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Continuous Beam - Unexplained Reaction Values - Load = 10, Reaction = 15.9375

Oct 9, 2014 at 1:27 PM
I have been trying to analyse a 2 span continuous beam with an overhang.

A simple load of 10 produces the following reactions:
                             Fx Fy Fz 
Reaction Totals: N1 0 0 -4.0625
Reaction Totals: N2 0 0 0
Reaction Totals: N3 0 0 -13.75
Reaction Totals: N4 0 0 1.875
Reaction Totals: N5 0 0 0

Reaction Totals: TOT 0 0 -15.9375

Hi there,

I used the latest download and added the DoOneFrame(); function and called it.

Any ideas what I may be doing wrong? This has baffled me for a few days.

Cheers,
Paul


namespace BriefFiniteElementNet.CodeProjectExamples
{
class Program
{
[STAThread]
static void Main(string[] args)
{
  // Example2();
  // Example1();
  DoOneFrame();
}
// ...
private static void DoOneFrame()
{
  var Model = new Model();

  var N1 = new BriefFiniteElementNet.Node(0, 0, 0);
  N1.Label = "1";

  var N2 = new BriefFiniteElementNet.Node(2500, 0, 0);
  N2.Label = "2";

  var N3 = new BriefFiniteElementNet.Node(5000, 0, 0);
  N3.Label = "3";

  var N4 = new BriefFiniteElementNet.Node(10000, 0, 0);
  N4.Label = "4";

  var N5 = new BriefFiniteElementNet.Node(11500, 0, 0);
  N5.Label = "5";

  Model.Nodes.Add(N1);
  Model.Nodes.Add(N2);
  Model.Nodes.Add(N3);
  Model.Nodes.Add(N4);
  Model.Nodes.Add(N5);

  N1.Constraints =
      N2.Constraints =
          N3.Constraints =
              N4.Constraints =
                  N5.Constraints =
                      Constraint.FixedDY & Constraint.FixedRX & Constraint.FixedRZ;//DY fixed and RX fixed and RZ fixed

  N1.Constraints = N1.Constraints & Constraint.MovementFixed;
  N3.Constraints = N3.Constraints & Constraint.MovementFixed;
  N4.Constraints = N4.Constraints & Constraint.MovementFixed;

  BriefFiniteElementNet.Force ModelLoad = new BriefFiniteElementNet.Force(0, 0, 10, 0, 0, 0);
  N2.Loads.Add(new BriefFiniteElementNet.NodalLoad(ModelLoad));


  BriefFiniteElementNet.FrameElement2Node frameElement2Node;

  var secAA = SectionGenerator.GetISetion(0.24, 0.67, 0.01, 0.006);

  for (int NodeIndex = 0; NodeIndex < Model.Nodes.Count() - 1; NodeIndex++)
  {
    frameElement2Node = new BriefFiniteElementNet.FrameElement2Node(Model.Nodes[NodeIndex], Model.Nodes[NodeIndex + 1]);

    frameElement2Node.Geometry = secAA;
    frameElement2Node.E = 210E9;
    frameElement2Node.G = 210e9 / (2 * (1 + 0.3));
    frameElement2Node.UseOverridedProperties = false;
    frameElement2Node.Label = string.Format("e{0}", NodeIndex + 1);

    Model.Elements.Add(frameElement2Node);
  }

  Model.Solve();

  var r1 = N1.GetSupportReaction();
  var r2 = N2.GetSupportReaction();
  var r3 = N3.GetSupportReaction();
  var r4 = N4.GetSupportReaction();
  var r5 = N5.GetSupportReaction();

  Console.WriteLine(string.Format("Reaction Totals: N1  {0} {1} {2}", r1.Fx, r1.Fy, r1.Fz));
  Console.WriteLine(string.Format("Reaction Totals: N2  {0} {1} {2}", r2.Fx, r2.Fy, r2.Fz));
  Console.WriteLine(string.Format("Reaction Totals: N3  {0} {1} {2}", r3.Fx, r3.Fy, r3.Fz));
  Console.WriteLine(string.Format("Reaction Totals: N4  {0} {1} {2}", r4.Fx, r4.Fy, r4.Fz));
  Console.WriteLine(string.Format("Reaction Totals: N5  {0} {1} {2}", r5.Fx, r5.Fy, r5.Fz));

  var rt = r1 + r3 + r4 + r2 + r5;
  Console.WriteLine(string.Format("Reaction Totals: TOT {0} {1} {2}", rt.Fx, rt.Fy, rt.Fz));

  Console.WriteLine("DONE");
}
}
}
Coordinator
Oct 9, 2014 at 5:02 PM
Hi Paul,
Yes you are right, there was a bug in Node.GetSupportReactions() method. I've fixed the bug, can you please check again?

Regards