Study On Behavior Of Cast-in-place Reinforced Concrete Hollow Slab Connected With Shear Wall

In order to study the seismic behavior of cast-in-place reinforced concrete hollow slab connected with shear wall, according to the principle of "strong joint and weak member", five full-scale cast-in-place reinforced concrete hollow slab- shear wall joint specimens with different reinforcement details have been tested under reversed cyclic loading. The five specimens have the same dimensions and the same concrete strength. The main variables of the specimens are existence of stirrups and prestress tendons in the edge ribs of the hollow slab and different layouts of the prestress tendons. Three specimens are designed in hollow slab shear failure while the other two are designed in hollow slab flexural failure.From the experimental results it is found that the real failure modes of the five specimens are the same as the designed failure modes. The measured yield loads of the 5 specimens are close to the predicted values. Measured reinforcement strain distributions at the different levels reveal that the cross section of the hollow slab fulfills the assumption of the plan section remaining plan before the yielding load. The average nominal flexural rigidity of the specimens before their concrete cracking is about 92% of the theoretical elastic flexural rigidity. When the load is about half of the yielding load, the average nominal flexural rigidity of the specimens is about 48% (non prestressed) or 79% (prestressed) of the theoretical elastic flexural rigidity. The nominal flexural rigidity increases about 65% when the floor prestressed. The flexural rigidity of the specimens at yielding load is about 21% of the theoretical elastic flexural rigidity. Arranging stirrups or prestress tendons in the edge ribs can increase the shear resisting capacity of the hollow slab. The ultimate shear displacement angles of all specimens are greater than 1/40. The ultimate shear displacement angles of the flexural failure specimens are greater than 1/25. The displacement ductility ratio of all specimens is greater than 4. Hysteretic energy dissipation of the specimens is stable and the specimen J5 which simulated real reinforcement layout has the best hysteretic energy dissipation ratio. More else, non-linear finite element analyses of the 5 specimens using MSC.MARC have been carried out. The simulated results agree with the experimental results. The calculation results show that the predicted failure modes of the specimens are close to the experimental failure modes and the load-displacement curves are similar to the measured curves before their yielding load. Flexural-shear cracks are found on all middle ribs. The shear resisting capacity of the hollow slabs with different thickness and different width can be calculated with the formula of the code for design of concrete structures. In this paper the shear resisting capacity of six kinds of normal size hollow slabs under vertical load effect combinations has been calculated. Based on the calculated shear resisting capacity, the maximum allowable live load for the different span hollow slabs under the shear resisting capacity control is predicted. These results can be referenced during design of the hollow slab.The results showed that cast-in-place prestress reinforced concrete hollow slab connected with shear wall can meet the seismic design requirements according to the design method proposed in this paper.