DATA ACQUISITION
The data acquisition system and the strain readout box were both housed in a 23 ft. motor home which was parked adjacent to each bridge. Individual cables were run from each strain gage, accelerometer and LVDT to a control panel in the motor home. The control panel was connected to the data acquisition system. The data acquisition
system is a MEGADAC system made by OPTIM ELECTRONICS INC.. The system is capable of collecting data at a low sampling rate (static test) and a high sampling rate (dynamic test). The maximum sampling rate of the system is about 250,000 samples per second, depending on the number of channels used.
DESCRIPTIONS OF BRIDGES AND PRESENTATION OF RESULTS
The two test bridges will be referred to as Bridge A and Bridge B, in the following discussion. The test results of each bridge will be presented and discussed separately.
BRIDGE A: 1-75 OVER CALOOSAHATCHE RIVER
Bridge A is located on F-75 across Caloosahatche River near Fort Myers, Florida. The bridge consists of six 45.5 ft continuous spans and was designed to carry two lanes of HS20 loading. Each span has five AASHTO type II girders spaced at 9'-3". The first three spans were instrumented.
Static Test of Span A3
The static load test was performed on span 3. Figure 4 shows the load position of the testing vehicles during all static tests. Figure 5(a) shows the increase in the measured midspan strains at different stages of loading during the static test. Figure 5(b) shows the relationship between the applied load and the measured strain for girders is linear, and elastic. Neither cracking nor other signs of distress were observed at the maximum applied loads.