Issue 57

K. Benyahi et alii, Frattura ed Integrità Strutturale, 57 (2021) 195-222; DOI: 10.3221/IGF-ESIS.57.16

Before concrete cracking:

   1 ft





:

= E .

(19)

b1

b0 1

To describe the decreasing branch, after cracking, which reflects the influence of the concrete loaded between the cracks on the average strain, we adopt the relation proposed by Belarbi and Hsu [46]:

0,4

         ft 1 f

(20)

 b

1 t

f E

where:

t





ft

b

0

The behaviors of reinforcement and the prestressing reinforcement are characterized by the types of relations admitted by the rules BAEL99 [43] and BPEL99 [44]: - Longitudinal reinforcement

  ax

( ). a x x E  

(21)

- Transverse reinforcement

  ay

( ). y E   at y

(22)

- Prestressing reinforcement

  px

( ). ap x x E  

(23)

The shear stresses are then deduced from the equilibrium of the layers between the design section under the loading state (N, M, V) and the neighboring section subjected to the forces ( 1 N , 1 M , 1 V ) which are expressed by:

    N N M M V d V V 1 1 .

(24)

1

The two sections are analyzed so as to satisfy in each of them the equilibrium equations. By applying the classical RDM method, we study the equilibrium of all the forces acting on a layer of order k shown in the figure (Fig. 6):

Figure 6: Forces acting on a concrete layer between two sections.

202