Study On The Single Side Eccentrically Compressed Load Bearing Capacity Of Thin-Walled Reinforced Concrete-Filled Steel Tube Composite Structure

In order to accelerate the development of China's inland waterways,the thin-walled reinforced concrete-filled steel tube composite overhead-vertical structure,as a new type of wharf structure,has been applied to practical engineering.In practical engineering examples,most of the composite components are in an eccentric compression state due to the deviation of the manufacturing,the deviation of the axis line,the synergistic force of the connection structure and the unevenness of upper loading.At present,the research on the eccentric compression bearing capacity of the thin-walled reinforced concrete-filled steel tube composite structure for the wharf structure has not been discussed.In view of this,this paper relies on some research contents in the Science And Technology Ministry Of Transportation.,that is about the study on the technical and mechanical characteristics of the overall safety assessment of the existing high pile wharf structure.The main contents and results of this paper are as follows:First,the test scheme for the thin-walled reinforced concrete-filled steel tube composite structure is designed: The principle of similarity ratio in laboratory model test of hydraulic structures,determination of the properties of each material,loading scheme and arrangement of measuring points,the test process,the content needed to test and the need to deal with data processing,material statistics,material performance test,specimen production,test piece maintenance and so on.According to the transform of steel tube and eccentricity parameter,5 model columns and matching form-work were designed and made.Second,Through indoor model tests of model columns,the whole process of loading and failure of composite components is studied,and the failure modes of specimens are investigated.The influence of various parameters on the bearing behavior of composite components is discussed.The results show that:(1)The increase of the thickNess of the steel tube improves the bearing capacity of the composite structure,which is constrained by the material itself and the steel pipe to the core concrete,so that the concrete is in the three direction compression state.The brittleness and deformation of the concrete are restrained,and the bearing capacity of the component is improved;(2)The eccentricity ratio increases,the ultimate bearing capacity of composite structure decreases,the elastic stage percentage is lower,and the top surface of the concrete column lateral tension cracking of a greater degree of steel casing of the circumferential strain distribution is not balanced.(3)When the eccentricity is 0.25 to 0.5,there is a boundary failure value,which makes the reinforced concrete yield just when the compression concrete is crushed.Next,in order to verify and deepen the research of the thin-walled reinforced concrete-filled steel tube composite overhead-vertical structure,based on the experimental data and analysis,the finite element analysis software ABAQUS is used to simulate the model test.The results of numerical solution show that:(1)under ideal condition,the ultimate load carrying capacity of the members increases linearly with the increase of the thickness of the steel tube wall of the thin-walled concrete-filled steel members.(2)The eccentricity increases,composite member by top to the bottom of the column transfer strain range deeper.And the area of tension in the tension zone increases with the eccentricity when the ultimate bearing capacity is reached.(3)When the eccentricity is from 0.45 to 0,the first derivative of the increase rate of of the bearing capacity of the unidirectional eccentric compression structure increases.Meanwhile,when the eccentricity is from 0.45 to 0.7,the first derivative of the reduction rate of the bearing capacity of the unidirectional eccentric compression structure increases.