Effect of fi ller material on local and global behaviour of buckling-restrained braces

摘要

The nonlinear response of buildings has attracted a tremendous amount of attention in recent years. Braces,nas lateral force-resisting elements of a structure, are designed to not only react in the elastic region, butnalso to exhibit nonlinear response beyond the elastic limit. However, buckling in compression drasticallyndegrades the performance of braces under earthquake loading. Buckling restrained braces (BRBs) havenbeen evolved into very effective systems for severe seismic applications. They prevent buckling in compressionnthrough the encasing of core steel into a steel tube and confi ning infi ll concrete.nThe effect of infi ll material is investigated in this research through the use of experimental tests. Fillernmaterial may be concrete, grout or mortar, as well as granular material such as compacted aggregate.nMoreover, lightweight concrete or lean concrete may be utilized as fi ller to reduce the overall structuralnweight. Furthermore, the need for unbonding material may not arise when sand and gravel mixture is used.nNevertheless, the strength of the aggregate should be such that no buckling or strength deterioration isnobserved. Parametric studies on BRB characteristics are carried out in this research. Results of cyclicnloading tests are then provided for individual cases to characterize the effect of response parameters ofnBRB assemblages. Copyright © 2009 John Wiley & Sons, Ltd.