The Design And Pattern Selection Study Of Box Foundation And Mat Foundation

The design for trunk formed base and raft formed base is presently realized by computer software by all designing institutes. It is applicable that those designs require the biggish base and increased quantity of reinforcing steel bar to improve the safety performance of the buildings.But following those designs are the ample margins to section measurements and reinforcing steel bars so that caused great economic waste. Besides, the form selection of trunk base is only estimation. With the quick development of high buildings, it is necessary for the architectures to get the scientific conclusion with fix quantity and quality in internal power analysis and designs for trunk formed and raft formed bases. Different analysis of internal power and theory will lead to the specific treatment in designing the buildings and different methods adopted will result in ample diversities in basic investment and securities. It is required by the present status of construction industry that we should proceed to standardize the analysis and conclusion to trunk formed and raft formed bases on the basis of presently acquired theoretical data so as to realize instructive analysis with fix quantity and quality in designing the trunk formed or raft formed bases. This article makes separate designs with trunk form and raft form by the same conditions and proceed with practical discussion to the selection of trunk formed or raft formed bases by analysis.The main contents of this article include:1,This article makes the design of the base of 12 floors building by framestructure. The building base adopted trunk formed base and raft formed base separately and took into account the internal power in trunk formed base about space power conditions by finite element method. The calculation is made by both hand and the computer, and then makes comparisons between these two methods.2,About the calculation of the internal power on raft formed base, we first analyze the upper structure with the use of agglomerate technology on its sub-structure, and make an analysis on raft formed base of Winkler groundsill by finite element and boundary element. Then an integrated coupling formula will be established by the balance of the power and the coordinating of the displacement. And then compared the acquired internal power with the one got by computer software PKPM.3,This article provides some suggestions for the design of trunk formed base and raft formed base, and makes the comparison of the two projects by both technology and economy consideration, and discusses on the choices of trunk formed base and raft formed base.The calculating results of the design show the following three points:1,About the study on the calculating of the internal power in trunk formed base about space power conditions by finite element method, the results are not significantly different compared with the result acquired from hand calculating. However, it is much economic to calculate by hand for the lower part of the 12 floors building structure.2,To consider the raft formed base of Winkler elastic groundsill under the joint efforts of upper part, with the coupling method of finite element and boundary element.3,The differences of the calculating methods between the trunk formed base design and raft formed base design, will result in the big difference on basic investment.To sum up, while comparing calculating the internal power in trunk formed base about space power conditions by finite element method and hand calculating method, we know that it is more economic and suitable to calculate by hand; while comparing considering the raft formed base of Winkler elastic groundsill under the joint efforts of upper part by coupling method of finite element and boundary element and some other common methods, we know that it is more accurate and can be a reference to the project.