Experiment And Design For Middle-Column-Type Cantilever Wall Serving The Viscous Dampers

Cantilever wall is the brace component which is directly connected to damper in energy dissipation structure and it will play a role in transferring damping force to the surrounding main structure. Cantilever usually consists of two parts:upper cantilever and lower cantilever. Damper device fits between the upper cantilever and lower cantilever (usually located at half of story height).The mechanical characteristics and important degree is quite different from the ordinary frame column and shear wall although their shapes are alike to each other. It might say that cantilever wall is not only to be the very important component in energy dissipation structure designing, but also easily ignored at some time. The stiffness and strength of cantilever are the key factors as far as the efficiency of energy dissipation of damper is concerned.It points out that the bearing capacity of cantilever wall is limited to the flexure-shear failure model and concrete wedge splitting which are first generated at loading component. Based on this, two groups of cantilever walls are constructed.The arrangement of steel bars for the first group is ordinary type which can be called traditional type cantilever wall. The second group cantilever walls are equipped with concealed column and concealed beam, and it can be called strengthened type cantilever wall. The experimental results show that the average ultimate bearing capacity of traditional cantilever wall is 584.3kN and flexure-shear failure model and concrete wedge splitting are the main reason for serious cracking and large steel bars strain which directly caused failure. The stiffness and strength of strengthened type cantilever wall are improved and the average ultimate bearing capacity is 749.4kN. Even though, the stiffness and strength of strengthened type cantilever wall can not fully meet the requirement of ((Technical specification for seismic energy dissipation of buildings)) The finite element analysis for two types cantilever wall has been completed by ANSYS and VecTor2 software, it is showed that the crack patterns and strain of steel bars and concrete agree well with the experimental result, but the stiffness of cantilever wall can’t be simulated very well and the numerical result is more "rigid". The ultimate bearing capacity and crack width calculated by VecTor2 are good agreement with the experimental result but only if the bond-slip element to be taken into account. VecTor2 has more advantages than ANSYS in terms of analysis effects.It has summarized the failure characteristics of two types cantilever wall in detail. A modified design scheme of cantilever wall has been presented by using Strut-and-Tie model and Evolutionary Structural Optimization method. It is the core part to move the load component inward 185mm so as to allow plenty of space for concrete strut. The modified cantilever wall has been analyzed by VecTor2 software, and it is showed that the modified cantilever has higher bearing capacity and better mechanical behavior. The crack width can be effectively controlled and the stiffness can also meet the requirement of relevant documentation.