The Seismic Response And Elastic-plastic Analysis Of Concrete Frame Structure With Light Steel Add Layer

Light steel adding layers technology is more and more widely applied in the practice of additional stores and renovation of existing buildings. Light weight, short construction period and low cost advantages are the general advantages admitted by engineers and technicians. At present, the study of light steel adding layers is mainly focused on the elastic seismic response of adding layers structure and the local structural measures, etc., in order to study adding light steel layers much deeply after the vibration characteristics of structure system, this paper made the following research works.First, this paper respectively analyzes the factors which influence the overall performance, like the damping ratio, stiffness ratio and the number of adding layers. Comparing the modal damping ratio, the equivalent damping ratio, and the experience of equivalent damping ratio, results showed that using the modal damping ratio can be more accurate to consider the damping characteristics of light steel coating composite structures and can better reflect the influence of high-order vibration mode. According to the experience of damping ratio larger error can be caused.Secondly, for a frame structure of adding one to three layers of light steel structure, the first12order vibration mode damping ratio of structures is calculated respectively. The custom response spectrum corresponding to the first12order cycle is formed through the study of the damping coefficient of standard response spectrum with corrected the earthquake influence coefficient values, compare the seismic response values from the custom response spectrum with values from response spectrum when damping ratio is0.04and0.05. It is find that if found not fully consider the influence of damping adjustment will cause larger calculation error, and the error increases with increased the number of layers.Again, through the different number of layers of light steel and overall structure for static and nonlinear elastic-plastic time history analysis, it is find that with the layers of the increase in the number, weak layer moved up significantly. For the middle floors above and below the layer of floor, deformation trend will produce the opposite effect.Finally, in view of the light steel after adding layers tending to lead to the bottom of the vertical bearing capacity of the column in shortage and doing the outside steel reinforcement, the static and dynamic elastic-plastic analysis is analyzed in the program of SAP2000with outside of the light steel and reinforcing steel frame structure. It is find that at the bottom of the extension-story reinforcement have larger influence on local seismic performance.The ductility of whole structure is not obviously improved in the practice.In conclusion, this paper studies the specific light steel coating has the very good guiding significance of engineering practice, can be used for reference in the similar engineering design.