Temperature-induced changes in bridge structural response observed during static load testing using distributed fiber optic sensing

Résumé fourni par la source

Bridges are continuously exposed to temperature variations caused by solar radiation and environmental conditions. These fluctuations induce global structural deformations and stress redistributions due to material properties, structural configurations, and boundary restraints. Temperature also affects structural health monitoring sensors, which may produce biased outputs if thermal effects are not properly compensated. Understanding both structural and sensor-related thermal influences is therefore essential for the reliable interpretation of monitoring data in existing bridges. This study investigates the influence of temperature on static load test results using an integrated monitoring system composed of distributed fiber optic sensing (DFOS) and linear variable differential transformers (LVDTs). The high spatial resolution of DFOS provides continuous strain measurements along the bridge girders, while LVDTs record discrete local displacements. Particular attention is given to separating mechanically induced strain from temperature-related effects at both the structural and sensor levels. The most appropriate temperature compensation strategies are therefore investigated to isolate the structural response due to external loading. The methodology is applied to a prestressed concrete bridge in Switzerland through nine static load tests performed with a truck positioned at different locations along the bridge span. The results highlight the significant impact of temperature on both structural response and sensor measurements. After temperature compensation, bridge displacements predicted from DFOS measurements are compared with LVDT measurements, showing strong agreement and confirming the effectiveness of the proposed approach. These findings emphasize the crucial importance of properly accounting for thermal effects when interpreting monitoring data for existing bridges.

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