Study On Simplified Elastic Calculation Method Of Two-way Concrete Composite Slab With Precast Ribbed Panels

Two-way concrete composite slab with precast ribbed panels is a new type of monolithic concrete two-way reinforced floor slab,which is called two-way composite slab for short.At present,the current standard design drawings do not take into account the two-way force effect of the two-way composite slab,and design it according to one-way slab,resulting in too much reinforcement in the strong direction and unreasonable reinforcement in the weak direction.In this paper,based on the theory of anisotropic plate and considering the two-way stress effect of the two-way composite slab,the elastic calculation method of the two-way composite slab is studied.A simplified elastic calculation method is obtained by studying the equivalent relationship between the two-way composite slab and isotropic plate,and the main contents are as follows:(1)The basic differential equation of the flexural surface of the two-way composite slab under uniformly distributed load is solved,according the theory of anisotropic plate.And,elastic calculation methods of common boundary conditions two-way composite slabs are obtained.(2)Elastic calculation coefficients of common boundary conditions two-way composite slabs with stiffness ratios of 0.5,2.0 and span ratios range from 0.5 ~ 1.0 under uniformly distributed load are obtained by programming.What is more,elastic calculation coefficients of one example of two-way composite slab with stiffness ratio is 2.0 and four edges clamped under uniformly distributed load are calculated.(3)Through the formal transformation of the analytical solution of the two-way composite slab and the comparison with the analytical solution of the isotropic plate,the corresponding relation of the elastic calculation coefficients of the bidirectional laminated plate and the isotropic plate is obtained.(4)Based on the basic differential equation of the flexural surface of the two-way composite slab,equivalent relations of the two-way composite slab and isotropic plate are studied.The relationships of deflection and internal forces of two-way composite slab and the equivalent isotropic plates at corresponding points are obtained.(5)Elastic calculation coefficients of two-way composite slabs with stiffness ratios of 0.5,2.0,equivalent span ratios range from 0.5 ~ 1.0 and various boundary conditions under uniformly distributed load are obtained by programming.When the equivalent span ratios are equal,though Span ratios and stiffness ratios are different,elastic calculation coefficients of two-way composite slabs with the same boundary conditions are equal.What is more,when equivalent span ratios are equal to that of isotropic plates,elastic calculation coefficients of two-way composite slabs and isotropic plates are equal.(6)In this paper,a simplified elastic calculation method of two-way composite slab is presented,that is,the elastic calculation process of two-way composite slab can be simplified by using linear interpolation method to check the elastic calculation coefficient table of isotropic plate according to the equivalent span ratio.(7)The simplified elastic calculation method of two-way composite slab is used for one example,which simplifies the elastic calculation process of deflection and bending moments of each zone plate of the case.It is fount that the practicability of this method is well verified.(8)This method is suitable for the second stage internal force analysis of the two-way composite slab,not for the first stage internal force analysis.