diff --git a/StructureHelperLogics/NdmCalculations/Cracking/RebarStressCalculator.cs b/StructureHelperLogics/NdmCalculations/Cracking/RebarStressCalculator.cs
index aca6206..52f0c5f 100644
--- a/StructureHelperLogics/NdmCalculations/Cracking/RebarStressCalculator.cs
+++ b/StructureHelperLogics/NdmCalculations/Cracking/RebarStressCalculator.cs
@@ -73,7 +73,7 @@ namespace StructureHelperLogics.NdmCalculations.Cracking
             var strainMatrix = TupleConverter.ConvertToLoaderStrainMatrix(strainTuple);
             result.RebarStrain = stressLogic.GetSectionStrain(strainMatrix, rebarNdm);
             result.RebarStress = stressLogic.GetStress(strainMatrix, rebarNdm);
-            result.ConcreteStrain = concreteNdm.Prestrain;
+            result.ConcreteStrain = - concreteNdm.Prestrain;
         }
 
 
diff --git a/StructureHelperLogics/NdmCalculations/Cracking/TupleCrackCalculator.cs b/StructureHelperLogics/NdmCalculations/Cracking/TupleCrackCalculator.cs
index 2536626..c388607 100644
--- a/StructureHelperLogics/NdmCalculations/Cracking/TupleCrackCalculator.cs
+++ b/StructureHelperLogics/NdmCalculations/Cracking/TupleCrackCalculator.cs
@@ -90,7 +90,7 @@ namespace StructureHelperLogics.NdmCalculations.Cracking
                 longLength = GetLengthBetweenCracks(longElasticStrainTuple);
                 shortLength = GetLengthBetweenCracks(shortElasticStrainTuple);
             }
-            CalcCrackForce();
+            //CalcCrackForce();
             //for (int j = 0; j < 100000; j++)
             //{
                 result.RebarResults.Clear();