Study On Mechanical Behavior And Engineering Application Of Ribbed Hollow Plate Under Soil Covering

With the rapid development of the national economy,urban rail transit is widely used in first-tier and second-tier cities.In the construction of existing subway stations,the main structure of the station is mainly reinforced concrete solid frame structure,the structure has a large amount of concrete and reinforcing steel,which is of great importance and high cost.The multi-ribbed hollow plate is an optimization of the section of solid plate,whose deadweight and stiffness decrease without affecting the bearing capacity of the structure,which can improve the seismic performance of the structure,reduce the amount of concrete and steel,and reduce the project cost.This paper uses the numerical simulation of finite element software ANSYS,assuming that the multi-ribbed hollow slab is applied to the main frame structure of the station,the variation law of internal forces of different hollow slab is analyzed.Follows are the main research contents and conclusions:(1)The two-dimensional plane model of the station roof frame with solid roof and hollow roof is established through numerical simulation.The comparative analysis shows that: Before and after replacing the multi-ribbed hollow slab on the top plate of the frame,the internal forces of the side walls,pillars,middle plate and bottom plate have no obvious change,only the internal force of the top plate changes greatly.The bending moments in the middle and middle spans of the side spans decreased more,at most reduced to 13.6%;the bending moments at the side walls and columns were smaller,and the maximum was only 2.7%.The shearing force at each cross section of the roof does not change much,and the maximum reduction is only4.6%.It is found that the shear resistance of hollow roof is weaker than that of solid roof;the crack width of side span and middle span is smaller than that of solid roof;the anti-heaving performance of hollow roof frame is weaker than that of solid roof.(2)By analyzing the two-dimensional plane model of 6 different hollowness roof and upper-middle slab station frames: The maximum bending moment of the tension side and compression side of the top and upper-middle plates decreases with the increase of the hollowness;the shearing safety factor decreases with the increase of the hollow ratio,but when the longitudinal rib spacing is constant,as the hollow ratio increases,the shearing safety factor does not change much,the larger the longitudinal rib spacing,the more favorable the shear resistance;the maximum crack width is at the middle of the side span,which decreases with the increase of the hollowness.After replacing the upper-middle plate with a hollow plate,it has almost no effect on the internal force of the hollow top slab.The bending moment,shear safety factor and crack width of hollow top plate and hollow top plate are basically the same,but the anti-sink and buoyancy performance of hollow top plate decreaseswith the increase of hollow ratio.(3)Through analysis of the three-dimensional model: The maximum vertical displacement of the hollow top slab and the hollow upper-middle slab is at the middle of the mid-span,and the maximum vertical displacements of the solid slab and the solid upper-middle slab are reduced.The maximum first principal stress of the hollow roof slab is at the axillary angle of the side wall,and the maximum first principal stress of the hollow upper-middle slab is around the upper pillar of the slab,but the stress distribution of the hollow top plate and the hollow upper-middle plate is the same.When replacing a solid board with a hollow slab,the first principal stress at each position on the roof slab has increased,and the stress concentration phenomenon is more obvious;the load on the upper-middle plate is small,the hollow part is less affected by stress concentration,the first principal stress at various positions on the slab did not change significantly.