Unintended Consequences of Exit Gate Signs

We were contacted by a client that had two steel columns busting through a concrete floor. The columns, which were intended to support some caution signs, were actually added after original construction at an exit to the parking structure. When the contractor installed the columns for the signs, they made sure that they were very strong and well connected at the tops and bottoms. Unfortunately, soil movement lifted the slab at the ground level, causing forces to transfer through the column up into the structural floor. The forces were so high that the steel column punched through the concrete slab, nearly severing a post-tensioned cable.

We performed the evaluation of the distress, designed a repair to the concrete slab, performed construction administration, and recommended that a vertical slip connection be provided at the top of the steel column if they really wanted to retain the column.