Integral Design And Seismic Resistant Property Analysis Of The Adding Steel Stories On The Top Of The Original Buildings

Most of the urban residential and other civil buildings built before 1980s were low-rise or multi-storey. It is not economic of pushing down those buildings but expanding area is the urgent need; even some of these buildings are not earthquake-resistant qualified or don't satisfy the seismic fortification criteria. Under this circumstance, the technique of adding stories can be employed to strengthen and modify these buildings for ameliorating its usage, seismic reinforcing and improving the dissipative system.The technique of adding stories with steel structures is gradually promoted to be a new type of structural reinforcement for its advantages of light weight, good earthquake-resistant performance and easy construction. Also, it is superior to concrete structure in aspects on technology, economy and safety; therefore this technique is widely used in China. However, the design method is not mature yet; mostly, only the load bearing capacity of adding part is considered. But, significant differences of the whole mass, stiffness, period and damping occur when adding steel structure on the original building. Therefore, it is no longer suitable of just calculating the adding part, and the analysis of the entire structure ought to be carried out. Based on the practical projects, this thesis conducts parametric analysis and summarizes the regulations by finite element software, directly aiming to the characteristics of the technique of the adding steel stories on the concrete frames and brick mansions. The main objectives include the followings:(1) Design and pertinent techniques of the steel adding stories systems: According to the different properties of the original structures and the different functions of the adding stories, the optimistic structural scheme of adding stories is proposed. Further investigations focus on the design of the infirm parts of the system based on the chosen structural scheme, as well as the reinforcement of the original structures and the joint design between the steel adding parts and the original structures.