Add checks for beam shear

StructureHelperLogics/Models/BeamShears/Logics/CheckStrategies/CheckStirrupsByDensityLogic.cs

@@ -0,0 +1,56 @@
+using StructureHelperCommon.Infrastructures.Interfaces;
+using StructureHelperCommon.Models;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperLogics.Models.BeamShears
+{
+    internal class CheckStirrupsByDensityLogic : ICheckEntityLogic<IStirrupByDensity>
+    {
+        private const int minDensity = 0;
+        private bool result;
+        private string checkResult;
+
+        public CheckStirrupsByDensityLogic(IShiftTraceLogger? traceLogger)
+        {
+            TraceLogger = traceLogger;
+        }
+
+        public IStirrupByDensity Entity { get; set; }
+
+        public string CheckResult => checkResult;
+
+        public IShiftTraceLogger? TraceLogger { get; set; }
+
+        public bool Check()
+        {
+            checkResult = string.Empty;
+            result = true;
+            if (Entity is null)
+            {
+                result = false;
+                string errorString = "\nStirrups by density is not assigned";
+                TraceMessage(errorString);
+            }
+            else
+            {
+                if (Entity.StirrupDensity < minDensity)
+                {
+                    result = false;
+                    TraceMessage($"\nStirrup {Entity.Name} density d = {Entity.StirrupDensity} must not be less than dmin = {minDensity}");
+                }
+            }
+
+            return result;
+        }
+
+        private void TraceMessage(string errorString)
+        {
+            checkResult += errorString;
+            TraceLogger?.AddMessage(errorString, TraceLogStatuses.Error);
+        }
+    }
+}