Prestressed Concrete Hollow Slab Tension Controls The Reasonable Value Of The Stress

The spiral-rib steel wire has many merits such as high strength, good ductility, credible felting and anchoring capability with concrete and so on. The pre-stressed concrete slab with this sort of steel wire has good mechanical property. So it is an ideal substitute to the cold-processed wire traditionally adopted in pre-stressed concrete slabs.Based on the nonlinear analysis theory of the reinforced concrete flexural member, the numerical analysis program explored by Qiao Yaoke is used to calculate the 171 pre-stressed and hollow-core concrete slabs with spiral-ribs steel wires. The different parameters such as the span depth ratio, the ratio of reinforcement, the strength of steel rib are analyzed by the numerical analysis program. The results indicate that the span depth ratio, the stretching controlling stress, the ratio of reinforcement, the strength of concrete and the strength of steel rib are the primary influencing factors to mechanical property and the failure pattern of the slab. In addition to the relationships between the ratio of deflection to span fu/LO with the slab being failure, the ratio of deflection to span fk/LO under standard load, the ratio of the cracking moment to the design moment Mcr/Md, the span depth ratio, the stretching controlling stress, the ratio of reinforcement, the strength of concrete and the strength of steel rib submit to linear curves. Furthermore, using the regress analysis method, the regress equation of the ratio of deflection to span fu/LO with slab being failure, the ratio of deflection to span fk/LO and ratio of the above fire parameters are resulted.Taking the ratio of deflection to span fu/L0 >1/50 with the slab being failure, the ratio of deflection to span fk/L0 < 1/400 under standard load, the ratio of the cracking moment and the design moment Mcr/Md>0.65 as the determinant term. We can get the reasonable stretching controlling stress of usual span under the different span depth ratio, the different strength of concrete,the different strength of steel rib and the different ratio of reinforcement while satisfying the three factors above.