Optimal inspection scheduling with alternative fatigue reliability formulations for steel bridges
نویسنده
چکیده
A reliability-based method for inspection scheduling of steel bridges is proposed to yield the optimal (most economical) inspection strategy that meets an acceptable safety level through the planned service life. Two fatigue reliability formulations that can be applied for most details in steel bridges are presented. For details classified according to AASHTO fatigue categories, a limit state function related to the number of stress cycles to failure based on Miner’s rule is used to evaluate the fatigue reliability; for details not classified according to AASHTO fatigue categories, a limit state function related to crack size and growth rate is used to evaluate the fatigue reliability. The inspection scheduling problem is modeled as an optimization problem with an objective function that includes the total expected cost of inspection, repair, and failure formulated using an event tree approach, appropriate constraints on the interval between inspections, and a specified minimally acceptable (target) structural reliability. An optimal inspection-scheduling plan can thus be developed for any specified fatigue details or fracture-critical sections in steel bridges. Examples presented demonstrate the advantage of the reliability-based optimal inspection scheduling in cost saving and structural reliability control over alternative inspection plans. Two case studies related to steel bridges – one for a plate girder and the other for a box girder – are presented to demonstrate the proposed reliability-based optimal inspection scheduling procedure.
منابع مشابه
Reliability-based Optimal Inspection for Fracture-critical Steel Bridge Members
To prevent members in steel bridges from fatigue failure, one usually needs to perform frequent periodic bridge inspections and employ detailed inspection methods. This is especially true for fracture-critical members or details. Carrying out these inspections puts a large burden on a transportation agency’s bridge maintenance budget. A systematic reliability-based method for inspection schedul...
متن کاملSimulation-based Non-destructive Inspection Scheduling of Steel Bridges
A procedure for selecting an optimal NDI (non-destructive inspection) technique and associated schedule for fracture-critical member inspections on a specific steel bridge is presented. Information related to the probability of detection (POD) function (a measure of inspection quality) of alternative NDI techniques is utilized. Calculations based on use of the POD function together with Monte C...
متن کاملProbabilistic Fatigue Life Updating for Railway Bridges Based on Local Inspection and Repair
Railway bridges are exposed to repeated train loads, which may cause fatigue failure. As critical links in a transportation network, railway bridges are expected to survive for a target period of time, but sometimes they fail earlier than expected. To guarantee the target bridge life, bridge maintenance activities such as local inspection and repair should be undertaken properly. However, this ...
متن کاملConsiderations of Ndt Quality in Fracture-critical Inspections for Steel Bridges
Non-destructive testing (NDI) techniques are routinely used in bridge inspection. However, detection accuracy, accessibility, cost and consequences of false indication are all factors to consider when selecting the NDI techniques to be used. A probabilistic method is proposed to help select the most suitable NDI technique and an associated optimal schedule for fracture-critical member/detail in...
متن کاملMaintenance and Work-rest Scheduling in Human-machine System According to Fatigue and Reliability
Most manufacturers use human-machine systems to produce high-quality products. Dealing with human-machine systems is very complicated since not only machines should be utilized in proper condition but also appropriate environment should be provided for human resources. Most manufacturers have a maintenance plan for machines but many of them do not have a proper work-rest schedule for human reso...
متن کامل