Serviceability Guidelines for Steel Structures

Serviceability limit states are conditions in which the functions of a building are disrupted because of local minor damage to or deterioration of building components or because of occupant discomfort. Many serviceability limit-states are the result of excessive structural deformations or motions. Current codes and standards used in steel design deal with the complex problems of serviceability limit-states with simple rules. Some of these rules have remained essentially unchanged for over a century. For the most part, they require only a check of deflections of the floor or frame under service load conditions. Thus, approach to serviceability presumes that a broad spectrum of building structure performance issues can be dealt with simply by means of static deflection checks. A closer look at serviceability issues is warranted by trends in modern construction. Changing architectural and building-use requirements, improvements in structural analysis and design made possible by the widespread use of computers, the use of lighter and less rigid cladding, uncoupling of nonstructural elements from the structural frame, the increasing use of high-strength steel leading to longer spans and bay sizes; all have resulted in building structural systems that are less stiff and massive. Such systems may deflect or vibrate excessively at service-load levels.