Add stirrup update strategy

StructureHelperCommon/Models/Forces/FactoredForceTuple.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Forces
+{
+    public class FactoredForceTuple : IFactoredForceTuple
+    {
+        public Guid Id { get; }
+        public IForceTuple ForceTuple { get; set; } = new ForceTuple();
+        public IFactoredCombinationProperty CombinationProperty { get; set; } = new FactoredCombinationProperty(Guid.NewGuid());
+
+        public FactoredForceTuple(Guid id)
+        {
+            Id = id;
+        }
+
+        public object Clone()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}