3rd international conference on timber bridges 2017
The use of timber–concrete composite (TCC) bridges in the United States dates back to circa 1925. Two different TCC systems were constructed during this early period. The first system included a longitudinal nail-laminated deck composite with a concrete deck top layer. The second system included sawn timber stringers supporting a concrete deck top layer. Records indicate that most of the TCC highway bridges were constructed between 1930 and 1960. The current U.S. National Bridge Inventory (NBI) database indicates that there may be well over 1,000 of this bridge type still in service. This paper will review and discuss the current conditions of several TCC bridges that remain in service today. This will be based on the information given in the NBI and other relevant documents, complemented with information provided by 25 field inspections undertaken during June 2016 in the Pacific Northwest states of Oregon and Washington.