Analyze The Parameter Influence Of Cast-in-situ Unbonded Prestressed Concrete Hollow Floor Of Cellular Voided And The Design Method

In recent years,ordinary solid floor and hollow floor can not meet the requirements of the larger span and crack resistance performance of the building.The prestressed concrete hollow floor of cellular voided is combined with the technology of prestressed concrete and hollow floor,which is suitable for the building with larger span.At the same time,the honeycomb core model avoids the existence of the difference between the two directions of the tube filler.At present,the researches on these two floors are in the normal use stage.There deign are base on elastic theory method,resulting in excessive security reserve and the decrease of economic performance.So,for more rational use of prestressed hollow floor,it's necessary for us to study it further.To ensure the validity and reliability of the simulation result,this article base on existing test first,and use ABAQUS to simulation a concrete hollow slab of cellular voided and an unbonded prestressed one-way hollow slab with the method of post tensioned.Through changing the bonding way of prestressed steel,reinforcement ratio of non-presstressed steel bars,rib spacing,rib width,the span-depth ratio and the thickness of bottom slab and top slab,we study what the impact they have on the force performance and deformation property.The finite element results shows,the bearing capacity of bonded prestressing slab is higher than non-bonded prestressing slab's.When designing the best method of changing the reinforcement ratio of non prestressed reinforcement is to change the diameter of steel bar.The best reinforcement ratio is 0.60%?0.7%.The rib spacing should not be more than 1000mm,and the the best is 500mm?800mm.The width of rib is 60mm?80mm.The span-depth ratio is about 40?42.If the building has a higher demand for cracking performance,the thickness of top slab is not greater than the bottom slab.The difference between the thickness of top slab and the bottom slab should not be more than 30mm.For the convenient of construction and design,the top slab and bottom slab to the same thickness,and the thickness is best to 60mm?80mm.The second,for the commonly used of two-way board,we take a prestressed hollow floor which sizes is 15mx 15m as an example.According to the existing ordinary solid two-way slab analysis theory,we use standard method and the revised yield-line theory to calculate the internal force and ultimate bearing capacity and check the deflection under the serviceability limit state by using I-shaped section and rectangle section.Meanwhile,the ABAQUS finite element software is used to verify the simulation.The results show that when the slab is designed,the internal force calculated by the revised yield-line theory method is more close to the finite element results.The strip with unit width is best to equivalent I-shaped cross section.For the calculation of ultimate bearing capacity,the rectangle section is best for using the standard elastic method,and the I-shaped section is best for using the revised yield-line theory method.When calculating the deflection of the slab in elastic state,the section should be equivalent to rectangular section by using two-way slab empirical coefficient method.