Research On The Influence Of Anchor Reinforcement Parameters On The Tensile Performance Of Chemical Anchor Bolts

The post-planting anchor bolt technology is widely used in the reinforcement of bridges,tunnels,and buildings due to its flexible layout and easy construction.The continuous increase in the number and service time of engineering structures such as traffic infrastructure,bridges and tunnels has made post-anchor bolt technology one of the important means for anchoring reinforcement members on existing structures in later reinforcement or reconstruction projects.It plays a fundamental role in engineering.The existing research and design methods(ACI318,ETAG001,JGJ145,GB50367)related to post-plant anchor bolts all adopt the research results based on plain concrete anchors,ignoring the influence of the reinforcement in the anchors on the anchoring system,and cannot fully reflect the engineering reality.condition.The brittle failure characteristics of the post-plant chemical anchor anchor system when the anchor depth is less than 15 d,and the inaccurate design of these methods may cause serious problems.In this paper,the post-plant chemical anchors are studied under the condition of anchor reinforcement,which provides a more accurate design method reference for post-plant chemical anchors,which has theoretical significance and engineering application value.The main research contents and results of this paper are as follows:(1)The related research results of post-anchor bolts at home and abroad are systematically analyzed,and the failure mode and force transmission mechanism of postanchorage are summarized by collating and analyzing a large amount of test data of predecessors under different conditions.Discussed and evaluated the use conditions and error size of the main existing ultimate load-bearing capacity description models.(2)By sorting out a large number of reinforcement engineering design documents,the application scenarios of post-planting anchor bolts in structural reinforcement were classified,and based on the classification,the parameters of the steel bar under the condition of anchor body reinforcement were clarified: the spacing of longitudinal bars,Longitudinal reinforcement diameter,stirrup spacing and other reinforcement parameters are analyzed,and 6 sets of working conditions are designed for the three reinforcement parameters.(3)Based on the reinforcement method of common rectangular cross-section beams,the test of the influence of reinforcement conditions on the tensile performance of chemical anchors is designed,and the reinforcement parameters such as the longitudinal reinforcement spacing,longitudinal reinforcement diameter,and stirrup spacing are considered for a total of 6 groups.30 pullout tests of chemical anchor bolts.The following conclusions are obtained through the pull-out test: the change of the longitudinal bar spacing increases the tensile performance of the chemical anchor bolt by 7%-47%,and the change of the stirrup spacing increases the tensile performance of the chemical anchor bolt by 3%-8 %;the change of the longitudinal rib diameter increases the tensile performance of the chemical anchor by 1%-5%.The longitudinal reinforcement acts in concert with the concrete to take part of the tensile force instead of the concrete,which directly improves the tensile capacity of the base material.The ribs mainly constrain the deformation of the concrete base material,so that the concrete base material is in a multidirectional tension state,thereby indirectly improving the tensile strength of the base material.(4)Non-linear numerical analysis is carried out by considering the difference of reinforcement parameters,and the control variables of the 6 groups of tests are carried out based on the different reinforcement parameters such as the spacing of longitudinal reinforcement,the diameter of longitudinal reinforcement,and the spacing of stirrups,starting from the internal force of the reinforcement.It analyzes and compares the difference between the test results and the numerical simulation results,and analyzes the effects of the longitudinal reinforcement spacing,longitudinal reinforcement diameter,stirrup spacing and other reinforcement parameters on the tensile failure mode,mechanical mechanism,and ultimate bearing capacity of chemical anchors.,Verifying the correctness and rationality of the analysis results.(5)Based on the mixed failure mode and considering the reinforcement effect of the reinforcement parameters on the tensile performance of the base material,the calculation method of the ultimate bearing capacity of the chemical anchor in the case of the base material reinforcement was revised,and the influence of the reinforcement parameters was proposed.The calculation method of the correction coefficient,and the comparison of the corrected calculation results with the test data found that the error is between 1%and 6%,which is a high degree of agreement.