Performance Testing And Application Of Buckling-restrained Brace Building

Buckling restrained brace is a kind of structural member that not only can improvelateral stiffness of the structure,but also can dissipate seismic energy by inelastic deformationof the core. Usually,the cross section of the BRB’core is flat plate,crisscross,H-section andtubular-section, the buckling restrained mechanism is made out of reinforcedconcrete,concrete filled steel tube or steel. In many types of buckling restrained braces,theone made by crisscross core and concrete filled steel tube was widely used in construction.Choosing the buckling restrained brace with crisscross core and concrete filled steel tubebuckling restrained mechanism as the main object of study, the performance and applicationof buckling restrained braces were studied by experiments and structural examples in thispaper. The main contents and conclusions are as follows:(1)Three specimens was designed in this chapter.The length of the specimen was1600mm. The core of BRB is welded discontinuously by three steel plates. Hystereticcharacteristics of BRB is research by pseudo-static test, Skeleton curve characteristics, energydissipation capacity, ductility, uneven tension-compression characteristics, failure mode andbending residual deformation mode of BRB was analysed.Differences between designedperformance and testing performance was compared The influence of end rotation to theenergy-dissipation capacity was discussed.conclusions can be drew as follows: the designedperformance and testing performance of specimens was well matched,the hysteretic curve ofspecimen was symmetrical,tension capacity and compression capacity of specimen wasbalanced,the energy comsumption performance and ductility of specimens were basicallyreached application demands; the discontinuously welding of the core had a huge influence onthe failure mode and bending deformation of the specimen, the core of specimens wasruptured in two places,the bending deformation was mostly concentrated in the place withoutwelding; the end rotation had a negative influence on the energy-dissipation capacity of BRB,The equivalent viscous damping ratio will decreasing when the end rotation was inceased. (2)The finite element software ETABS was used to study six storey reinforced concreteframe structure retrofitted by BRB, seismic response of old structure and retrofitted structurein different seismic standards was analyzed, the results show that: story shear and storyoverturning moment was increased when the structure retrofitted by BRB, shear andoverturning moment sustained by columns was decreased when the structure retrofitted byBRB, the elastic and inelastic storey drift was decreased when the structure retrofitted byBRB. In medium and rare earthquake, the plastic hinge of structural members were decreasedand the damage of structural member was less.(3)The finite element software ETABS was used to study the method of replacing theconcentric brace in concentrically braced steel frame by buckling restrained brace. Threeprogrammes was designed according to the equal-stiffness principle and reduced-stiffnessprinciple. Seismic response of different structures were studied by mode-superpositionresponse spectrum method and static pushover analysis.The influence of buckling restrainedbraces to the internal force of column was researched. The results shows that: concentricbrace and buckling restrained brace can augment the frame stiffness,decrease the shears andoverturning moment of column as well as the story drift in the frequently earthquake.Inmoderate and rare earthquake, the frame stiffness and carrying capacity decreased largely onaccount of the concentric braces were buckling. By contrast, the buckling restrained brace wasyielding instead of buckling, the frame stiffness decrease slightly and the carrying capacitygoing up steadily. Compared the equal-stiffness principle with the reduced-stiffness principle,the former one can control the story drifts more effectively, and the latter one can give play tothe energy consumption capacity of buckling restrained brace and the compression strength ofcolumn will be decreased more effectively, in the view of economic,the latter replacingprogramme will be better.