public sealed class AssetType : ArcGIS.Core.CoreObjectsBase, System.IDisposable  

// Create edit operation
EditOperation editOperation = new EditOperation();
editOperation.Name = "Create structural attachment association";

// Create a RowHandle for the pole

Element poleElement = utilityNetwork.CreateElement(poleAssetType, poleGlobalID);
RowHandle poleRowHandle = new RowHandle(poleElement, utilityNetwork);

// Create a RowHandle for the transformer bank

Element transformerBankElement = utilityNetwork.CreateElement(transformerBankAssetType, transformerBankGlobalID);
RowHandle transformerBankRowHandle = new RowHandle(transformerBankElement, utilityNetwork);

// Attach the transformer bank to the pole

AssociationDescription structuralAttachmentAssociationDescription = new AssociationDescription(AssociationType.Attachment, poleRowHandle, transformerBankRowHandle);
editOperation.Create(structuralAttachmentAssociationDescription);
editOperation.Execute();