Study On The Performance Of Precast Reinforced Hollow Concrete Slab Strengthened With Slotting And Superposion

Many precast concrete hollow slab due to prolonged use of the process is lack ofnecessary repairs and maintenance, which may cause damage or even destroy. Besides,the usage changes of some of the hollow slabs may cause the short of capacity. Butconsider of the historical value of the building, location and so forth, these buildingscannot be removed. If the mechanical properties of the original members cannot meetthe requirements, it is a potential threat to the reliability of the building, so we need toreinforce the building to ensure the functional requirements of the new building. Whilemany precast concrete hollow slabs of the existing building cannot satisfy therequirement of usage, and the way we use to reinforce the slab for now cannot takeadvantage of the prior slab sufficiently, which causes a lot of waste. In this paper, weprovide a more reliable and economical way, named“The method of digging hole andincreasing thickness”, means we drill holes of the precast concrete hollow slab first, andthen put in the steel bars and cast concrete at an exact level. It is the first time we putforward this method, which can improve the anti-shear ability of combined interfaceobviously.We made eleven samples to test the bearing capacity, crack resistance and stiffnessof normal section of reinforced concrete under static loading. We analyzed the variationof strain of the reinforced concrete and recorded the destruction of superimposedsurfaces. After that, we model the mechanical behavior and stress distribution ofdifferent kinds of concrete slab with Abaqus. Finally, based on the theoretical analysisand practical experiment, we give a calculation method and analysis method ofanti-shear ability of combined interface and the normal section capacity of membersunder secondary force.The result we get from the practical experiment matches with our theory well: Theanti-shear ability of combined interface was improved apparently, which makes thewhole member works very well. And the normal section bearing capacity, crackresistance and stiffness were also get improved, the calculation method of normalsection flexural capacity, the maximum crack width, deflection of member under bear inthe “Code for design of concrete structures”(GB50010-2010) are fully applicable to this“digging hole and increasing thickness” method. The reinforced member can becalculated as its full size. When calculating cracking moment, the formula-section andcross-section resistance moment resistance of plastic should be amended by the factor inthe code.