Seismic Analysis For A New Type Of Prefabricated Hollow Plate Stairs

The prefabricated concrete hollow stairs is a new stairs and is fit to be appliedin housing industrialization, whose hollow part is composed of symmetrical roundhole on its section. The PC stairs have the characters of light weight, large span,convenience of construction and good applicability, which is especially suitable forscissors-type stairs in residence structure. The stairs is an important passway forescaping in earthquake. At present, the seismic research on PC stairs is little. So theseismic study of the new PC hollow stairs is required.In this paper, the research is mainly focused on the numerical simulation of thePC hollow stairs under static effect, conventional earthquake effect and rareearthquake effect.The basic points for numerical simulation by finite element software ABAQUSis introduced, which includes: the property of materials, the establishment ofboundary conditions, the choice of element types, etc. Under the basement ofverifying the validity of reinforced concrete model, static effect is applied on PChollow stairs model and the influences of rebar arrangement and boundaryconditions to the vertical displacement are analyzed in details.The12-stories shear wall residential structure is established and is analyzed byvibration mode decomposition response spectrum under conventional earthquake inSATWE, from which the maximum displacement between layers of stairs is pickedup. The above pick-up outcome is applied on the boundaries of stair entity model bydiaplacement effect style and is numerically simulated in ABAQUS. The simulationresults is analyzed from vertical displacement, the maximum principal stress andrebar Mises stress and it is concluded that the PC hollow stairs meets the demand ofelastic deformation; Prepared holes are prone to generate stress concentration andcracks; Stirrup effect is obvious; Compared with one end fixed and the other endhinged of boundary condition, the hinged stairs have better performance.The above12-stories shear wall residential structure is analyzed byelastic-plasic time history method and the most unfavorable displacement timehistory response at ends of stairs is extracted. Then the response is applied on both borders of stairs model to analyzed by dynamic elastic-plasic method in the finiteelement software ABAQUS. From vertical displacement, energy dissipation, themaximum principal stress of concrete, damage factor and rebar Mises stress, thispaper analyzes the damage and failure modes of the PC hollow stairs and theinfluences of rebar arrangement and boundary conditions to the anti-seismicbehavior. Results show that under rare earthquake, in addition to show consistentwith ordinary stairs failure modes, the PC hollow stairs also occurs some uniqueform of damagem, such as the prepared hole damage is serious, the top part ofscrews occur large deformation.