| After the WenChuan Earthquake the government improved the earthquake fortification level for primary and secondary school, and therefore most of the primary and secondary school buildings all over the country need seismic retrofitting. Buckling Restrained Brace is a special center support which consist of the central brace and the metal-yield dampers. It can be applied to steel structures, reinforced concrete structure as well as reinforced concrete frame structure for both newly-built building or retrofitted one. Compared with common brace, Buckling Restrained Brace have more full hysteretic curve, and it will yield under both tension and compression, and the installation process is easy to operate. The use of BRB in seismic retrofitting can greatly shorten the construction period, diminish the amount of work and reduce costs. During an earthquake Buckling Restrained Braces provide lateral stiffness in the elastic stage, and consume energy as first line of defense in the elastic-plastic stage to effectively reduce the structural component damage and protect the main structure, then the overall seismic performance can be improved.In this paper, the detection, identification and seismic strengthening design for a teaching building in the No.l high school of Yuxi was discussed. The performance of the building after retrofitting was also discussed. An elastic-plastic analysis has been conducted to this project to ensure the building meet regulatory requirements. Studies are as follows:1. describes the background, origin, purpose of the research, and summary the detection, identification and retrofitting used in practice nowadays, and describes an overview of the buckling restrained braces.2. Testing and evaluation was applied to a teaching building in the No.1high school of Yuxi. The items include:(1) the use of detection intensity rebound method to calculate the reinforced concrete strength.(2) the detection of section size of components.(3) detection of seismic structural measures.(4) evaluation of the test results.3. The qualification was conducted to the school building according to test results. The items include:(1) identification of safety and use proper, PKPM modeling, and seismic bearing capacity checking.(2) identification of first level seismic measures, include:structural system, materials, the actual strength, the configuration of vertical reinforcement and transverse stirrup of components, reliability of component connections, identification the connection between infilled wall and structure, etc.(3) Using PKPM software to check second level seismic capacity of components. Finally, conclusions of seismic qualification was concluded.4. Seismic strengthening design of school building. Unloading method, increasing section method, outsourced steel method, carbon fiber strengthen method, additional shear wall method, energy dissipation method, isolation method were discussed. Bearing capacity, displacement and deformation of the building after retrofitting ware checked.5. Elastic-plastic analysis has been conducted to reinforced shool. Seismic performance analysis method was described. The seismic performance analysis for the reinforced school included:(1) In the case of rare earthquake, using push-over method conduct elastic-plastic analysis for the reinforced school.(2) In rare earthquake situation, the dynamic elastic-plastic analysis method was conducted for the reinforced school.(3) Analysis the seismic performance required to achieve targets.6. Make a comparison for the structure before and after reinforcement. Include:(1) Dynamic characteristics test comparing before and after reinforcement.(2) PKPM was adopted to make calculation analysis for the model before and after reinforcement to have a comparison of key control indicators.(3)the dynamic elastic-plastic analysis method was conducted to compare to the seismic performance before and after reinforcement. |
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