Study On Upper Load Transfer And Foundation Internal Force Of Frame-Core Walls With Large Thick Raft Foundation Under High-Rise Building Complex

The paper studies on the foundation deformation, contact pressure distribution and transfer law of internal force and upper load in the first storey columns and raft foundation by conducting test on two large scale(1:6) models, namely the single frame-core walls structure (Model 1) and the frame- core walls structure with single span and two-storey annex (Model 2). Furthermore, by contrasting these two models, some useful and practical conclusions are drawn as follows:1. When the raft foundation is bending, the longitudinal displacement curves show the basin-shape, and core walls settlement is even. The contact pressure of Mode 1 is of saddle-shape, and the contact pressure gradually transfers from the middle core walls to the side columns and corner posts. The contact pressure of corner columns grows at the fastest speed. The contact pressure of the longitudinal axis of Mode 2 is of basin-shape. The contact pressure gradually transfers from the core walls to the side columns and corner columns of main building and annex. The contact pressure of transverse-side column grows at the fastest speed. Under the normal working condition, the average contact pressure of the annex is 1/2 of that of the core walls.2. The axial force of the core walls is the largest among all the columns. Under the normal working condition, the core walls of Model 1 bears about 2/3 of the upper load, and that of Model 2 bears about 1/2 of the upper load. In the condition of interaction, the structure shows the internal force is re-distributed. The upper load continuously transfers to side columns and corner posts of the main building and annex. The axial force of the transverse-side columns grows fastest of all. The inhibition action of raft foundation vertical deflection of the side column in Model 1, the annex side column and corner column in Model 2 is remarkable. The bending moment of raft foundation under the core walls is the greatest.3. The weak parts of Model 2, including the bottom of longitudinal beams that are connected with the core walls, the rafts under core walls, the floor slab in the inner side of corner posts, the junctional areas between the main building and the annex, and the region of corner posts and side columns in the annex are tend to be broken.4. When the upper load is the same, the settlement value of Model 2 is smaller than that of Model 1, but the deflection value of the main building of Model 2 is larger than that of Model 1. And the contact pressure of the central region in the main building of Model 2 is almost equal to that of Model 1.