Add beam shear classes

StructureHelperLogics/Models/BeamShears/StirrupByDensity.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperLogics.Models.BeamShears
+{
+    public class StirrupByDensity : IStirrupByDensity
+    {
+        public Guid Id { get; }
+        public string Name { get; set; } = string.Empty;
+        public double StirrupDensity { get; set; }
+
+        public StirrupByDensity(Guid id)
+        {
+            Id = id;
+        }
+
+        public object Clone()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}