Commercial manufacturing of open web joists began in 1923. With a modern day average of over 1,000,000 tons produced each year in North America, there are millions of joists currently in service.
The need to modify or reinforce existing joists is growing exponentially each year. More and more building renovations are planned or underway, with roof top units being added or moved, monorail or crane loads and conveyors being introduced, or simply the need to repair owner/tenant caused damage to joists.
The full process from joist investigation to joist evaluation will include:
* identifying key characteristics of in-place joists
* how to determine the capacity of existing joists
* evaluate the joists for the new loads
* identifying the joist components and connections that are inadequate
Several examples will be presented relating to:
* when and how to reinforce joists
* shortening and lengthening joists
the relative costs of repair, and when to consider adding new joists or beams
* how to design reinforcement of tension and compression web members
* top chord and bottom chord reinforcement methods