Add stirrup update strategy

StructureHelperCommon/Models/Forces/BeamShearActions/IBeamShearAction.cs

@@ -4,11 +4,23 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
+//Copyright (c) 2025 Redikultsev Evgeny, Ekaterinburg, Russia
+//All rights reserved.
+
 namespace StructureHelperCommon.Models.Forces
 {
+    /// <summary>
+    /// Implements properties of force at the and of bar
+    /// </summary>
     public interface IBeamShearAction : IAction
     {
-        IBeamShearAxisAction XAxisShearAction { get; }
-        IBeamShearAxisAction YAxisShearAction { get; }
+        /// <summary>
+        /// External force at the end of bar
+        /// </summary>
+        IFactoredForceTuple ExternalForce { get; }
+        /// <summary>
+        /// Internal loads on bar
+        /// </summary>
+        IBeamShearAxisAction SupportAction { get; }
     }
 }