Research Of Eccentrically Braced Frames With Replaceable Link Beams

Eccentrically braced frames (EBFs) have an adequate stiffness, as well as a goodductility and an excellent ability of energy dissipation, but it’s difficult to restore afterearthquake. A new EBF system with replaceable link beams was proposed, which change theordinary link beams with some dampers that have good shear performance. We can replacedampers or use some dampers with good recovering performance to restore after earthquake.The main contents of this paper are showed as below:(1) A brief introduction of new EBF system was given, dampers with good shearperformance that were used on replaceable link beams include steel shear panel damper(SSPD), lead viscoelastic damper (LVED) and lead-filled steel tube damper (LFST). Theirdesign details, construction forms and energy dissipation principle were given respectively.(2) The finite element software ETABS was used to analyse EBF system with ordinary Hsteel panel, SSPD, LVED and LFST during elastic phase. Energy dissipated structures canreduce seismic responses and internal forces of beams, columns, braces significantly. SSPDsupply stiffness under frequent earthquake, but LVED and LFST both start to dissipate energyand their responses are obvious relatively. While SSPD start to make effects under fortifiedearthquake, which performs a good result as well as EBF system with LFST on link beams.(3) The finite element software PERFORM-3D was used to analyse EBF system withordinary H steel panel, SSPD, LVED and LFST during plastic phase. Each damper used theirprinciple to absorb energy significantly. The energy hysteresis curves of dampers aresymmetrical, full and stable, they all have good hysteresis performance and well energydissipated ability. Through performance estimate of structural members, we can know thatthey all achieve “strong columns and weak-relatively beams” principle, and energy dissipatedstructures can reduce structural members that get into buckling phase. In general, structure with LFST performed the best effect.(4) The design details of LFST were introduced. Different parameters that affectstructural performance were analysed, which include different height-width ratio of steel tube,different weaken central thickness ratio of steel tube, different extrusion ratio of steel head.The results show that when height-width ratio varies from1.67to2.67, central tube thicknessratio varies from0.4to0.8, extrusion ratio of steel head varies from0.53to0.8, LFST canperform good energy dissipated effect.