Protected Function creaDtVacio(ByVal dt As DataTable, ByVal tam As Integer) As DataTable Implements IGestionEmpresa.creaDtVacio
        Try
            Dim dtvacio As New DataTable
            For j As Integer = 0 To dt.Columns.Count - 1
                dtvacio.Columns.Add(dt.Columns(j).ColumnName)
            Next

            For i As Integer = 0 To tam
                Dim dr As DataRow
                dr = dtvacio.NewRow
                dtvacio.Rows.Add(dr)
            Next

            Return dtvacio
        Catch ex As Exception
            Throw ex
        End Try
    End Function

Funcion que crea un datatable vacio.  Util para llenar un gridview. Ej. grvConvenio.DataSource = creaDtVacio(dtMiTabla, 3)
Significa que el gridview sera llenado con la estructura del datatable "dtMiTabla" con 3 filas vacias asignadas

Crear datatable vacio

VB.NET