The Analysis Of The Seismic Fragility For Reticulated Shells In The Action Of Corrosion

The reticulated shell structure has the graceful spatial formation and the outstanding force ability,which has been widely applied in each kind of architecture.However,its corrosion resistance is poor.With the rapid development of industrialization in China,the environmental pollution is becoming more and more serious and the steel structure is in a long-term corrosion environment.With elongation of the service time,the steel structure would be damaged and failure,making the performance of structure or component degrade and even leading to structural failure and affecting the structure seismic performance,such as the corrosion.Seismic vulnerability analysis is the main method and means of structures seismic evaluation,and also the main development direction of current seismic risk analysis.Domestic and foreign scholars have achieved fruitful results on the steel corrosion mechanism and seismic vulnerability.However,most studies on the corrosion function of steel structures are still at the stage of material properties,and there is no research on the seismic behavior of reticulated shell structure under the corrosion action and and accurate evaluation of the overall life-cycle reticulated shell structure for practical engineering applications can not achieved.Under this background,this paper studies seismic vulnerability assessment of single-layer reticulated shell structure by considering the corrosion through the combination of steel mechanical properties degradation mechanism and seismic vulnerability analysis principles under the corrosion action.And the main contents of this paper are as follows:Firstly,this paper introduces the research methods of atmospheric corrosion tests of metals,discusses steel corrosion mechanism and its influencing factors and further deduces the constitutive relation under atmospheric corrosion through the influences of atmospheric corrosion on the durability of steel and the degeneration law of steel mechanical property,according to the previous research results on atmospheric corrosion of metals.Then,the paper introduces the basic theories and research methods of vulnerability analysis and conducts the vulnerability analysis of reticulated shell model respectively by comparing the influences of different roof loads and ratio of rise to span on structure seismic behavior and adopting vulnerability research method of dynamic time history analysis and using finite element software to establish the damage model of reticulated shell structure.The results show that the reticulated shell structure has good mechanical properties and can keep strongstability under large seismic intensity;the ratio of rise to span has great influence on the vulnerability of reticulated shell structure,and the structure with smaller ratio of rise to span tends to be more stable and have lower probability of structure failure;the effect of roof load on structural seismic vulnerability is higher than that of ratio of rise to span,and the roof load with large structure is more likely to be destroyed at the same seismic intensity.At last,the steel constitutive relationship by considering corrosion is introduced into the analysis model of seismic vulnerability and three structural models with different corrosion ages are established.The structure seismic vulnerability analysis shows that when the seismic peak acceleration was 2.6 g the structural which under the action of corrosion with 0,15,and30 years,exceeding probability with minor damage is 73.6%,78.1% and 85.3% respectively,which indicates that the degradation of structural stiffness will speed up and the failure probability will increase with the development of the corrosion of the structure year by year.