Experimental Study On Seismic Performance Of A New Prefabricated Column Foot Of The Low Axial Compression Ratio

Prefabricated frame structure has many advantages and is widely used.The development of our prefabricated structure is in its infancy.A new type of column footing node for assembly frame is proposed in this paper,with conducting full-scale contrast tests and finite element simulations.The main work and achievements of the paper are as follows.(1)A low-cycle reciprocating test of three low axial compression ratio column foots with non-adhesively column foot,traditional fabricated column foot,and cast-in-place column foot is performed.By comparing the hysteretic performance,bearing capacity and energy dissipation capacity of the three,the tests show that the prefabricated column foot proposed in this paper has equivalent bearing capacity and energy dissipation capacity with cast-in-place column foot.The unbonded structure of foundation reinforcement improves the collapse resistance and deformation capacity of column base,and it has similar load carrying capacity and energy dissipation capacity with traditional fabricated column foot.(2)The calculation model of the fabricated column is set up,and numerical simulation of the experimental model is performed by OpenSees.The calculated results agree well with the hysteretic curve of the test results.The influence of the non-adhesively length of steel bar on the performance of column foot is simulated.The results show that the peak load capacity and the plastic residual deformation decrease with the increase of the non-adhesively length.A simplified formula for calculating the strength of inner core concrete of grouting sleeve is put forward.The numerical simulation analysis on the influence of the core concrete strength on the horizontal bearing capacity of the column foot and the determination of the calculation range of the concrete core area inside the grouting sleeve is carried out.The results show that the strength of core concrete has less contribution to the horizontal bearing capacity of columns under low axial compression ratio.The calculation range of concrete core area in grouting sleeve is determined.(3)Reference to the corresponding specifications,the design method of the column base is established,including calculation of ultimate load capacity of normal section and calculation of bearing capacity of horizontal joints.The construction measures of the new assembled column base are also presented.The new local non-adhesive connection method proposed in this paper can be used as one of the connection methods of column and foundation,which is under the condition of the low axial compression ratio column in the prefabricated frame.The paper provides the corresponding basis for the engineering application of the connection method.