A Study On Seismic Retrofit Method Of Teaching Building And Joint Gallery With Single Bay Frame In Primary And Secondary School

The May12Wenchuan earthquake has witnessed severe damages to teachingbuildings with single-span frame structure, which has aroused wide concern amongscientific researchers as well as engineer designers. Accordingly, the national SeismicDesign Code and relevant regulations have been updated, specifically stipulating thatsingle-span frame structure be banned in Category II structure. However, there remainsa large number of existent single-span frame structures in urgent need of seismic retrofit.Thus, it poses one of the engineering conundrums to carry out the seismic strengtheningof those structures in a reasonable and effective way. The thesis explores a scheme ofseismic retrofit in terms of the addition of reinforced concrete shear wall applicable tothose structures, seeking to provide an easily implemented retrofit design focusing onthe overall anti-seismic performance.This thesis proposes three different retrofit schemes respectively for threesingle-span reinforced concrete frame structures of teaching buildings, namely, onedesigned for degree6earthquake (0.05g), another for degree8earthquake (0.2g), bothconstructed under GBJ11-89Specifications, the third for degree7earthquake (0.15g) inan actual single-span joint gallery frame structure. With OpenSees software, acorresponding model for structural analysis is established. Within a certain scope ofearth tremors, the study analyzes seismic responses to different input levels of frequentearthquake, design earthquake and rare earthquake. Meanwhile, it investigates laws ofvariation of internal forces and reinforcement of the original framework, caused by theadding of the shear wall. Based on the findings, the author proposes a scheme of seismicretrofit for single-span teaching building as well as the single-span joint gallery framestructure.This study finds out that laws of installing shear wall in retrofit vary according todifferent seismic intensities: the anti-seismic performance meets the regulatoryrequirements if the seismic overturning moment assumed by the shear wall in asingle-span structure designed for degree6earthquake reaches over50%of the totalseismic overturning moment. As for the single-span building designed for degree8earthquake, apart from meeting the requirements of seismic overturning moment, itmust conform to the story drift angle limitation, the latter taking a controlling role. Theaddition of shear wall, while improving the overall seismic performance of structures, boost the need of reinforcement of certain existing components especially in structuresfor degree8earthquake which, with the increase of the length of the wall limb, needsreinforcement due to insufficient load bearing capacity of existent components.As for the multi-layer single-span frame joint gallery designed for degree7earthquake, influenced by the arrangement and number of its shear walls, overalldeformation of inter-layer structure increases as a result of a small increase in the lengthof coupled shear walls. It is reasonable and effective to reinforce according to theshortest length needed for changing the frame structure and form. Consequently, thereinforcement in the beams of the original frame structure is least affected by thereinforcement.