Journal of Infrastructure Systems

Optimal costing of structures requires taking into account lifetime management (inspection and maintenance) costs in addition to initial construction cost. Recently published papers on lifetime costing have used Markov decision process models to incorporate management policies into structural reliability analysis. In this paper, an optimization model is described based on partially observable Markov decision processes. The model depicts varying levels of uncertainty inherent in differing inspection techniques. The costs and inherent uncertainties of these techniques are related to environmental degradation from fatigue and corrosion processes. The mathematical approach leads to a management policy that explicitly includes frequency and type of inspection and extent of repair. The model is demonstrated in an example involving the management of a steel girder highway bridge.

Most infrastructures are made up of large number of parts, such as truss members and bridge decks. Relative movement of the connections between members causes load redistribution or even failure. Monitoring the integrity of the structural system can assure its performance and safety. TDR (time domain reflectometry) is proposed here as a multiple-points smart monitoring system using only one coaxial cable as the sensing and conducting medium all the way through the monitored structure. The cable is fixed at both ends of each pair of adjacent members to be the sensing device along itself. Relative movements between the members at the connecting points are monitored simultaneously by sending a fast-rise impulse into the cable. When lateral movement occurs, the cable will deform, having the effect of adding an equivalent capacitance at that point and causing the signature to jump up. When two adjacent blocks move apart from each other, the cable will be extended and cause its characteristic impedance change. The most important ability for a TDR system to have is to locate the relative movement along the cable that is very clearly shown in the time domain signature. The pulse of a TDR tester can go a few thousand feet, which gives enough monitoring range for most infrastructure.

Partnering traditionally refers to strategic alliances or agreements between private sector owners and construction contractors to work together for extended periods of time to deliver completed facilities. Private sector partnering typically begins before the preproject planning phase of a project. The public sector is constrained by laws that ensure the presence of fair competition in all contract awards and prohibits establishment of long-term relationships. Therefore, public sector partnering usually begins after the bid has been awarded for construction. Despite the existence of these constraints, the Texas Department of Transportation has been successful when partnering on a project-by-project basis. Quantitative data are presented that indicate partnering is having a positive effect on completion times, dispute resolution, and project team relations. Subjective data from nearly 900 participants are also provided that further support an emergence of partnering as a viable contract administration alternative for public sector infrastructure projects. Finally, based on the results of the analysis, conclusions and recommendations are presented to serve as benchmarks for future studies of the use of partnering on infrastructure projects.

Pavement temperature profile data can be quite useful in the analysis of stresses in jointed concrete pavements produced by temperature gradients within the slabs. Many stress analysis procedures consider the temperature gradients to be linear, though the actual vertical temperature distributions can be quite nonlinear. Errors produced by not considering the actual temperature gradients can be considerable. This work introduces the temperature-moment concept for characterizing temperature gradients in pavements. The procedure for reducing a temperature distribution into a single temperature-moment value is given, and an equation is provided for converting the temperature-moment into the actual moment produced in a pavement by a temperature gradient. An equation is also provided for converting the temperature-moment into the equivalent linear gradient that produces the same moment in the pavement. An example comparison between temperature-moment and measured curvature in a pavement slab is presented to illustrate the potential usefulness of the temperature-moment concept.