Evaluation and Repair of Wrought Iron and - Purdue e-Pubs ...

26From all the surveys that were distributed 59 were received. Of the surveys sentout to the DOTs 35 were received, and 2 were received from other state’s LTAPs. Atotal of 19 surveys were received from the local county engineers of Indiana, and 3 moresurveys were received from various bridge engineering consultants. An example of thesurvey that was completed and distributed can be seen Appendix B.Of the 59 received state DOT completed surveys, 16 reported that there werehistoric wrought iron bridges in their state. Of these 16 states, 1 state had over 101bridges, 1 state had between 41 and 100 bridges, 2 had between 21 and 40 bridges, 2 hadbetween 11 and 20 bridges, and 10 had between 1 and 10 bridges. A plot showing thedistribution of historic bridges is shown in Figure 2.16. Of all the state DOTs thatreported that there were historic wrought iron bridges in their state, 7 states reported thatthey maintained a number of the bridges.From all received surveys completed by the state DOTs none reported that therewere formal repair and maintenance procedures established for historic wrought ironbridges. Five of the DOTs surveyed said they allowed heat straightening in these types ofbridges and three allowed welding. The inspection procedures reported for most historicbridges included only visual inspection, except for two states that also included dyepenetrantand ultrasonic testing to detect suspect cracking.For load rating, the majority of the states reported that they used the proceduresoutlined in the AASHTO Manual for the Condition Evaluation of Bridges (1994). FiveDOTs specifically reported that they either determined the actual material properties ofthe wrought iron bridge material or used predetermined material properties of wroughtiron from literature in evaluating the load capacity of the bridges. Two DOTs stated theyused the same material properties as steel to evaluate the load capacity of the historicwrought iron bridges.