RESEARCH ON SHEAR AND BENDING PROPERTIES OF COMPOSITE REINFORCED CONCRETE SLABS WITH REINFORCED TRUSSES

To study the shear and bending properties of the composite reinforced concrete slabs with reinforcement trusses under concentrated forces of small shear-span ratios, shear and bending tests on one composite reinforced concrete double-layer slab with three reinforcement trusses and one composite reinforced concrete slabs with four reinforcement trusses under two concentrated forces of shear-span ratio of 2.3 were conducted. The shear and bending failure phenomenon and mode, the relationship between bending moments and loading point deflection, the characteristic values of bending moments and mechanics model of cross-sections of composite reinforced concrete slabs under shear and bending moments were obtained. According to the shear strength of interface concrete of composite slabs, the formulas of shear and flexural capacity of composite slabs were deduced. The results showed that the failure mode of composite reinforced concrete slabs under concentrated loads of small shear-span ratio was up to the quantities of steel bar trusses in the interface of composite slabs, setting modes and setting positions. The ultimate shear or flexural capacity and the largest deflection of the composite reinforced concrete slab with four reinforced trusses respectively increased by 20.0% and decreased by 20.7% compared with that with three reinforced trusses, that was, the slab with four trusses was of better shear and flexural performance. The formula of ultimate shear and flexural capacity of composite reinforced concrete slabs were deduced based on the shear failure condition of composite slab interfaces, the calculated values were in good agreement with the test values.