Service Response and Evaluation of Prestressed Concrete Bridges through Load Testing

摘要

During the last two decades, self-consolidating concrete (SCC) has emerged as an alternative to produce structures with longer life expectancy. Despite the advantages that come with using SCC, there are some concerns related to its structural and serviceability response. The effect of the larger paste content and smaller coarse aggregate size is of particular interest because this combination may inhibit the development of the SCC's target mechanical properties. Field tests are an effective method to monitor the service response of infrastructure. In addition, field tests have largely confirmed reserves of strength capacity in existing bridges despite their visual condition and age. Sources that explain the difference in the reported strength capacity are diverse and may be attributed to in-situ parameters that are not considered during the design or evaluation of a bridge. This study aimed at presenting an evaluation protocol using experimental data to obtain the load rating of prestressed concrete bridges in Load and Resistance Factor Rating (LRFR) format. The proposed experimental evaluation approach will enable bridge owners to estimate, isolate and remove the unreliable parameters' contribution from a bridge load rating. Bridge A7957 is the first implementation project executed by MoDOT using high-strength and normal-strength SCC in prestressed concrete members. In addition, Bridge A7957 was a unique opportunity to monitor and establish the baseline service response and strength capacity of its main supporting members. The proposed experimental data and evaluation methodology are expected to encourage more discussion among bridge evaluators to better understand and improve current bridge analysis and evaluation practices of prestressed concrete bridges.