Nonlinear Finite Element Analysis Of Reinforced Concrete Waffle

As an important force-resistance structure, the capacity of the reinforced concrete waffle slab is better than one-way slab and two-way slab: not only on the capacity of force-resistance and economic, but also on the capacity of externality. But interior force of reinforced concrete waffle slab is very difficult to be calculated, that because the distribution of interior force is complex under different loads, boundary condition and section types. Moreover, the mutual action of moment and torsion will make the problem more difficult. At present the calculation of waffle focus on elastic state, and the designer usually consult form on reference books. The deflection of plastic phase is the 2~3 times of that of elastic phase. The interior force and deflection calculated is far off the actual result. That is, some place will crack for lack of steel bars while in other place steel bars are too enough to yield. Therefore in this paper, finite element program for waffle is designed. At the same time, it considers the nonlinear of steer and concrete.The paper roundly introduce the method of analyze the structure, including elastic analysis method, the plastic method considering the interior force redistributing and plastic limit analysis method. Moreover, the three kinds of methods are compared in this paper. The analysis program which is concerning reinforced concrete rectangle section beam on the pure moment is designed. And the program considers the nonlinear capacity of the steel and concrete. It elicit the rule of bending stiffness of reinforced concrete rectangle section beam along with the gradually increscent load. The reinforced concrete waffle analysis program which adopts the three-dimensional beam element is also designed. It introduces increment- iterative method and intercalates the convergence condition in order to assuring calculate precision. It adopts the program to analyze two kinds waffle structure. Moreover the result of program and other software is compared. The comparing result is satisfactory.