Detection And Influence Analysis Of Grouting Defects Of Reinforced Sleeve In Residential Buildings With Prefabricated Shear Wall On Longhua Road

In recent years,the prefabricated concrete structure system has developed rapidly and has been encouraged by the state.Compared with the traditional building structure,its advantages are more prominent,such as a higher degree of industrialization,fast construction speed,excellent quality,environmental protection and energy saving,etc.Among them,the sleeve grouting method is usually used when connecting the main reinforcement,and whether the grouting is full or not is the main constraint factor to ensure the mechanical properties of the joint.In real projects,there are usually cases where construction is not meticulous and supervision is not in place.Coupled with the limitations of factors such as workers and technical levels,the density of grouting cannot meet the requirements.At present,there is no information about the density in sleeve grouting construction.Form sound technical standards.There are few explorations on grouting defects in our country,and its restrictive effect on the seismic capacity of prefabricated concrete shear walls is not clear.As grouting sleeve connection performance is affected by the grouting operation quality,but the present methods of grouting quality detection have their own limitations and disadvantages,the grouting operation quality is difficult to detect,in addition to filling defect effect on the overall performance fabricated structure research also is less,which restricted the sleeve grouting technology in the application of prefabricated concrete structure.Based on the present situation,this article selects the current commonly used prefabricated shear wall socket grouting connection as the research object,starting from the steel sleeve fitting level,discusses the various types of grouting defects on the performance of the socket fittings and prefabricated shear wall specimen,and explore the effectiveness of the grouting defects NDT methods,the main work is as follows:In order to explore the X-ray detection and identification of sleeve grouting and verify the feasibility of adopting this detection method in the residential project of Longhua Road prefabricated shear wall structure,the grouting quality of prefabricated shear wall sleeve was tested on the construction site,and the forming quality of key joints was fully mastered,so as to ensure the stability and safety of the overall structure.Firstly,the basic principle of X-ray detection is introduced.Six grouting sleeves are made,and CT scanning is carried out by YXLON micro-focus X-ray computed tomography system,and the scanned 3D model is section-processed.X-ray has good interface recognition ability and can effectively distinguish steel sleeves,steel bars and grouting materials,and the defect position usually shows the highest blackness value,which is very easy to distinguish,and the defect distribution inside the sleeve is more intuitively understood.To study the effect of grouting defects on socket fittings mechanics performance,judge socket connector failure mode,based on the change of discharge plasma side bar anchorage length to equivalent substitution degree of filling defect,the grouting socket fittings to simulate monotonic tensile test,and through the comparative analysis to get the minimum discharge plasma side bar anchorage length.The finite element model of the connector is constructed through the ABAQUS simulation software,and the relative displacement between the steel bar and the grouting material is simulated.The parametric analysis method is used to discuss it,and finally the safety control parameters when the steel bar is fractured in tension are obtained.In order to explore the constraint of the sleeve grouting defect on the seismic capacity of the prefabricated concrete shear wall and the whole project,the finite element modeling of the prefabricated concrete shear wall containing this problem was carried out based on the ABAQUS simulation software.The Coulomb friction force is used to simulate the transition mode between the two parts;the equivalent substitution method is used to simulate the sleeve connection,and it is replaced by a spring element to simulate the difference of grouting defects when the latter stiffness parameter changes.And the changes of the key parameters of the model,such as bearing capacity,stiffness attenuation,energy dissipation performance,etc.,are comparatively studied when the defects are different.At the end,based on the above simulation results,a comparative study is carried out on the key performance parameters of the shear wall with different defects,such as hysteresis curve,stiffness error,bearing capacity,etc.,and the constraints of the defect on its seismic capacity are determined according to each parameter.In order to make up for this defect,the shear wall must be reinforced,and a targeted reinforcement scheme is provided,so as to be implemented and applied in this project,and even promoted to similar projects.