Study And Evaluation On Seismic Performance Of Existing Reinforced Concrete Frame

When concrete structures are built and put to use, its mechanical performance will degrade with increase of serving time and produce durability damage. Now in engineering field, the solution of durability damage in existing concrete structures is based on normal load. There are few researches on damaged structure influenced by earthquake during serving time. This paper is based on study of rebar corrosion which is main factor causing concrete structure durability damage in serving time, load test of corroded hydraulic components of reinforced concrete, building restore reinforce model of serving concrete frame structure and analysis of earthquake response and damage in the structure, and researched on its resistant performance and damage assessment in earthquake.The paper sums up and analyzes influence factor and performance of durability damage for serving concrete structure and mechanical property of material. It defines formula of existing concrete structure material property and unit resistance attenuation model by attenuation function, which also includes link with the Code. Through relative definition and computation, it advances hypothesis of existing concrete structure durability damage assessment by durability damage parameters. It suggests that existing structure need not be adjusted for occasional earthquake during future target usage period, while structure design period is return period of accidental earthquake.17 pieces of reinforced concrete bending corrosion specimens, which are made corroded by way of natural exposure, alternate wetting and drying and rapid electrochemical corrosion, are taken low cyclic loading test in condition of axial compression ratios that studies seismic performance index of hysteric's curve, strength, stiffness, deformation and energy-dissipation influenced by reinforcement corrosion. It also analyzes restoring force of reinforced concrete bending corrosion specimens. It presents that increase of rebar corrosion quantity can change failure characters of concrete structure, and influence stiffness and ductility factor of constructional element. It discusses relationship between stiffness degradation and corrosion damage and influence of structures dynamic computation parameters by above factors. It builds up restore force model of reinforced concrete bending corrosion specimens, which have equal results testified by existing literature test dataThe paper takes earthquake time history analysis of earthquake response for corroded concrete frame and seismic performance evaluation computation based on capacity spectrum method (Pushover Method) of function (rebar corrosion rate)/ displacement. By comparison of concrete frame structure seismic response under different corrosion rates, it presents that when durability damage of existing concrete frame structure takes place, the natural vibration period and vertex displacement are increased accordingly, the seismic response obviously increases and the seismic performance seriously degrades. Especially, when damage increases continuously, frail-layer position may transfer and then increases uncertainty of structure damage and collapse.By comprehensive statistical analysis of existing concrete frame structure parameter index in earthquake collapse, it presents assessment criteria of earthquake damage for existing concrete structure and determines the fixed quantity between assessment criteria and seismic damage degree.The computation testifies earthquake damage assessment model built up by the paper. It suggests that assessment research of earthquake damage in structure be deeper, damage mechanism of structure be simulated, and some unified model of reflecting inner reasons on different grade earthquake damage be built up. The model can give mechanism explanation for structure damage assessment and produce optimal decision about seismic damage assessment of existing concrete structure so that it can be applied in field of reinforcement and earthquake disaster assessment of concrete structure.