Research On Bearing Capacity Of Headed Bars With Anti-floating Bolt

With the continuous development of anchor bolt technology,the number of successful engineering applications is increasing,and the theoretical research about it is also deepening.However,most of the existing researches focus on the physical properties of the anchor bolt and the interaction effect between the expanding bolt and the foundation soil and other mechanical mechanisms of the bolt itself,while almost no relevant scholars and engineers have carried out relevant researches on the connection effect between the bolt body and the structure.In order to solve practical engineering problems and provide better theoretical guidance for construction and production at site,this paper studies the bearing capacity of the headed bars with rock bolt connected with the bottom plate of concrete structure by using steel bar as the main reinforcement.(1)First of all,in this paper,18 pcs of headed bars are designed and completed in full scale drawing tests.By using the ultimate bearing capacity measured in the test and the displacement and deformation recorded in the test,the factors that may affect the bearing performance of the rebar anchorage plate of the rock bolt are analyzed and studied.The influencing factors analyzed in the full scale test mainly include the thickness of concrete floor of building structure(h),punching and cutting height of anchor plate(h0),side length of anchor plate,connecting spiral stirrup of anchor plate,upper and lower main reinforcing-bar of the structure bottom plate,etc.Through this experimental study and analysis,the following conclusions are drawn:1)It can be concluded from the test that the failure forms of the headed bars are mainly divided into two types: one is the punching and cutting failure of the concrete bottom plate of the headed bars,the other is the shear failure of the steel pad plate of the headed bars,and most of the test failure forms are the combination of the two types.2)When the other conditions are same,the impact of punching height on the bearing capacity of the headed bars is obvious.The larger the cutting height,the greater the bearing capacity that the headed bars can bear.Therefore,when the thickness of the bottom plate is constant,the ultimate bearing capacity of the headed bars can be significantly increased by increasing the punching height.3)Because the punching height increases when the thickness of the concrete floor is increased,the ultimate bearing capacity of the headed bars can also be increased by increasing the thickness of the concrete floor.4)When the other conditions are same,the side length increasing of the steel pad plate can increase the ultimate bearing capacity of the headed bars to a certain extent.5)When other conditions are same,the setting of spiral stirrups can significantly increase the ultimate bearing capacity of the headed bars.6)The ultimate bearing capacity of the headed bars is not affected by whether the anchor bar is installed in the upper and lower layer of the structural floor,but it is helpful to reduce the deformation of the headed bars.(2)In addition,this paper also deduces the calculation formula of the ultimate bearing capacity of the steel pad plate in the reinforcement anchorage plate,and brings the data of the field drawing test into the derived formula for checking calculation.The calculation results show that the formula is consistent with the field test results,which can provide theoretical guidance for practical engineering production.