Fix beam shear force calculator

StructureHelperLogics/Models/BeamShears/Logics/IGetLongitudinalForceFactorLogic.cs

@@ -0,0 +1,15 @@
+using StructureHelperCommon.Infrastructures.Interfaces;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperLogics.Models.BeamShears.Logics
+{
+    public interface IGetLongitudinalForceFactorLogic : IGetFactorLogic
+    {
+        public double LongitudinalForce { get; set; }
+        public IInclinedSection InclinedSection { get; set; }
+    }
+}