Multi-Directional Force Characteristics Of Post-Installed Connection Group Anchors And Development Of Design Software

Post-installed connection has the advantages of simple construction and flexible use,and has been widely used in new construction projects and existing structure reinforcement and reconstruction projects at home and abroad.In the design of postinstalled connection,accurately calculating the internal force of anchors is crucial.However,the current specifications at home and abroad for the analysis method of group anchor tension under multi-directional load are not clear,and the analysis method based on the assumption of rigid baseplate ignores the out-of-plane bending deformation of baseplate,which cannot truly reflect the stress situation of the anchors and may create safety hazards.In response to the above issues,this article conducts a systematic study on the tensile analysis method of post-installed connection group anchors under multi-directional forces and different baseplate stiffness assumptions.In addition,in order to help domestic enterprises get rid of the dependence on foreign anchor design software,the research group was commissioned by Shanghai Xiangrui Fastener Co.,Ltd.to develop the first post-installed anchor design software in China.The research results of this paper can not only supplement and improve the existing norms,but also can be transformed into practical applications to promote the development of post-installed connection industry.The specific research contents and conclusions are as follows:(1)Based on the analysis method of group anchor tension when the rigid baseplate is subjected to unidirectional bending in the current Chinese and European norms,the theoretical analysis method of group anchor tension when the rigid baseplate is subjected to multi-directional loads is improved.The accuracy of the method is verified by comparing with the calculation results of foreign mature industry software.(2)In order to study the actual stress of anchors,a finite element analysis method of group anchor tension based on elastic base plate assumption is proposed.Based on the finite element software ABAQUS,a simplified numerical model of the postinstalled connection joint is established,which can quickly analyze the force of the anchors.The accuracy of the numerical model is verified by comparing with the experimental results.(3)Comparing the tension analysis results of group anchors with different baseplate stiffness assumptions,it is found that the elastic deformation of the baseplate will significantly increase the anchor tension force,especially the maximum tension force of the single anchor,which brings potential safety hazards to the connection joint.In addition,the amplification coefficients of the elastic deformation of the baseplate on the maximum tension of the anchor and the total tension of the group anchor are proposed respectively,and the influencing factors of the amplification coefficient are studied.Based on the analysis method of multiple linear regression,the prediction equation of amplification coefficient is proposed.(4)In order to make up for the gap in the anchor design software in China,based on the research results of this paper and the summary and understanding of the current specifications,the first anchor design software in China was developed.The software can quickly and accurately calculate the internal forces of anchors under multidirectional loads and considering different baseplate stiffness assumptions,and perform safe and reliable checking calculations on various possible failure modes,thus providing an important reference for the design of post-installed connections.