Study On The Mechanism And Seismic Performance Of High Rise And Large Span Cast In Situ Hollow Floor

The large span cast in situ concrete hollow floor is a new type of structural system,which is a kind of floor slab structure.Due to the adoption of wide flat beam members,the structure can effectively reduce the storey height and increase the use area.At the same time,hollow floor also has a good mechanical performance,such as reducing weight,reducing seismic action,and it is a kind of structural form which combines the mechanical properties and the use function.At present,the domestic and foreign research on this structural system mainly concentrated bending and shearing test and theoretical research on mechanical properties of the single piece of hollow floor,seismic research and for considering the wide flat beam constraint effect on multi slab overall study on mechanical properties and application of large span hollow slab in high-rise buildings is relatively small.In this paper,through the field test and numerical simulation,the vertical bearing mechanism and seismic performance of long span hollow floor are studied:(1)The results of field tests show that the vertical loading,large span hollow slab beam flat bandwidth can meet the requirement of the current standard of floor serviceability limit state of deflection.At the same time,due to the wide flat beam height is not enough,can not achieve the effective restraint of the hollow plate,making the 2 plates of the vertical deformation curve presents the characteristics of single plate.(2)Based on the hollow layered shell element for large span hollow slab,finite element analysis results show that the increase of beam height can effectively improve the constraint on wide flat beam on the surrounding hollow floor,and according to the characteristics of section shape and stress distribution of the hollow plate,put forward the calculation method of the crack tube core type hollow slab,the calculation results agree well with the experimental results.(3)Response spectrum analysis results show that the wide flat beam hollow floor structure due to height than the ordinary ribbed floor structure of lo w layer,high stiffness,small elastic deformation,easier to meet the requirement of deformation;torsional period of wide flat beam hollow floor structure of the larger proportion,proposed to increase the inner cylinder size or method of rigidity of the beam frame side to increase improve the overall structure of the torsional stiffness.125 gal elastoplastic analysis results show that the floor of ordinary reinforced ribbed floor structure with wide flat beam hollow floor structure of the maximum stress value was 8.4MPa and 188.0MPa,the stress of wide flat beam hollow floor reinforcement stress is larger than that of ordinary reinforced ribbed floor slab reinforcement,stress distribution range is greater than the ordinary rib floor,illustrate the role of wide flat beam hollow floor slab reinforcement structure is significantly larger than normal ribbed floor structure.(4)Under the rare earthquake incremental dynamic elastic-plastic time history analysis(IDA)results show that with the increase of se ismic action,wide flat beam hollow floor structure stiffness degradation than ordinary ribbed floor structure,damage,damping increasing,cycle extension,vertex displacement reaction is elastic phase lag significantly,energy dissipation capacity strong.The stress nephogram of the upper surface of the first floor under different earthquake action shows that the damage degree of the wide flat beam hollow floor is deeper than that of the ordinary rib beam floor,the damage range is wider,and the energy dissipation capacity is more favorable than that of the 2.However,due to the lack of stiffness of the wide flat beam,it can not form an effective restraint to the floor,and the mechanical performance of the floor shows the characteristics of the opposite side load between the shear wall and the frame beam.Wide flat beam hollow floor structure shear wall reinforcement stress on each floor floor than ordinary ribbed floor structure is serious,indicates that the structure of the shear wall stress of high performance requirements,should be highly valued,suggestions for the improvement of wide flat beam hollow floor outside shear wall longitudinal reinforcement ratio or with the dark out of plane beam column and ensure performance of the shear wall.