Driven Concrete Pile Foundation Monitoring with Embedded Data Collector System
Florida Department of Transportation (FDOT) sponsored research performed at the University of Florida resulted in developing a wireless monitoring and real time static capacity estimate technology for driven piles. This new technology, Embedded Data Collector (EDC), uses two levels of instrumentation, embedded in the body of precast prestressed concrete piles near the head and tip. Strain and acceleration measurements obtained at these instrumentation levels during driving are sent wirelessly to a receiver in the field, and analyzed in real time to provide the operator with estimates of static capacity, stresses in the pile, transfer energy, damping factor, stroke height, and other relevant parameters used to evaluate the pile driving process and the driving system. The EDC system is currently undergoing phase one of a two phase field evaluation program planned by the FDOT to determine the level of reliability that can be anticipated by its use. The first phase consists of monitoring piles with EDC instrumentation and concurrently monitoring them with the Pile Driving Analyzer (PDA), given that there is ample data supporting the reliability of PDA. Measurements of strain and particle acceleration converted to force and velocity traces can then be compared between the two systems, along with the corresponding calculated magnitude of downward and upward traveling stress waves as they move along the pile at any point in time. Selected hammer blows recorded by PDA equipment are analyzed by means of signal matching software (CAPWAP) and the estimated static skin, end bearing, and total resistance obtained are compared against EDC static resistance predictions. The second phase of the evaluation will compare EDC estimates of static capacity against instrumented static load test results. The purpose of this paper, is only to present a summary of results obtained thus far in phase one, and compares EDC estimates of static capacity results with those from PDA and CAPWAP.
Investigation of carbon fiber composite cables (CFCC) in prestressed concrete piles
The Florida Department of Transportation (FDOT) commonly uses prestressed concrete piles in bridge foundations. These piles are prestressed with steel strands that, when installed in aggressive or marine environments, are subject to corrosion and therefore rapid degradation. Many solutions may address this issue, but they are not long-term. Hence, it would be desirable to use advanced materials that do not corrode. The goal of this research was to assess the suitability of using carbon fiber composite cables (CFCC), which do not corrode, in lieu of conventional steel prestressing strands. Five 24-in. square prestressed concrete piles, three 40-ft long and two 100-ft long, were cast using 0.6-in. diameter CFCC strands produced by Tokyo Rope Manufacturing Company. A special anchoring system was used because CFCC strands cannot be conventionally gripped using wedges and a jack. The techniques employed to prestress these strands were documented, as well as the unique aspects involved in constructing and precasting CFCC-prestressed piles. During strand detensioning, stresses were monitored in the concrete at the piles' ends to determine the transfer length of CFCC strands, as a means of evaluating their bond characteristics. Development length tests and flexural tests were performed on two of the 40-ft piles at the FDOT Marcus H. Ansley Structures Research Center to further assess the performance of the CFCC strands. Lastly, the two 100-ft piles were driven at a bridge construction site, adjacent to standard steel-prestressed concrete piles. During driving operations, the behavior of the piles was monitored using embedded data collectors and a Pile Driving Analyzer®. The precasting efforts and test results show that the performance of piles prestressed with CFCC strands is comparable to those prestressed with steel. Using CFCC strands in prestressed concrete piles for bridge foundations, particularly in harsh environments, could potentially result in bridges that require less maintenance and have longer lifespans.
Fault Diagnosis and CAN Bus/Ethernet Redundancy Design of a Monitoring and Control System
The ship monitoring system is used to monitor and control the working status of various equipment on the ship. The navigational safety of the ship is affected directly by the stable working of the monitoring system. In this paper, a ship monitoring system with fault-type judgment function and bus redundancy is designed to improve system reliability and reduce fault checking cost. A redundant Ethernet/CAN bus communication network is constructed in the system, which connects multiple simulation nodes. The simulation node can simulate the faults that may occur during the communication process and feeds back the fault information to the host computer. The host computer will analyze and display the corresponding fault type on the user interface with the feedback information is received. The system reconfigures the network route autonomously when the simulation node has a communication fault. Routing of fault nodes can be switched to redundant routing, and the load balancing of the communication network can be maintained. Through experimental tests, the system can accurately locate faults and achieve fast switching of redundant routes between buses. Hence, the reliability of data transmission is improved.