck or surface load polygons, first turn off all the unnecessary snap points. Typically the only snap point needed are Columns, Beam Ends, and Wall Ends:

    RAM Frame – Building Frame Data

    After the framing tables are finished, the RAM Frame program goes through a second step of constructing the Frame Data. During this phase the program determines the diaphragm masses and the gravity for notional loads of each diaphragm. This process is similar to the load calculations done during the framing tables, but slightly more complicated because the program is working with the larger polygon defined by the entire slab edge.

    Regretfully, the error in RAM Frame does not isolate the level type with the problem. In order to isolate the problem area the user should systematically remove stories from the story data until it works, then go back and examine the loads or decks on the problem level.

    RAM Frame – Analysis / Wind Exposure data

    If a polygon error occur near the end of the analysis in RAM Frame the issue is a little different. At this point the program is creating the polygons associated with the wind exposure. These shapes determine the total wind load tributary to any diaphragm and can be reported using Reports – Exposure boundaries.

    Typically the situation that causes this error is a complex slab edge that overlaps itself. Consider the geometry pictured below. If the inlet is 1’ wide and the program will function perfectly well when the slab edge overhang is less than 6” on each side, but once the overhangs are increased such that they meet or overlap problems can occur:

    RAM Concrete – Meshing Diaphragm

    Below is a polygon intersection that was produced when the diaphragms are meshed during the RAM Concrete Analysis. This error is associated with adjacent deck polygons with edges that are slightly skewed relative to each other. This slight skew results in a small area of several overlapping polygons. The problem floor level is identified in the Analysis Status window. The coordinates, defined in inches, are noted in the error message. This information is useful in locating the offending polygons.

    In the example below, the "48 Slab" and "16 Slab" deck areas snap to a deck vertex at the point marked in the screen capture. However, the top "48 Slab" area does not have a vertex at this point. Because the 3 nodes at the bottom edge of this polygon have slightly different y-coordinates, there is a slight skew and small overlapping zone near this area. Adding a deck vertex in the polygon representing the top "48 Slab" area at the point marked in the screen capture resolves the problem.

    See Also

    RAM SS Common Framing Table Errors [TN]

    • SELECTservices
    • RAM Structural System
    • TechNote
    • polygon
    • Framing Tables
    • errors
    • RAM Steel
    • Share
    • History
    • More
    • Cancel
    • Seth Guthrie Created by Bentley Colleague Seth Guthrie
    • When: Wed, Oct 1 2008 5:40 PM
    • Seth Guthrie Last revision by Bentley Colleague Seth Guthrie
    • When: Thu, Jul 12 2018 12:59 PM
    • Revisions: 18
    • Comments: 0
    Recommended
    Related
    Communities
    • Home
    • Getting Started
    • Community Central
    • Products
    • Support
    • Secure File Upload
    • Feedback
    Support and Services
    • Home
    • Product Support
    • Downloads
    • Subscription Services Portal
    Training and Learning
    • Home
    • About Bentley Institute
    • My Learning History
    • Reference Books
    Social Media
    •    LinkedIn
    •    Facebook
    •    Twitter
    •    YouTube
    •    RSS Feed
    •    Email

    © 2021 Bentley Systems, Incorporated  |  Contact Us  |  Privacy |  Terms of Use  |  Cookies