Abstract:Steel Structure is widely used for industrial architecture because of its advantages of being light weight, higher strength, and better plasticity and toughness. Unfortunately, the poor performance that resists corrosion has been gradually found recently with the steel widely used. The seismic performance of structures in different service times is necessary to be evaluated since the corrosion of steel directly lead to the deterioration of seismic performance and stiffness of structure. In order to study the impact of corrosion on steel mechanical properties in the acidic atmospheric environment and then analysis the seismic vulnerability of multi-age steel structures, 105 standard steel material specimens corroded by artificial climate accelerated corrosion test technique were carried out under tensile test. Based on tensile test data, the linear regression relationship between the steel mechanical properties (yield strength, ultimate strength, elongation, elastic modulus) and weightlessness rate was established. At the same time, the corrosion rate and the initial corrosion time of steel bent frame structure were accounted for by using findings from related research. Based on the result of material performance of different corrosive steel in acidic atmospheric environment and combined with corrosion rate and the initial corrosion time, the analysis platform SAP2000 was employed to build numerical models of steel bent frame structures with different service times (30 years, 40 years, 50 years, 60 years).In order to eliminate the influence of uncertainty of seismic record, 24 seismic records had been chosen in this paper. The incremental dynamic analysis (IDA) was carried out on the models with PGA as the earthquake intensity index and maximum inter-story drift as the seismic demand index. The relationship of probabilistic seismic demand was obtained by IDA analysis for multi-age steel bent frame structures. The statistical parameters of the probabilistic seismic capacity model were evaluated using existing research. Consequently, seismic vulnerability curves of multi-age steel bent frame structures were established in accordance with seismic demand model and seismic capacity model. Furtherly, earthquake damage matrixes were obtained by seismic vulnerability curves. The results of this research provide support for seismic risk assessment of multi-age structures.
