201 research outputs found
Analysis of Strain State and Cracking of Cocnrete Sleepers
Prestressed concrete sleepers are the most common type of the sleepers used on the railroad. They serve as rail supports and absorb loads induced by trains. Sleepers are important for the durability and safety of the railroad and are exposed to various loads and an agressive environment during exploitation. Therefore, different types of appearing damage can determine their reliability. The article briefly discusses possible causes of damage and the deterioration of prestressed concrete sleepers. End cracking and damage at the rail seat was determined during the inspection of used sleepers. Therefore, the strain state and cracking of the rail seat of the sleeper was analysed under static and dynamic loads. The paper provides the obtained results of experimental research of used and new sleepers
Reliability, risk and lifetime distributions as performance indicators for life-cycle maintenance of deteriorating structures
This is the author’s version of a work that was accepted for publication in Reliability Engineering & System Safety. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.ress.2013.09.013Structural capacity deterioration is among the main causes of increasing failure probabilities
of structural systems, thus maintenance interventions are a crucial task for their rational
management. Several probabilistic approaches have been proposed during the last decades for
the determination of cost-effective maintenance strategies based on selected performance
indicators. However, benefits and drawbacks of each performance indicator with respect to
the others should be further analyzed. The objective of this paper is to investigate
probabilistic approaches based on the annual reliability index, annual risk, and lifetime
distributions for life-cycle maintenance of structural systems. Maintenance schedules are
obtained for representative series, parallel, and series-parallel systems considering total
restoration of component resistances whenever a prescribed threshold, based on a selected
performance indicator, is reached. Effects related to different structural configurations and
correlation among failure modes are investigated. The superstructure of an existing bridge is
used to illustrate the presented approaches
Prediction of combined effects of fibers and nanosilica on the mechanical properties of self-compacting concrete using artificial neural network
Long-term Durability Models of Concrete in Highway Bridges, and Practical Approaches to Durability-Based Design
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