Analysis Of Mechanical Behavior Of SMA As Shear Connector In Concrete Frame-Filled Steel Structure

At present,people are increasingly demanding on the seismic performance of building structures,and a new type of structure-the partially-restrained steel frame with solid reinforced concrete filled wall(PSRCW)came into being.The PSRCW structure which uses the reinforced concrete shear wall to fill the steel frame can save the steel and reduce the cost.The lateral stiffness of the reinforced concrete shear wall is large,which makes up the disadvantage of the lateral stiffness of the steel frame and reduces the lateral movement.In the PSRCW structure,the role of shear connectors is critical.The traditional steel shear connectors are prone to low cycle fatigue damage,therefore,it is very urgent and necessary to find new shear connectors.The shape memory alloy(SMA)is a kind of intelligent material.It ’ s shape memory effect,strong deformation recoverable performance,good anti-fatigue performance and many other advantages make it possible to use as shear connectors in the PSRCW structures.From the point of view that SMA has good deformation and fatigue resistance,the SMA with super elastic was used as the shear connectors in the PSRCW structure in this paper and carried the following tasks in order to have a further study on the seismic performance.(1)The characteristics of PSRCW structure and the research status of seismic performance were summarized;a new type of SMA shear connector was put forward,at the same time,the properties of SMA and its application in civil engineering were introduced.(2)Six specimens were designed and manufactured.The test equipment,the arrangement of the measuring points and the loading scheme were introduced.The mechanical properties of the steel,concrete and SMA shear connectors were tested.(3)The six specimens were studied by the pseudo static test and the influence of four aspects including the types of shear connectors,the dimension of shear connectors,the arrangement ways of shear connectors and the forms of filled walls on the seismic performance of specimens was analyzed.(4)It was shown that from the point view of the overall performance,the PSRCW structure with shear connectors made of SMA had many advantages:the force on the structure was more uniform and the energy dissipation capacity was strong;it had good ductility and self repair ability;the increase of the diameter of shear connectors enhanced the bearing capacity of the structure;the arrangement of the SMA shear connectors had little effect on the stiffness and strength of the structure,but the energy dissipation capacity,ductility and integrity were improved;the SMA shear connectors connected with the frame beam were more important to the shear performance of the structure,and the SMA shear connectors connected with the frame columns were more important to the integrity of the structure;the setting of the dark vertical seams greatly weakens the strength and stiffness of the filled wall,reduced the energy dissipation capacity of the structure,but improved the ductility of the structure.It was also shown that from the point view of the local performance,the SMA shear connectors reduced the slippage and separation between the filled wall and the middle beam and ensured that the structure had good ductility;the increase of the diameter of shear connectors enlarged the interface slip between the filled wall and middle beam;the setting of the dark vertical seams reduced the slide between the filled wall and the middle beam and reduced the deflection of joints between the beam and column.