Shaking Table Test And Finite Element Analysis Of Sliding Prefabricated Stairs

Under the trend of building information and residential industrialization,prefabricated stairs have been widely used in housing construction in recent years due to the advantages of modular production and high molding quality.As a means of escape when an earthquake occurs,the extent of the damage stair safety plays a crucial impact on the protection of personnel.Based on the prefabricated stairwell unit and combined with the design idea of "placement" in traditional cast-in-situ stairs,this paper proposes a slidable prefabricated stairwell structure.The staircase adopts the structural measures of laying "PTFE " at both ends of the upper and lower ladder sections to form a slidable connection node.While ensuring the advantages of prefabricated components,it eliminates the "K" diagonal bracing effect that appears in traditional stairs as much as possible,improves the shear slip damage of the stairs,and achieves the goal of almost not affecting the overall rigidity of the structure by the stairs.In order to further understand the excellent seismic performance of the slidable prefabricated stair structure system,the seismic simulation shaking table test and finite element comparative analysis of this type of stairwell were carried out for the first time.The main contents are as follows:(1)According to the approximate dimensional analysis method,the existing prototype structure of prefabricated stairs is scaled down.In addition,slidable connection nodes are set at both ends of the ladder slabs.Through shaking table simulation tests,the seismic response,dynamic characteristics and failure characteristics of the scale specimens under different levels of earthquakes are analyzed,and the two slabs of the ladder are observed in the test.The relative slip and deformation of the ends verify the feasibility of slidable connection nodes to improve the seismic performance of stairs.(2)In the ABAQUS finite element analysis software,select appropriate element types,constitutive relations and analysis methods,and establish a correct numerical model to perform nonlinear analysis of slidable prefabricated stairs.The structural dynamic characteristics,acceleration time history curve,crack development and final failure characteristics in the calculation results are comprehensively compared with the test results to verify the correctness of the test results and the reliability of the calculation modeling analysis.(3)On the basis of the verification of the test model,the connection form of the model riser slab and the platform was changed by using ABAQUS software.Then,different types of stairwell models and corresponding multi-story stairwell frame structures are established to study the effects of slidable connection nodes and the impact on the seismic performance of the overall frame structure.The test results and analysis show that the slidable prefabricated stairs can maintain superior seismic performance under large earthquakes,and the stairs are not destroyed before the structure;The finite element analysis software ABAQUS simulated the dynamic characteristics and the time history response test results in good agreement,and the crack development and failure characteristics are consistent with the test phenomena.In the comparison of numerical models,the ductility of the stairs with slidable connection nodes has increased,and the ends of the slabs of the stairs can effectively dissipate energy.When the plastic hinge is formed,the shear deformation of the upper and lower longitudinal ribs in the middle of the span is relatively rich,the crack extension is less,the torsional stiffness of the whole structure is reduced,and it shows good deformation ability.