Research On Bearing Behavior Of Reinforced Concrete Column-isolated Footing Sub-structures

Choosing an appropriate foundation model to estimate the constraint of the soil medium to isolated footing is an important factor in analyzing the bearing capacity of reinforced concrete column-isolated footing sub-structures.The Winkler foundation model is an ideal elastic foundation model based on the simplification of elastic mechanics.A simulator of elastic foundations can be proposed using wood and rubber,The load-bearing performance test of reinforced concrete column-isolated footing sub-structures on elastic foundations can be carried out using this simulator,The failure mode of sub-structures under axial and lateral loads are analyzed.In this paper,the load-bearing performance tests of reinforced concrete column isolated substructures with different reinforcement ratios of foundation under the joint action of vertical and horizontal loads on the top of the column have been carried out.The experimental date such as cracks,failure model,control section,bearing capacity curve,deflection of foundation and subgrade reaction are obtained.the substructure with the smaller reinforcement ratio are failed with flexural-shear failure model on foundation section,and the substructure with larger reinforcement ratio are failed with flexural failure model on foundation section.And the reinforcement ratio has little effect on embedded property of bottom column before isolated footing yield,but it will drops sharply after isolated footing yield,especially for the substructures with smaller ratio of reinforcement.The formula for calculating the flexural capacity of independent foundation under eccentric load is derived by the yield line theory,and the formula is evaluated by the substructure bearing capacity of the bending failure in the test.The spring element in ABAQUS is used to simulate the constraint of elastic foundation to the foundation.And the accuracy and applicability of the finite element model are verified by experimental date.The parameters of the foundation coefficient,axial compression ratio,foundation height and concrete strength are analyzed to obtain the failure section and failure form of substructure.The change of foundation coefficient has a great influence on the constraint ability of the bottom column while the value is small,and it has little influence when foundation coefficient reach a higher value.With the increase of the axial compression ratio,the bearing capacity increases first and then decreases for the changes of structural failure model and section.When the foundation height is small,the bearing capacity of the column cannot be fully exerted for the failure of foundation section.After the foundation height reach a higher value,it has little influence on the bearing capacity.The increase of the strength of the concrete will have little effect on the bearing capacity of the substructure if punching and shearing failures of foundation are not occurred.