When intervening in existing buildings, floor removals and creating new floor openings for stairs and elevators are a common practice. However, people often underestimate the importance of lateral bracing and the role it plays in the capacity of the vertical supports of the building (walls, columns, etc.). Increasing the distance between the lateral braces of a column, by removing an intermediate floor for example, decreases its capacity exponentially. For instance, increasing the distance of the lateral bracing from 10 to 20 feet reduces the capacity of the column to about one-quarter of its original value. (Euler is the one to blame for finding this out).
At OSE we are well aware of the importance of the lateral bracing and this picture is a good example of it; the lateral bracing previously provided by the floor is now provided by steel channels located on both sides of the columns and through-bolted along the column height. The channels were installed before the floor was removed so that bracing was provided at all times, reducing additional costs in temporary bracing during demolition.
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