Complex sentence: An interesting side note is that a freak tornado in Birmingham in 1996 damaged the wooden staircase, rather than remove and replace the stairs, the damaged state was repaired in situ resulting in the zig zag appearance.
Split into simpler sentences: An interesting side note is that a freak tornado in Birmingham in 1996 damaged the wooden staircase. Rather than remove and replace the stairs, the damaged staircase was repaired in situ resulting in a zig zag appearance.