Overall Stability Of Cross-Layer Staggered Truss In Railway Station

Among all kinds of large industrial and civil construction already built or under construction, the large span steel structure is one of the most active and widely used types. Compared with reinforced concrete structure, an obvious problem which lies in steel structure is its stability which in many cases limits the bearing capacity of steel structure. On the premise that the individual component shall be in a stable state, the current code shall ensure the overall stability of the structure through structural measures, however, the stability of the whole structure could not be determined quantitatively under this way.As a new structure type, the staggered truss was put forward in the1960s, the relevant theoretical research of staggered truss is still in the development stage in foreign countries and in a initial stage at home. Therefore, very little research about overall stability of steel staggered truss could be found and relevant engineering construction could not be guided through current research results directly.In this paper, numerical simulation and scale test are combined to study comprehensively and systematically the overall stability of cross-layer staggered truss in Daqing station which is the main object. The main research contents and relevant conclusions are as follows:(1) Through data investigation, the principle and classification of the structure stability was expounded systematically in this paper. On this basis, after analyzing external (induced deformation) and internal cause (material nonlinearity, etc.) of the instability of staggered truss, calculation method of nonlinear problems as well as their main controlling factors, the numerical calculation method in this paper was determined.(2)The nonlinear analyzing results of the substructure of staggered truss showed that its overall stability of bearing capacity of has satisfied the code requirement, its buckling mode has presented a half-wave deformation outside the surface, similar to the simply supported plates under the in-plane load and its deformation modes under the action of basic combination of static loading was consistent with the eigen value buckling mode.(3) On the basis of1:10scale, the substructure of staggered truss was simplified gradually to an experimental model based on a simplified principle, the in-plane static bearing capacity and buckling modal of simplified model and original model matched well, which proved that the simplified process was very effective.(4)Numerical calculation and model test were taken on the simplified model, the results showed that out-of-plane displacement of truss was very small when the truss was unstable, in-plane buckling of the inclined web member occurred before the buckling of whole structure. So in actual engineering, it is necessary to pick out possible buckling component of the structure in advance according to the results of numerical simulation to enhance the truss’s stability bearing capacity and avoid its buckling occur before the whole structure is unstable. (5) Based on static initial deformation mode imperfection method, the different sizes of the initial defects within the codes have been introduced to carry out parametric analysis on the scaled simplified model of staggered truss. Analyzing results have showed that the initial defects have a very little impact on the stability bearing capacity of the truss in this paper, thus the truss we study in this paper was not a defects-sensitive structure.