Fix beam shear force calculator

StructureHelperCommon/Infrastructures/Interfaces/IGetFactorLogic.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Infrastructures.Interfaces
+{
+    public interface IGetFactorLogic : ILogic
+    {
+        double GetFactor();
+    }
+}