Study On Design Method For Single Foundation Under Column With Water-Proof Floor

The combination of single foundation and water-proof floor are more and more used for the multi-frame structure and the podium of high-rise buildings podium. But there are always some problems, such as cracking and arching. Aiming at a new practical basement structure composed of single foundation with water-proof floor, the numerical simulation analysis are worked out as the followings:(1)Four current design calculation methods are summarized. For a case, the use of four kinds of methods were calculated, and given the results of the analysis and reflection. The result shows that the simplified segmentation calculation method may bring certain risks with independent calculation on single foundation and water-proof floor. The result of the simplified integral method is more close to the calculation of the software. Four calculation methods have failed to account for the problem of uneven distribution of reaction(2)Aiming at the defects of the four design methods, the ANSYS software is used for contact nonlinear finite element analysis on this paper. Mainly four aspects are studied from the foundation settlement, the foundation stress of top and bottom, the contact reaction force and the diffusion of soil mass, three axial compression ratio were used for comparative analysis. There are following conclution: one of the main reasons for the waterproof floor is the increase of the axial compression ratio, the increment speed of the waterproof floor settlement is slower than that of the independent foundation settlement. foundation deformation is based on waveform, and the whole settlement figure is distributed as a basin;The top of water-proof floor is in tension, and its value increases with the increase of axial compression ratio, the largest tensile stress was appeared in the water-proof floor between the independent foundation plate, cracks occur due to the parts of the tensile stress value is greater than concrete tensile strength design values; The stress generated by the contact element can reflect the counterforce size of soil, the contour of contact force is spread from the independent foundation to water-proof floor center, in the case of axial compression ratio,the increase of the independent reaction force is larger, and the water proof plate has no obvious change, therefore, the increase of the upper load has little effect on the contact force of the water-proof floor. The contact reaction of the independent foundation is about five times of that of the waterproof board, and the distribution of the contact reaction force has certain regularity.(3)Finally, on the basis of ANSYS contact analysis, the relevant data of the finite element analysis results are extracted, and the problem of uneven distribution of reaction is studied. The contact force is plotted to make the section diagram and the 3D surface map, andthe nonlinear curve fitting is carried out. Then, Some parameters in the general formula are given in the table.