Experimental Study On Effects Of Grouted Defects On Behaviors Of Grout Sleeve Splicing And Specimens

Industrialization is an important structure system for construction of the residential buildings.The assembled pre-cast concrete structure system is an effective and suitable method for industrialization.The reliable connection between adjacent components is the key point which will considerably influence the integrity and seismic capacity of assembled structure.The research of this paper is based on National Science and Technology Support Program-the standard system and the acceptance of construction quality of industrialized buildings.The program number is 2016YFC0701805.The dissertation attempts to find out the effects of different grouted defects on the behaviors of grout sleeve splicing and prefabricated assembled columns and beams and to explore the detection of grouted defects.Firstly,the author tried to analyze the forming mechanism of grouted defects and classify their categories by site investigation of building projects and the test of property of grouting material.Secondly,tens of specimens were manufactured and tensioned with testing machine monotonically to clarify effects of grout defects on mechanical behaviors of grout sleeve splicing for reinforcing bars.Thirdly,more than 20 specimens were fabricated and exanimated under the X-ray defect detection system.The primary purpose of the non-destructive test is to evaluate the applicability of X-ray on the detection of grouted defects.Fourth,quasi-static tests of five assembled concrete column specimens with shear span ratio of 5.0 were carried out.Among the five assembled column specimens,the grout sleeves of four specimens contain different types of defects and the other one contains no defects.Fifth,monotonically static test of two assembled beam specimens with vertical reinforcements spliced by grout sleeves were performed,aiming at studying the influence of grouting direction.The test results indicate that: 1.the major factors of grouted defects involves the locations and the dimension of grouted defects,reinforcement eccentricity,grouting directions,and grouting duration which will induce the declination of anchoring performance of grouting materials.2.Central defects and horizontal defects have greater influence on mechanical behaviors than end defects and vertical defects do when they have same dimension.Compared to axial specimens,the load bearing capacity and deforming capacity of specimens with reinforcement eccentricity decrease much faster.3.X-ray defect detection is an applicable method for non-destructive testing of grouted defects.It can identify the interface between sleeves and grouting materials,the interface between steel bars and grouting materials and a defect with dimension of 1mm ?4mm.4.The impact of grouted defects on assembled columns mainly results in the reduction of load bearing capacity and ductility,earlier stiffness and strength attenuation and less energy dissipation during the entire loading process.The top lateral force-displacement hysteretic curves of assembled columns will have a more obvious pinching effect if they contain bigger defects.5.According to static test,the assembled beam specimens can fulfill the demand of load bearing capacity and ductility,implying that grout sleeves splicing can effectively transfer stress and strain.Based on the data of the tests,this dissertation poses different models to fit the effects of grouted defects on grout sleeve splicing specimens.Besides,non-dimensional analysis of the performance parameters of assembled structure is applied.It is very helpful for the further study on the seismic performance of the prefabricated assembled concrete structure and it also provide a reference for quality acceptance of assembled structure buildings.