A hydraulic actuator was used to apply the displacement to the beams. The applied

displacement was distributed to the two load points using a steel spreader beam. From the

spreader beam the displacement was transferred to the beam using two steel rollers. The

rollers allowed the loading mechanism to follow the rotation of the beam as the load

increased, whereas steel plates distributed the load to avoid localized failure of the

concrete material that could happen if the load was applied to a very small area or single

point. A load cell was used to measure the applied force. The load points were located

5.5 ft from each support. This created a 3-ft region in the center of the span with pure

flexure.

 The beams were loaded at a rate of 0.004-in. per second. The displacement was

applied monotonically until the beam could no longer sustain a significant load.

Instrumentation

 A series of 15 linear variable differential transducers (LVDTs) were placed at 12-

in. intervals to measure the displacement of the beam at different locations along the

length of the beams (see Fig. 4-7). The LVDTs were labeled from north to south as Dl

through D 15.

 Four tilt meters, two at the supports and two at 3 ft from the supports, were used to

measure the rotation of the beams at those locations (see Fig. 4-7). The tilt meters were

labeled from north to south as T1 through T4.

 Foil strain gages were attached on the sides of the beams at mid-span (Fig. 4-8) and

on top of the beam (Fig. 4-9). The strain gages at the side of the beams were labeled from

the top down as SE1 through SE7 for the east side and SW1 trough SW7 for the west side

of the beam. The two bottom strain gages on the sides of the beams were located

approximately at the same level as the two layers of the steel flexural reinforcement and