Experimental Study For The Bearing Behavior Of Super Frame Structure Based On Foundation’s Unequal Settlement

With the development of times and economy in our country, contradiction between the increasing of urban construction strength and the decreasing of construction land becomes increasingly serious, so people pay attention to underground engineering. The influence on the land and the surrounding environment becomes more significant because of more and more development of underground engineering. In addition, there exist many special soils such as collapsible loess and foundation in mountain area. These problems can cause uneven settlement, causing the damage or even destroy the upper structure. Reinforced concrete frame structure is one of the most common structures in our country. There are many theoretical analyses on the impact of uneven settlement on upper structure, but test and observation is seldom. The method based on theoretical analysis combined with experimental study can systematically research the influence of uneven settlement on structural internal force and deformation, which has great significance for people’s life safety and urban construction safety.The main content of this paper are as follows:1. Introduce the research purpose and significance of uneven settlement, the collapsible loess ground, foundation in mountain area, and other special soils. The causes of uneven settlement and prevention measures are described. In addition, introduce the domestic and foreign research status in this respect.2. Introduce the significance of nonlinear finite element analysis on reinforced concrete, similarity principle of structural tests, the model (specimen) design, and common loading method of structural tests, the constitutive relations and failure criteria of concrete.3. Introduce the program of Ansys software, then modeling and analysis on existing building. Put forward five kinds of working condition. The structure has no sedimentation on working conditions (SI), and settlement extents from the middle column feet to the side column feet (S2-S5conditions). Study the internal force and deformation of the upper structure under each condition. Analyze the relationship and difference between working conditions, and conclude the change rule of internal force and deformation. 4. The1/3scale model tests have been carried out, namely using the side column settling test and the middle column settling test to research load bearing properties of the upper structure when foundation occurs uneven settlement. Observe the performance and final damage of specimen in the process of loading. Get the limit of uneven settlement, the allowable value of the differential settlement between adjacent column and the tangent value of beam angle. For settlement of side column, short beam is at bearing capacity limit state when tangent of Angle is1/54.For settlement of middle column, tangent of short beam angle is1/50at this state. When the side column settlement is97mm, the crack of subsidence column concrete means the specimen failing. While the settlement of middle column is84mm, the specimen2fails. In the test, the concrete first crack and fail at the weak parts, this can be taken as reference to the actual design, construction, examination and reinforcement, to ensure the safety of the project.