Mark Anthony Treacy

Monitoring of traffic action local effects in highway bridge deck slabs and the influence of measurement duration on extreme value estimates

In recent years, monitoring has offered a viable complement or even alternative to traditional analytical safety verification approaches. However, there still remains a lack of guidance for the use of monitored data in safety verification work. Limited resources often necessitate relatively short time frames for safety verification of problematic bridges. While the duration of monitoring is always an important consideration, it is rarely examined explicitly in terms of its influence on the predicted characteristic action effects. This work gives a novel approach for determining if a monitoring regime is sufficiently long to obtain a reliable extreme value estimate of the action effect. A case study of a highway bridge in Switzerland, with one year of continuous high-frequency measurements, is used to exemplify the approaches developed. The focus is on direct measurement of the traffic action effects in the bridges deck slab reinforcement. A comprehensive statistical approach for determination of site-specific, element-specific extreme traffic action effects is presented.

Extreme action effects in reinforced concrete bridges from monitoring

The need to maximise the lifetime of existing road bridges necessitates clear and efficient tools for engineers to perform structural safety verifications based on monitored data. This study develops methodologies for ultimate limit safety (ULS) verification of reinforced concrete elements using directly measured action effects. The paper incorporates results from a prestressed concrete highway bridge in Switzerland equipped with a structural health monitoring (SHM) system. The design considerations for the monitoring regime are presented. Estimates of the extreme traffic action effects for a given return period are obtained from daily block maxima results using a generalised extreme value approach. A number of factors are found to have a significant effect on the observed results, most notably the duration of monitoring.