A Numerical Investigation of Erection Bridging in Double-Pitched Open-Web Steel Joists

Open-web steel joists are truss members used to support roofs and floors in steel buildings. They are commonly used because they are lightweight and inexpensive to manufacture on a large scale but have a large load carrying capacity due to their depth. Because of this depth, these joists are very unstable laterally, which is addressed by adding bridging (horizontal or diagonal) members between them to resist rotation of the joists. One of the bridging types is erection bridging, which is used to prevent a joist from buckling laterally while steel erectors are traversing it during construction. The current erection bridging requirements do not include provisions for double-pitched joists, which have dual-sloped top chords and flat bottom chords. These joists have the potential to be much more unstable than flat joists due to changes in depth over their length, which can cause serious safety concerns if they are not bridged properly. The purpose of this project was to determine the erection stability of double-pitched joists. This project utilized finite element modeling to determine the stability of a variety of double-pitched joists under the erection loads. The results of this research include an analysis of the behavior of double-pitched joists under the load of an erector without bridging, and recommendations for corrections to the current bridging requirements that would adjust them to include double-pitched joists.