Experimental Tests on Parameters Influencing on Shear - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 64

Fig. 4.8 Load-deflection
responses on middle span

4.4.3.2 Crack Patterns and Load-Crack Width Responses

The crack pattern evolution on shear span at different loads is shown in Fig. 4.9 as a
selection of the main types of beams with the same geometry. The crack widths
were measured by means of video recording and image analysis. Figure 4.10 gives
the load-crack width response of the beams. These

gures make it possible to

analyze the in fl uence of the type of reinforcement: transverse, stirrups (TR) or bers

or both. The other variables analyzed did not signi cantly affect this behavior. As

can be seen in Fig. 4.9 , HF600TR/2 achieved the highest ultimate load and its

rst
visible crack appeared at a higher load than the other beams. Comparing H600TR/3
(stirrups only) with HF600/4 ( bers only), Fig. 4.9 clearly shows that stirrups

reduce the number of cracks but they are wider than those in HF600/4. The ber-

only beams (HF600/4) showed thinner cracks that were closer together.
The average crack inclination was very close to 22

° for all the beams.

Fig. 4.9 Cracking patterns. Crack appearance and its corresponding load level