Seismic Performance Research On Fabricated Concrete Shear Wall Structures With Sleeve Grouting Defects

Due to the advantages of green,environmental protection and high efficiency,the fabricated concrete structure meets the requirements of industrialiazation of buildings and has developed rapidly since the beginning of the 21 st century.The precast concrete shear wall structure means that some or all of the reinforced concrete shear walls are prefabricated at the factory,transported to the site,and the overall structure is formed by reliable connection.Grouting sleeve connection,as a connection technology widely used in prefabricated buildings,has played a huge role in the construction of fabricated structures at home and abroad.Sleeve grouting compactness is the key factor to ensure the mechanical properties of the joint.Actual engineering conditions often have problems such as neglect of management,extensive construction,poor supervision,and low level of construction refinement.Due to human factors and technical level restrictions,the grouting compactness cannot meet the relevant standards.At present,there is no perfect specification for the compactness of the grout in the sleeve connection in China.There are relatively few studies on grouting defects at home and abroad,so the influence of sleeve grouting defects on the seismic performance of fabricated concrete shear walls is not clear.In order to research the influence of grouting defects on the mechanical properties of the sleeve joints,the author changed the anchor length of the upper rebar to replace the degree of grouting defects,and carried out the monotonic tensile test,large deformation repeated tension and compression test and high stress repeated tension and compression test on the grouting sleeves.Through out comparison and analysis,the minimum anchor length of the upper rebar was received to meet the requirements of Technical specification for mechanical splicing of steel reinforcing bars(JGJ107-2016).The author used the ABAQUS software to establish grouting sleeve finite element models.Compared with the actual test results,the parameters of the anchor length were analyzed to obtain the final safety control indicator.With the purpose of studying the influence of grouting defects on the seismic performance of fabricated concrete shear walls,the low-cycle reciprocating loading test was carried out for the prefabricated shear wall members which have lower anchor length than the safety control indicator.Considering the difference of location and compactness,6 pieces of shear walls with different grouting defects and 1 piece of full-grouted wall were designed.The bearing capacity,stiffness degradation and energy consumption of this seven shear wall specimens were compared and analyzed.By means of the ABAQUS software,the shear wall finite element model was established to verify the experiments.The cohesive-behavior model was simultaneously applied to simulate the interface contact behavior between shear wall and ground beam.As the substitution of grouting sleeves,spring units were used to realize the connection of upper and lower steel bars.Correspondingly,the author modified the stiffness coefficient of the spring units to change the compactness of grout.Finally,combined with the test and numerical simulation results,the failure mode,hysteresis curve,stiffness degradation,bearing capacity and other indicators of the shear wall specimens with different grouting defects were compared and analyzed.According to different energy consumption indexes,the influence of grouting defects on the seismic behavior of fabricated concrete shear walls was given as well as the reinforcement suggestions.