A+ à tousCells.UnMerge
Sub TEST()
Dim wb As Workbook
For Each wb In Workbooks
If wb.Name Like "Analyse*" Then
wb.Sheets("Concaténation").Select
Cells.Select
Cells.UnMerge
End If
Next wb
End Sub
Option Explicit
Sub Test()
Dim Wb As Workbook
For Each Wb In Workbooks
If Wb.Name Like "Analyse*" Then Wb.Sheets("Concaténation").Cells.UnMerge
Next Wb
End Sub