# D13.A.5 Two Dimensional Elements (slabs, walls, shells)

In general case calculation of reinforcement for 2D members is carried out two times – according to conditions of strength and conditions of limiting opened width of cracks. If reinforcement is calculated according to conditions of strength, design values of loads have to be used, and for conditions of limiting crack width – characteristic (normative) loads are employed. Both calculations can be made in one session taking advantage of multiple analysis possibility of the program STAAD.Pro.

Symmetric or nonsymmetrical reinforcement of 2D members is calculated according to conditions of strength or according to conditions of limiting opened crack width (see for example STA).

In reinforcement calculation for 2D members it is necessary to pay attention to arrangement of local axes of member and direction of reinforcement (see for example CL and CRA).

An example of output of calculation results is presented bellow.

 SLAB/WALL DESIGN RESULTS (by stresses in local axes for limitation of crack width) Element Asx sq.cm/m Mx kNm/m Nx kN/m Load.N. (X) Asy sq.cm/m My kNm/m Ny kN/m Load N. (Y) 60 TOP 0.00 - 4.9 0.00 1 0.00 - 4.5 0.00 1 BOT 3.53 - 9.9 0.00 3 3.46 - 8.9 0.00 3 61 TOP 0.00 - 5.3 0.00 1 0.00 - 4.7 0.00 1 BOT 3.87 - 10.7 0.00 3 3.65 - 9.4 0.00 3 62 TOP 0.00 - 5.6 0.00 1 0.00 - 4.8 0.00 1 BOT 4.10 - 11.2 0.00 3 3.77 - 9.6 0.00 3

Here:

Table 1. Slab design output
Result Description
Element number of finite element, TOP  - top zone of member, BOT - bottom zone of member (top zone of member is determined by positive direction of local axis   -see Fig.2)
Asx intensity of reinforcing in the first direction (parallel to the local axis  ), sq.cm/m
Mx distributed bending moment in respect to the local axis   , kNm/m
Nx distributed longitudinal force directed parallel to the axis , kNm/m