Reserch On Seismic Performance Of Over Lengthened Buckling-restrained Brace In Segment Weld

In China, Most of the framed bent industrial buildings is located in high intensity seismic region and only have one seismic fortification line. Adopt buckling-restrained brace(BRB) is an efficient and reliable method for energy dissipation and vibration attenuation. This paper mainly discusses the over lengthened buckling-restricted brace in segment weld(L-BRB) structure and seismic behavior, which can be used in the framed bent industrial buildings.Buckling-strained brace(BRB) is a new type of energy dissipation, yield under tension and compression state, eliminates the traditional steel support compression buckling problem, have stronger and more stable energy dissipation capacity under strong earthquake, so as to protect the main structure. For some lifeline engineering, such as large industrial workshop, large industrial workshop, air cooling island, large hangar and railway station, structures span of 20 meters, overhead can be up to 30~50 meters or more, and the civil construction has bigger difference in civil architecture.These special structures needed to support the length of up to 30~50 meters. At present, BRB length size range mainly concentrated in 3~10 meters, usually in the slenderness ratio of 25 within, difficult to apply in these structure.Mainly L-BRB weight is bigger, the initial deflection is big, it is difficult to meet the specification requirements, seriously affect the support work behavior.According to the above problem, based on the engineering background of air cooling island structure, puts forward a new type over lengthened buckling-restricted brace in segment weld(L-BRB).The new L-BRB core units and constraints can be segmented independent production and construction site splice assembly.Through finite element analysis and experimental study on seismic performance of L-BEB.By using ABAQUS software to L-BRB simulation analysis, study a variety of factors affect the performance of support and hysteretic energy dissipation performance and get design parameters of the limit.Then in order to study L-BRB regularity of rigidity degeneration, hysteretic behavior and energy consumption property low cyclic loading test was performed on a ratio of 1:8 long scale,two period of connection of L-BRB.A study of the causes of the experimental phenomenon, regularity, the structure and make improvement measures are put forward. At the end of the original structure and the addition of L-BRBs air cooling island structure are analyzed with the performance.Research shows: the new L-BRB by subsection manufacture and field assembly,weight is small, can effectively reduce the initial deflection, can be successful make a medium scale and long scale(15 to 50 meters) L-BRBs.The finite element analysis shows that L-BRB stability of the support design control parameters limit should be higher than the general BRB, restraint coefficient and steel core width-to-thickness ratio is the main factor that influenced the stability of the L-BRB working performance. By analysing hysteretic curve obtained by the test, have a certain energy dissipation ability, compared with the general BRB P-? effect is obvious. Analysis of the test specimen of steel core in high order buckling instability, hysteretic curve is not full, severe fluctuations under pressure, the cause of these serious problems is clearance is too large. Then the structure and process improvement Suggestions are put forward. Successful experience is gained by the experiment, the L-BRB production convenient, small weight, vertical deformation control, coordinate work between components, the overall stability can be guaranteed, specimen processing should strictly control the clearance between steel core and constraints. Structure analysis comparison results show that after joining the L-BRBs structure construction torsion be suppressed, reduce the structural response under the action of earthquake,the structural seismic performance significantly increased.