Seismic Strength and Stiffness for Recycled Aggregate Concrete-Filled Steel Tube Frame

Abstract

Tostudytheseismicstrengthandstiffnessforrecycledaggregateconcrete-filledsteeltube(RACFST)frame,two-framespecimens madeupofRACFSTcolumnandreinforcedrecycledaggregateconcrete(RAC)beamwereusedforaseismictestunderreversed low-cycle loading. The failure mechanism, hysteresis curve, strength attenuation, and stiffness degradation were determined for the specimens. The design methods for the story shear bearing capacity and stiffness for the single-layer single-span RACFST framewerediscussed.Itisshownthattheseismicdesignrequirementsincluding“strongcolumnweakbeam”and“strongshear weak bending” can be met. The hysteresis curves are symmetric and the strength attenuation and rigidity degeneration change significantly, then change a little, and then significantly again under the same displacement. It is possible that the methods includingelasticbendingmomentatthecolumnend,plastichingeatthecolumnend,andplastichingeatthecolumnbottomcan all be applied to the design calculation of the story shear bearing capacity for the single-layer single-span RACFSTframe. The method adopted in this paper can be used to estimate the original elastic layer stiffness of the RACFSTframe.