Study On Seismic Performance Of Prefabricated CFST Double-column Piers

With the advantages of high strength,light quality,good ductility,fatigue resistance and impact resistance,concrete-filled steel tube has been widely used in China's engineering construction.At the same time,it has become a trend of modern bridge engineering to replace the labor intensive manual production method with the technology integrated scale chemical plant,replace the site wet operation construction with the industrial product on-site assembly and realize the green construction mode of the bridge components production and assembly.At present,the research on the assembly of bridge pier is mainly focused on precast reinforced concrete bridge piers,However,there are few studies on prefabricated concrete filled steel tube piers,especially double-column piers.In order To promote the application of concrete-filled steel tubular double-column piers(DCP-CFST)in bridge structures in earthquake areas,this paper has completed three low-cycle reciprocating load tests of three “wet connections” and three “dry connections” prefabricated DCP-CFST,and based on finite element software ABAQUS and OpenSEES,a numerical simulation method for prefabricated DCP-CFST was developed.The main contents of the dissertation are described as follows:(1)The experimental study on the low cycle reciprocating load of DCP-CFST connected with cast-in-place,embedded and U-type anchor bar connection was completed,the effects of different wet connection modes on the hysteresis performance,bearing capacity,ductility,energy dissipation and stiffness of the double column piers were analyzed,and the calculation method of seismic bearing capacity of different wet connection specimens was discussed.The results show that all the specimens show a good failure mode of plastic hinge at the end of the column,and the embedded double column pier can achieve the aseismic performance equivalent to the integral cast in place.The bearing capacity and energy dissipation capacity of the U-type anchor bar jointed DCP-CFST are lower because of the rigidity of the U-type anchor bar connection is lower than the integral cast in place node and the embedded connection node,but the ductility is better than the previous two.The results obtained by the proposed method are in good agreement with the measured data.(2)This essay tested three concrete segmental two-column piers with steel tube connected by the high-strength prestressed rebar under low cycle loading.The test aimed to study the effect on the seismic behavior of two-column pier by the number of segments and types of steel plate energy dissipaters,and discussed calculation method of seismic bearing capacity for different dry-connections of specimens.The research showed that the number of concrete segments with steel tubes had less effect on the seismic behavior of specimens,adding plate consumption in two-column piers can improve the bearing capacity,energy dissipation ability and stiffness of the two-column pier,as well as the residual displacement after earthquake correspondingly.The research also compared the result calculated according to the proposed seismic design method and the experimental data,which confirms the proposed seismic design method found can predict the test results well.(3)Based on ABAQUS finite element software,this essay simulated the "wet connection" concrete two-column piers.The result showed the Pushover curve matches the test skeleton curve well.Subsequently,the research discussed the hysteresis performance simulation method based on OpenSEES software,and the hysteresis curve is similar to the experimental results.The above work can provide useful reference for the research of concrete two-column piers.