Studies On Plane Stiffness And Bearing Capacity Of Composite Structure For Slab On The Lower Flange

This paper researches the plane stiffness of new composite structure for slab on the lower flange, which is compared with the traditional structure for the slab on the top flange. Test is done on the condition of vertical load and level load are given. Test result suggests , in the serviceability limit states, displacement is littleer, the plane stiffness infinite assumption may be established. In the elastic term, the two load-displacement curves slope are similar, the new structure s slope is more greatly. Stiffness is better than the traditional structure. But the new joint s crack load is littleer. Strengthen step should be taken to improve the crack load. New joint s failing load is littleer, but the traditional joint is completely brirtleness damage, consume energy term almost does not exist, not benefit for anti-seismic capability. The new joint has a little plate or a descent length, It s consume energy capability is better than the traditional joint, anti-seismic capability is better. Intensity and stiffness are obviously strengthened, ducticity raises greatly. It is a good anti-seismic structure. On the fact of the conclusion, the appearance in the process of test and the specialized theory .base, the paper proposes a new kind of composite node.Elastic theory and plastic theory are adopted in the analysis of the two section composite beam. Elastic theory suggests, on the condition of the same steel beam section size, the composite beam for the floorslab is suited lower flanges convertion section stiffness cuts down by 75.1%,elastic limit bending resistant capability cuts down by 47.9%, than the composite beam for the floorslab is suited on the top flange. It s conversion section stiffness is lifted 8.0%,elastic limit bending resistant capability is lifted 0.20%, than the steel beam. Plastic theory suggests, the composite beam for the floorslab is suited lower flange, it s plastic limit moment cuts down by 52.4% than the composite beam for the floorslab is suited on the top flange. It s plastic limit moment lifts 8.8% than the steel beam, which is on the same condition.