Experimental Study On The Tensile And Shear Properties Of The New Type Of Connector In The Precast Concrete Sandwich Wall

Precast concrete sandwich wall meets the requirements of the energy saving building, housing industry and has broad application prospects in China. Precast concrete thermal insulation sandwich wall structure system can make a complete prefabricated building with bearing and retaining members such as the outer wall which serves a maintenance function; the insulation layer and the inner wall(bearing function) and this constitutes the three major parts. The connector purpose is to ensure the stability of the outer wall under vertical load, transfer the shear stresses from the outer wall to the inner wall within the sandwich system as well as linking both leaves. Furthermore, the connector will bear and transmit the wind load and earthquake action of the outer wall, and ensure the proper functionality of the inner and outer walls. Therefore, the tensile and shear resistances of the wall are related to the safety and durability of the wall and relevant research is highly demanded in order to further comprehend the bearing capacity of the connector. In this report, the tensile and shear properties of a new type of composite connector used in precast concrete sandwich wall are studied. The tensile, shear and deformation capacities with the respective failure processes are obtained, and the finite element numerical modeling is carried out for the tensile properties of the new composite connector. The main research contents of this monograph are as follows:(1) The design and the tensile test of 24- precast concrete wall specimens with composite connector under unilateral tension and 24-specimens subjected to bilateral tension were carried out. The tensile bearing and deformation capacity and the failure mechanism of a new composite connector are obtained. Additionally, understanding the relationship between the distribution of steel bars and the position of the joints in the wall to the limit load and deformation capacity of the specimens is investigated. The test results showed that: The average ultimate tensile bearing capacity of the connector is 12.1k N ~ 27.3k N; failure modes are brittle and the failure mechanism of concrete is mainly presented. The relationship between the two positions of the connector and the reinforcing bar has no influence on the ultimate bearing capacity. However, the steel mesh can delay the process of pulling out the concrete.(2) The shear failure capacity and model of a new type of composite connector in the precast sandwich concrete wall were obtained by shear test, which were designed and manufactured by 24 shear test specimens. The results obtained are as following: The average shear strength of the connector is 15.5k N ~ 18.8k N which represents high security reserves.(3) By using the numerical finite element software ABAQUS, a model and an analysis were performed for the pull-out test component. The influences of different strengths for the concrete grade and different connectors fixed at different depths are further analyzed to establish the bearing capacity of the connector. The simulation results are compared with the experimental results, which confirm the validity of the finite element model. In addition, the results show that when the depth of the connector is 30~50mm, the diameter of the connector cross part is 4~8mm, the ultimate tensile bearing capacity of the specimen being proportional to the depth and diameter of the connector cross part.