Add stirrup update strategy

StructureHelperCommon/Models/Forces/IFactoredForceTuple.cs

@@ -1,4 +1,5 @@
-using System;
+using StructureHelperCommon.Infrastructures.Interfaces;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -6,9 +7,15 @@ using System.Threading.Tasks;
 
 namespace StructureHelperCommon.Models.Forces
 {
-    public interface IFactoredForceTuple
+    public interface IFactoredForceTuple : ISaveable, ICloneable
     {
+        /// <summary>
+        /// Combination of internal forces for bar
+        /// </summary>
         IForceTuple ForceTuple { get; set; }
+        /// <summary>
+        /// Properties of combination of forces
+        /// </summary>
         IFactoredCombinationProperty CombinationProperty { get; set; }
     }
 }