The Research On Correlative Problems About Transfer-floor When Upper Border Columns Are Out-shift

The structural forms are usually changing between upper floors and lower floors in modern tall-buildings. So it's necessary to construct transfer-floor. At present times, there are many researches focusing on the transfer-structure where upper border columns' axis contract or coincide with lower floor, while few on the transfer-structure where the upper border columns' axis is out-shift. When the upper border columns' axis is out-shift, it's different from common transformation, refers to the transfer-floor cantilevering. Therefore, when designing the transfer-floor, we should know its transferring way of force, carrying capacity and relevant transformation. In addition, for the transfer-floor cantilevering, there is large tension in beams and slab. The large tension may make them crack. So test research and theoretic analysis should be done to optimize designing such type transfer-structure. The dissertation comes from an actual project. A model test study for transfer structure with corbel was carried out. By studying its mechanical behavior, deformability and crack developing of members of transfer-structure with corbel, mechanical characteristic and mechanism of the structure were discussed. Then combining with nonlinear finite element analysis result, analysis method was verified and relational design suggestions were presented. This research was conducted as follows:1. Combined with an actual project, a static loading model test for transfer structure with corbel was carried out. The model is made in a scale of one fourth;2. According to the test result and crack developing, the paper analyzed the specimen's mechanical and deforming performance in the whole course of loading and found out the way by which force transferring and each member mechanical status;3. Nonlinear finite element analysis for the test model was carried out by using finite element program. Then the analysis' results were compared with the test's results.4. Referring to codes, the related design problems of such type transfer-structure was discussed and some design suggestions were presented.The dissertation's research indicates that the large transfer-corbel's rigidity is so good as to be approximately as a rigid body when calculating internal forces of transfer-structure. Current code for design of concrete structure (GB50010—2002) is relatively safe in setting down the corbel's height, horizontal longitudinal reinforcing steel bar and stirrup. The beam, which is connected with corbel, is a eccentricity tensile member. The beam needs being prestressed, in order to control the corbel's sidesway and to hinder beams and slab from cracking, by which the structure can be guaranteed working in order. On condition that the beam can satisfy to bear load-on-floor not to deform largely and meet structure detailing requirement, the beam's section size should be designed to be small as far as possible. So structure's height can be reduced and usable space of this layer increase. It is also helpful to meet anti-seismic requirement that the shear-rigidity ratio of upper floor to lower floor less than two.Mechanical and deformation performance of such transfer-structure are relative to many factors. So it's necessary to perform more study.