Research On Seismic Behavior Of PP-ECC Piers

Strong earthquake has brought great threat to people's life and property security.As the hub of "lifeline" project,bridge will cause huge direct and indirect loss and repair difficulty once it encounters earthquake.The investigation of earthquake damage at home and abroad shows that the lack of ductility of pier is an important factor in its serious failure,and the main reason is the lack of good deformation capacity in the plastic hinge area of pier.In order to improve the ductility of RC pier column,the concrete of ordinary RC pier column is replaced by high-ductility PP-ECC(polypropylene engineering cement-based composite material)and named as PP-ECC pier column.The anti-seismic design method of PP-ECC pier column is constructed.The difference of the PP-ECC pier column and the corresponding RC pier column in the seismic performance is compared and analyzed in comparison with the nonlinear seismic time-history response of a pier column and a bridge,and the effectiveness of the design method is also discussed.The main contents of this paper are as follows:(1)In this paper,the formulas for calculating the yield moment,the peak bending moment,the yield curvature and the peak curvature of the plastic hinge region of the PP-ECC pier column are derived,and the seismic design method of the PP-ECC pier column is proposed.(2)four pier column models are designed and fabricated: one RC pier column model and three PP-ECC pier column models(150mm thick PP-ECC shell wall,100 mm thick PP-ECC shell wall,50 mm thick PP-ECC shell wall),respectively,the plastic hinge zone is 150 mm thick PP-ECC shell wall,100 mm thick PP-ECC shell wall,and 50 mm thick PP-ECC shell wall,respectively.Based on the experimental results of pseudo-static reciprocating loading,the differences in failure mechanism,bearinging capacity,energy dissipation capacity,especially ductility of various pier-column models are compared and analyzed,and the effectiveness of seismic design method for PP-ECC pier-column is discussed to a certain extent.(3)based on the experimental results of pseudo-static reciprocating loading,the force-displacement three-fold hysteretic model of four pier-column models is constructed.The nonlinear seismic time-history response of each pier-column model is analyzed by selecting typical ground motion under the condition of ?-? site,and the ductility and energy dissipation capacity of PP-ECC pier-column model are discussed in depth.(4)taking a three-span linear bridge with single column pier as an example,the finite element models of RC pier-bridge and PP-ECC pier-bridge are established.The responses of piers and supports are compared and analyzed,and the difference of seismic performance between the two types of bridges is discussed.