Design And Analysis Of Frame Structure Based On Uneven Settlement Of Foundation

With the progress of times, widely use of diversified building and complex diversity of geology, demands of security and reliability in structure design are greater. Only structure design achieves security and stability requirements,buildings can reduce potential risk to a greater extent.In addition, construction accidents caused by uneven settlement of foundation occur from time to time. In order to better understand the influence of uneven settlement of foundation on upper frame structure, and reduce the occurrence and danger of accident about frame structure, it is very necessary to make further research on frame structure with uneven settlement of foundation, and providing great reference value for practical frame structure design and reinforcement.This paper using finite element software ANSYS to set up structure model including foundation, basis, beams, slabs and columns, simulating and analysing the influence of uneven settlement of foundation on upper frame structure; Then, carrying out monolayer space frame structure test, observing and recording the deformation and crack development regularity of specimen in the process of uneven settlement; Finally, combining ANSYS calculation results and laboratory test results, and summing up the influence of uneven settlement of foundation on stress, strain and cracksupper in upper frame structure. In the experimental process, when the differential settlement was 0.004L(L is adjacent intercolumnation), frame beams appeared the micro-cracks. In the simulation operation of ANSYS, when the differential settlement was 0.00357L(L is adjacent intercolumnation),frame beams appeared the micro-cracks. The experiment verified code for design of building foundation(GB50007-2011). The allowable subsoil deformation in lower or medium compressible soil is 0.002 L and in high-compressible-foundation-soil is 0.003 L, that regulations has great security. Under the same conditions, the influence of uneven settlement of mid-span foundation on the upper frame component is larger than that of the side-span.ANSYS simulation was used to analyze the rules of uneven settlement amount in upper frame structure influenced by foundation stiffness, basement stiffness, foundation types and underground caverns: The size of the difference of the stiffness of the uneven foundation affects the uneven settlement of the frame structure, but the influence degree is smaller thanthe influence of the foundation stiffness on the frame structure; In the same condition, the bearing capacity and the stability of strip foundation was often stronger than the independent foundation; The different foundation stiffness, the influence degree of the uneven settlement of the frame structure is different; The foundation stiffness is related to the modulus E and the moment of inertia I, and the greater the foundation stiffness, the greater the uneven settlement of the upper frame structure; The influence of the uneven settlement on upper frame structure was different with the different location of caves; In inhomogeneous geology, the larger the transverse section area of cavern at the bottom of the beam near the crossroads of strip foundation, the greater the influence of the uneven settlement on upper frame structure; If cavern was existed at the bottom of foundation beam, the influence of cross points on the two ends of the foundation beam and foundation beam is larger, and other parts of foundation were less affected. When there is no hole in the foundation, the stress at the bottom is always the compressive stress, at the top of the cross point is the compressive stress, and the top of the foundation beam is the tensile stress; Cave can change the original stress character and size of foundation beam; These rules can provide guidance for practical engineering design and reinforcement.