Force combination was added

StructureHelperCommon/Models/Forces/DesignForceTuple.cs

@@ -0,0 +1,23 @@
+using StructureHelperCommon.Infrastructures.Enums;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Forces
+{
+    public class DesignForceTuple : IDesignForceTuple
+    {
+        public LimitStates LimitState { get; set; }
+        public CalcTerms CalcTerm { get; set; }
+        public IForceTuple ForceTuple { get; private set; }
+
+        public DesignForceTuple(LimitStates limitState, CalcTerms calcTerm)
+        {
+            LimitState = limitState;
+            CalcTerm = calcTerm;
+            ForceTuple = new ForceTuple();
+        }
+    }
+}