Steel Frame-Reinforced Concrete Hybrid Structure Seismic Performance Of Work

In the hybrid structure whose roof structure with steel and the lower structure with reinforced concrete, there is a design mainstream for building its upper envelope with steel frame. However, it is still analyzed separately about the integral analysis of the lower and the upper structure in the anti-seismic analysis of that hybrid structure. It has not reached integrate so far because that the study about the collaborative work of the lower and the upper structure from that hybrid structure is in its infancy.This paper takes the Ningxia Natural Science Foundation (NZ12164) as the basis and does the nonlinear finite element analysis combining with the example of Ningdong Stadium Project-a hybrid structure of steel frame and reinforced concrete. The comparative analysis between the integrate structure analysis with different damping ratio and the different design methods analysis of the stadium is considered.The methods I have used and the conclusions I have drawn include:The main theory for hybrid structural dynamic response analysis of different materials than the theoretical damping, Midas Gen software provides a hybrid structure structural damping ratio each input function. After studying the damping ratio of hybrid structure, the influence of the crucial factor-damping ratio is considered, then conducting the comparative analysis between two different damping ratios. One is the two different materials’own damping ratio, the other one is two comprehensive damping ratios. In that comparative analysis, including the seismic response factor, the displacement by interlayer and angle of reinforced concrete, the internal forces ant the displacements. Studies have shown that:The calculation results from the different damping ratios of the hybrid structure reach to the standard requests, and the first three vibration modes are the translational at X and Y direction, the torsion at Z direction. The damping ratio of the hybrid structure of the low order vibration mode is close to 0.05 whether the high vibration’s damping ratio is close to 0.02. Found using various structural damping ratio can be a true reflection of the overall structure of the earthquake, also can provide a comprehensive reference damping ratio; Under earthquakes, the larger damping ratio of structural results in the smaller displacement between the integrate structure. Different damping ratios don’t influence the internal forces and displacements of the truss elements and the beam elements obviously, and they keep the same. It is best to use each structure’s own damping ratio when designing such a hybrid structure. If can’t, the recommended value will be 0.04.In this paper, the establishment of the hybrid structure by rigid and articulated two overall model, the parameter is identical with the actual project, carried out with the existing design methods used separately design comparative analysis, comparing static capacity, dynamic characteristics, the seismic response under the small earthquakes and the strong earthquakes. Studies show:Under static force, the integrate analysis makes the more uniform displacement of steel roof, the smaller mutational differences. After analyzing the dynamic characteristics, we can see the saltation phenomenon happens when analyzing separately. While the overall analysis doesn’t appear and is more closer to the actual structure of the analysis of the frequency change; the upper part of the steel structure of the stiffness of the overall structure of the vibration characteristics relatively large, need to consider the synergistic effect of the lower structure when designing; small earthquakes, earthquake overall analysis is magnified, making the structure part of displacements and internal forces are magnified; the seismic response of the hinged connection is stronger than the rigid connection; During destructive earthquakes, the seismic displacement response of integrate analysis is greater than it of separate analysis. Besides, the integrate analysis is important for the vibration isolation. using a separate calculation will result in a waste of materials, not up to economic requirements; the seismic response of the rigid connection is a little stronger than the hinged connection; overall analysis of the resulting number of plastic hinges and plastic hinge analysis alone significantly higher grade steel roof, indicating poor overall analysis ductility in the design should be strengthened.The main innovation of this paper consists of the following three points:(1) Establishing a steel frame-Reinforced Concrete mixing overall analysis model structure, considering the seismic response caused by the damping ratio to the overall structure, and analyzing comparatively on the following aspects:seismic response coefficient, layer displacement and displacement angle of reinforced concrete structure, the internal force and displacement of the truss.(2) Conducting the integrate finite element analysis of hybrid structure Stadium in Ningxia, establishing rigid connection mode and hinge connection mode between the top and the bottom of the structure after that, analyzing comparatively with the plastic hinge under static load, small earthquake and strong earthquake.(3) Conducting the integrate structure analysis of hybrid structure of Ningxia Stadium under strong earthquakes, revealing its failure mechanism, finding the destruction mode in the whole structure, and proposing the strengthening measures.