Evaluation Of The Reinforcementpiate Size On Flange-plate-reinforced Connction

The conventional steel frame beam-column joints had a lot of brittle failure,which wasin the Northridge earthquake in United States at 1994 and Hanshin Awaji earthquake inJapan at 1995. After the earthquake,National experts have had a large number ofexperimental studies and theoretical analysis, and proposed a variety of new ductile joints, including reduced ductility joints and reinforced ductility joints. In this paper, theflange-plate reinforced joints is reinforced ductility joints.The works of flange-platereinforced joints is: through welding a reinforced plate at the beam-end to improve themoment of the beam-end section, the plastic hinge has been taken away from thecolumn-flange weld which is brittle and suffered complex stress to achieve the purpose ofimproving the ductility of joint to prevent brittle fracture.According to the FEMA-350 and the relative standards of design and constructionrequirements,four Steel frame flange-plate reinforced joints were designed at 1/2 reducedscale in this paper,and flange-plate reinforced joints were experimental studied undercyclic loading, the influence for seismic performance form he strengthen and thickness ofreinforce-plate were ansysed. Experimental phenomena that he plastic hinges of the fourreinforced joints specimens all formed at the position where away from the end ofreinforced plate about 1/3 beam depth,which is awy from the column flange,beam-column joints to connect the protection of the weld, are ductile failure.The Data Analysis show that:1) 4 specimens showed good seismic performance. Fullhysteresis curve, the hysteresis area is relatively large, Plastic rotation of joints greaterthan 3% rad, the total angle is greater than 5% rad, ductility factor greater than 3.0, whichachieved good seismic performance of steel frame bending the minimum standards.2)When the length of reinforce-plate within a reasonable size, with the length ofreinforce-plate increases, the ultimate bearing capacity of specimen will be significantlyincreased, but decreased ductility and energy dissipation. 3)the length of reinforce-plate isshorter, the ultimate bearing capacity is lower, the capacity of energy dissipation is higher,but the short length, the relocation of the plastic hinge can not effectively, thereforeproposed to strengthen the board length range (0.5 to 0.8) times as high beam.4) When the thickness of reinforce-plate within a reasonable size, with the thickness ofreinforce-plate increases, the ultimate bearing capacity of no significant change, butdecreased ductility and energy dissipation. 5) With the thickness of reinforce-plateincreases, the ultimate bearing capacity of no significant change, so the thickness ofreinforce-plate should not be too large. Therefore proposed to strengthen the range ofthickness values (1.0 to 1.3) times the beam flange thickness.