21.2.3 Aggregate Interlock Relation (Walraven & Reinhardt)

Walraven & Reinhardt [111] have deduced linear relations which fit their experiments [112] on lightweight and gravel concrete. We only consider the relations restricted to gravel concrete because the main subject of this section is the analysis of crack dilatancy models for gravel concrete. Figure 21.10

Figure 21.10: Aggregate interlock relation (Walraven & Reinhardt)

shows the response diagram for this model. The relations which fit the results with the greatest accuracy are

$$\begin{split}f_{t} &= \frac{ -f_{\mathrm{cc}} }{30} + \left( ... ... 0.15 \right) f_{\mathrm{cc}} \right) \,\mathrm{d}t \end{split}$$ (21.18)

in which  dt $\geq$ 0 , f_t $\geq$ 0 and f_n $\leq$ 0 . For the tangential stiffness coefficients see Feenstra [26].