5. Adding steel hoppers and staircases to existing structures

New steel staircases are frequently installed in existing buildings. It's a simple technique for changing traffic patterns without radical alterations to the building.

With the exception of pre-stressed concrete floors, all types of floor can easily be fitted with an additional steel hopper to accommodate a new staircase.

However, the right technique must be used to reinforce the existing structure according to its constituent materials, as illustrated in figure 63 for a reinforced concrete floor. For adequate reinforcement of the area affected by the breakthrough, the key parameters for this transformation are the size of the opening to be made and the joist spacing. This determines the amount of reinforcement to be applied to the adjacent...