The use of timber–concrete composite (TCC) bridges in the United States dates back to approximately 1924 when the first bridge was constructed. Since then a large number of bridges have been built, of which more than 1,400 remain in service. The oldest bridges still in service are now more than 84 years old and predominately consist of two different TCC systems. The first system is a slab-type system that includes a longitudinal nail-laminated deck composite with a concrete deck top layer. The second system is a stringer system that includes either sawn timber or glulam stringers supporting a concrete deck top layer. The records indicate that most of the TCC highway bridges were constructed during the period of 1930–1960. The study presented in this paper discusses the experience and per-formance of these bridge systems in the US. The analysis is based on a review of the relevant literature and databases complemented with field inspections conducted within various research projects. Along with this review, a historical overview of the codes and guidelines available for the design of TCC bridges in the US is also included. The analysis undertaken showed that TCC bridges are an effective and durable design alternative for highway bridges once they have shown a high performance level, in some situations after more than 80 years in service with a low maintenance level.
The field of Civil Engineering has lately gained increasing interest in Unmanned Aerial Vehicles (UAV), commonly referred to as drones. Due to an increase of deteriorating bridges according to the report released by the American Society of Civil Engineers (ASCE), a more efficient and cost-effective alternative for bridge inspection is required. The goal of this paper was to analyze the effectiveness of drones as supplemental bridge inspection tools. In pursuit of this goal, the selected bridge for inspection was a three-span gluedlaminated timber girder with a composite concrete deck located near the city of Keystone in the state of South Dakota (SD)...
Project contact is Junwon Seo at South Dakota State University
Cross-Laminated Timber (CLT) has great potential to promote wood products markets in appropriate transportation structures, particularly bridges on low-volume roads such as rural or forest roads. The project’s goals are to perform field load testing and evaluation of a demonstration CLT bridge on the nation’s low-volume roads and evaluate its long-term performance under in-service loads and environmental exposure. The team will pursue these goals through the following research objectives: 1) Design the demonstration CLT bridge system with design details; 2) Fabricate the designed CLT bridge; 3) Install the fabricated CLT bridge on a roadway in Grand Portage National Monument with Western Wood Structures, Wheeler, Cook County in Minnesota and the National Park Service; and 4) Perform load testing to assess performance of the implemented bridge and monitor its moisture content and field performance through visual inspection for its long-term behavior evaluation.
This research aims to develop a new bridge inspection approach using unmanned aerial vehicle (UAV) coupled with digital image correlation (DIC) system. The DIC system incorporating UAV images can measure displacements or strains by analyzing patterns of reference and deformed images. As part of this research, a commercially available UAV, DJI Matrice 210, was integrated with the DIC system using a 3D printed mounting plate, and the joint UAV-DIC system was utilized to inspect a timber bridge girder in the Structure Lab. Then, the UAV-DIC system inspected an existing timber slab bridge in Pipestone, Minnesota, but the system was not able to efficiently identify critical damage due to its instability caused by windy conditions. Therefore, only the UAV equipped with a gimbal camera was operated to perform the bridge inspection. A significant number of images from the UAV were used and analyzed through a conventional image analysis algorithm within ImageJ software for damage quantification. The major conclusion from this research was that the UAV-DIC system was only able to detect and quantify damage (i.e., crack) on the considered girder under almost zero ambient wind conditions, and the UAV integrated with the image analysis algorithm was capable of damage identification and quantification for the inspected bridge.