njit-etd2003-032 - New Jersey Institute of Technology

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concrete surface. The load continued to increase and vertical flexural cracks began to
form at about 31.8 kips, and it was followed by the small inclined flexure-shear
cracks. Obviously, the load increase became much slower, and flexural cracks
became wider. That meant that the flexural reinforcement started to take over the
load. From the load-deflection curve, it can be observed that during this period the
deflection increased about 1.2 inches, while the load only increased about 5 kips. At
about 33.6 kips, the full shear cracks developed followed by the delamination along
the 2 nd and 3 rd CFRP strips from the supports.
The test stopped when the load
dropped to 2.4 kips (Figure 2.14).
Figure 2.14 Failure of Beam Z4-45.
d.) Beam Z4-Mid
The fourth beam was Z4-Mid (Figure 2.5). The load dropped from 6.6 kips to 2.9 kips
shortl y after the test started due to the local concrete crush at one of the support. After
that, the load-deflection curve remained linear until the load reached 27.8 kips. The
beam failed in shear at the load of 27.8 kips and at the same time one end of the