3.2. Test procedure
Loading and observation arrangements are shown in Fig. 3.
All the beams were tested to failure under two-point symmetric
top loading using a 3 MN capacity universal testing machine. At
the location of loading and support points, a 100 mm wide steel
plate was provided to prevent premature crushing or bearing
failure. One side of both supports is a hinge, and the other side
is a roller to allow horizontal movement. Vertical de ections at
mid-span were monitored by the LVDTs. At each loading stage,
the test data were captured by a data logger and automatically
stored.
Both side surfaces of the beam were painted in a white color
with the objective of the observation of crack development
during testing. The load was kept constant while cracks were
marked and photographed. The inclined crack width of concrete
struts joining load points or supports, and corners of the
opening was monitored by the PI type gages as shown in Fig. 3.
4. Test results and discussions