Equilibrium and yield conditions
This chapter examines the load carrying capacity of thin slabs with small deflections. An ideally plastic material behaviour is assumed, without going into detail with respect to deformation demands and deformation capacity. As slabs are generally weakly reinforced, there is usually little cause for concern in this respect. Slabs are the most widespread use of reinforced concrete. They were already dealt with in detail in Stahlbeton II, and further information is given in this chapter. First, the basic static relationships are established from which the yield conditions can be derived.
In practice, numerical methods, in particular the finite element method, are mostly used today to determine the stresses. For plausibility checks, appropriate approximate methods such as the equivalent frame method are suitable.
In plastic slab theory, static and kinematic calculation methods are used to determine the load carrying capacity.
For design, usually only the state of bending of the slab is considered. The influence of the shear forces is usually only critical for concentrated forces and supports (punching).
Shear and punching shear
The subject of this chapter is the influence of shear forces on the behaviour of slabs. This is essentially a repetition from the lecture Stahlbeton II with selective additions.
In engineering practice, finite element analyses are the standard procedure for the dimensioning and verification of slabs. This chapter gives insight into numerical modelling approaches for reinforced concrete slabs, their applicability and limits.