Research On The Application Of Dissipating-energy Brace In Seismic Strengthening Of The Masonry Structure With Bottom Frame Beyond Code Limit

Under the historical background of the economy’s rapid development and the overall design level’s slow improvement,Masonry building with concrete frame structure on ground stories as a social product rises.It soon comes into widely use because of its feautures of large space in the base and its low costs in the contruction.But the seismic performance of masonry structure with bottom frame has intrinsic shortcomings,in order to make up for its intrinsic shortcomings,The current code of China has put forward strict restrictions on the number of storey,height and structural arrangement.However,since the 1990 s,As the China’s urbanization process continued to accelerate and a large number of rural population began to pour into the town,frontage buildings have a growing demand for the lower floors of shops and upper houses,Becacuse of this demand,there has been a large number of masonry buildings whose number of the bottom frame layer and the upper masonry layer or the total height of the building exceeds the standard requirements.All of these make the characteristics what " upper’s stiffness is stronger than bottom " more obvious,increase the complexity of seismic and also have a lot of security risks.Therefore,according to the strong earthquake elastic-plastic time history analysis,it is very necessary for engineers to put forward the anti-seismic reinforcement scheme for masonry frame structure beyond code limits.At present,,apart from the commonly used methods for seismic strengthening of buildings,such as increase the load-bearing member section,steel,the addition of seismic walls or steel support,etc,using energy dissipation technology to reinforce structure has become a new seismic design method.Now the research of seismic isolation and shock absorption technology in domestic scientific research units mainly focuses on the development of isolation bearings and dampers and their mechanical properties,calculation models and dynamic analysis methods,and the research on the application of the energy dissipation device in some special projects and the setting of the product parameters is relatively small.Based on the study of a large number of documents at home and abroad,this paper takes the masonry frame structure beyond code limits in the east of Sichuan Province as the research object and can be summarized as follows:1、According to the investigation,the actual structure of the research object has been grasped.Pulsating method is used for the structural dynamic characteristics test to obtain the natural frequencies,mode shapes and damping ratio,then we use the parameters to correct or verify the theoretical model and explore the design characteristics of this kind of structure by finiting element analysis method.Modal analysis and elastic-plastic time history analysis show that: the structure’s lateral stiffness has mutation,and the horizontal displacement of weak layer in the bottom frame is more obvious than that of the upper floor.Due to the original structure adopted some seismic walls and other seismic measures,longitudinal maximum lateral position is on the second floor bottom frame,horizontal maximum lateral occurred in the transition layer.The whole building under earthquake deformation and masonry structure and frame structure,shear deformation is obvious.The overall deformation of the building under the earthquake is consistent with the masonry structure and the frame structure,which is a style of shear deformation.2、 In this paper,I have done a lot of research,such as the analytical method of installing a damper to reinforce a house,and the selection and arrangement form of the dampers.Research results show that: under the basis of the dynamic characteristics of structure to select the type and arrangement form of the damper can obtain a good damping effect in the case of energy dissipation components as little as possible.3、Based on SAP2000 finite element software,the elastic-plastic time history analysis is carried out to calculate the seismic response of energy dissipation system,at the same time,it also offer some indicators such as the peak acceleration、story drift、interlaminar shear 、the shear force of the bottom frame and so on.Based on compare of original structure analysis,the results show that adding damping energy consumption at the framework layer support can significantly reduce the seismic response of structure,and make the main stress components not damaged under small earthquakes by dissipating most of the energy in structural elastic stage.4、By comparing the difference between the traditional seismic wall and dissipating energy technology in structural reinforcement from effect 、 cost、operability and space construction,Some suggestions are given on how to select suitable structural reinforcement schemes in this house to resist the earthquake response.