Integral abutment bridges are very common for short span bridges in the United State due to their less construction and maintenance cost and generally good performance. This thesis studies the first integral abutment bridge using Folded Plate Girder (FPG) Bridge System. The bridge is instrumented with a variety of gauges to capture the behavior of the bridge, and a total of two year and one month [11/2011~12/2013] of data are collected and long-term data monitoring is performed. Live load test and long term temperature effect on the bridge are studied using finite element modeling and compared with actual field data. Girder strain/stress at mid-span and quarter-span and abutment rotations were investigated. From the result, first the bridge was found to show good performance. Shear lag effect was found to be happening at the bottom flange-to-web junction of the steel girder when subjected to concentrated loading. Thermal gradient was found to be significant on the girder strain and abutment rotations.