Seismic Behaviour Of Precast Concrete Beam-Column Joints Using Double Grouted Splice Sleeves

Precast concrete frame structure is an important direction for the development of building industrialization of China because its components are convenient manufacturing,easy standardization and quick assembly.However,the connection between precast concrete beams and columns is one of the biggest weaknesses.At present,the connection between precast concrete beams and columns has many problems such as high installation accuracy,difficult quality assurance,easy corrosion,large amount of steel and post-pouring concrete,which restrict the popularization and application of precast concrete frame structure in China.To address these disadvantages of existing precast beam to column joints,a new precast beam to column connection connected by double grouted sleeves was proposed in this thesis and its seismic performance was investigated.In order to reduce the production cost of grouted sleeve,two types of low-cost grouted sleeves(i.e.,GSW and GSWT)were also proposed in this thesis,and the mechanical behaviour of them was studied.The main work and conclusions are as follows:(1)An experimental study on mechanical behaviour of twenty-two grouted sleeve splice specimens including nine GSW splice specimens and thirteen GSWT splice specimens was conducted.The test results indicated that the performance of GSW and GSWT met the JGJ107-2010 strength requirements of the splice grade Ⅰand the required anchorage length of spliced bar was about 6-6.4 times the diameter of spliced bar.(2)The tensile capacity of the splices was increased by 25.5% with increasing diameter of the spliced bar.Therefore,the tensile capacity of the splices can be improved and the length of the grouted sleeves can be shortened through increasing diameter of the anchorage segment of the spliced bar.Both length and slope of the wedges had an impact on the tensile capacity of the splices and the tensile capacity of the splices increased with the increase of the slope and the wedge length.Because of the good performance of wedges threads did not significantly improve the tensile capacity of the sleeve but improve the bond performance and bearing capacity in non-wedge segment of the sleeve.Based on the dimensional parameters and test results of the splice specimens,two models were proposed to predict the bond strength and the bearing capacity of the splices respectively.The prediction results are in good agreement with the test results.(3)Based on the variety of sleeve types,assembly distances and spliced bar diameters,one cast-in-place control specimen and six precast concrete beam-column joints connected by double grouted splice sleeves were fabricated.Through static and pseudo static tests,the failure modes of the specimens were studied and the seismic behaviour(e.g.,load-displacement curves,skeleton curves,ductility and energy dissipation capacity,etc.)of the specimens were analyzed.The results showed that the hysteretic curves of the joints proposed were full and the seismic behaviour of them was good.(4)When the assembly distance was 0 mm,the crack distribution range of the precast specimens was basically the same as that of the cast-in-place specimen.However,the plastic hinge length of the precast specimens with assembly distance 0 mm was shorter than that of the cast-in-place specimen and the damage of them was lighter.When the assembly distance was increased from 0mm to 425 mm,the length of the plastic hinge of the precast specimens increased significantly.However,the crack distribution range of the specimens with assembly distance 425 mm was shortened by 45%.The bearing capacity of the precast specimens and the cast-in-place specimen was basically the same.When the spliced bar diameter was increased from 16 mm to 18 mm,the bearing capacity was increased by 20.4% and the total accumulated energy consumption was increased by 64.8%.The ductility of the precast specimens was better than that of the cast-in-place specimen while the energy dissipation capacity of the precast specimens was lower than that of the cast-in-place specimen.Increasing assembly distance can improve the ductility and energy dissipation capacity of the precast specimens.Providing threads in the non-wedge segment of GSW would reduce the ductility and energy dissipation capacity of the precast specimens.Finally,based on the mechanical characteristics of the precast specimens,the strength calculation method was given,and the calculated results were in good agreement with the experimental results.On the basis of summarizing the work of this thesis,the research prospect of this topic was put forward.