Bracing design requirements for inelastic members
Abstract
Using properly spaced and designed bracing can substantially increase the
buckling capacity of a member. A brace needs to satisfy both stiffness and strength
requirement. Significant research has been done for the bracing requirements of
elastic members. Relatively little work has been performed for the bracing design of
inelastic members.
This research focuses on the brace design requirements for structures that rely
on plastic redistribution or energy absorption. The finite element analysis results for
lateral bracing behavior in inelastic beams are presented. The research focuses on the
lateral bracing requirements to achieve a specified rotation capacity in braced
members subjected to uniform moment and moment gradient. The brace stiffness and
lateral brace force requirements for inelastic steel members are evaluated considering
the effects of unbraced length, flange slenderness and web slenderness. The results
show that the current AISC-LRFD requirements for brace stiffness are adequate and
not sensitive to rotation capacity. Brace forces, however, increase as rotation capacity
increases. Brace forces also increase significantly when local flange and web
buckling occur. The factors affecting beam rotation capacities and lateral brace
forces are discussed. A design formula for beam rotation capacities is proposed.
The lateral bracing behavior of inelastic beams under cyclic loading were
investigated both experimentally and analytically. The bracing requirements for
inelastic columns were also considered.
Description
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