The Numerical Simulation And Theory Study On Orthotropic Waffle Slab

As an important force-resistance structure, the capacity of reinforced concrete waffle slab is better than one-way slab and two-way slab. Not only does waffle slab exhibit higher rigidity, smaller deflection and behave well under vertical loads, but also the structure made by waffle slab has the excellence of lower structural height, lightweight and economic benefits and so on. So they are best suited for large span structures as well as tall building. There still have been few experimental and theoretical investigations on these structures up to now, especially on that of supporting along four edges. And research is too long and its cost is too high, which is not economical. In this thesis, the theory analysis and numerical calculation of stress and deformation of the reinforced concrete waffle slab under vertical loads by numerical simulation of computer has conducted. It shows that the above method is one of the important approach to settle the problem of modern engineering technology and theoretical analysis. Main achievements that have been done in this thesis as fellows:1. Finite element analysis program ANSYS and TRUEGRID is used for nonlinear analysis for waffle slabs under short-term concentrated load, and the simulation results are compared with the experimental results, which is presented that finite element model is verified, and the state of force and properties of reinforced concrete waffle slab are well simulated.2. Slabs are analyzed under concentrated load and uniformly distributed loads, there are some similarities about behaviors between waffle slabs and solid slabs, that is to say, the line of plastic hinge spread along four corners, and it distribute in the angle of 45, but the properties of the former are better than the latter.3. The properties of force are compared between three solid slabs and one waffle slab, which have the same material dosage, flexural rigidity, or thickness. Affection of the number of bays and supporting breadth on limiting load and the differences between ribs and general beam are researched.4. All kinds of elastic methods of waffle slab are summed up. Based on classical elastic theory, in this paper waffle slab is converted to orthotropic solid plates by the pseudo-plate method and equilibrium equation of moment is built.5. The ultimate load of the waffle slab can be obtained by ultimate equilibrium method. Considering the affection of concrete nonlinear deformation, crack, reinforce plastic deformation and so on, waffle slab is equally as solid slab, the properties of waffle slab is compared with those of solid slab and general beam, from which we know that the deformation of waffle slab accords with that of solid slab. The deformation of the waffle slab can be calculated by using the tables of two-way solid slab with a rigidity lowering coefficient, which is very close to the test value in the uncracked and cracked stages. The depth-span ratio is analyzed, which provides references for the design of waffle slab.