About the research
A goal of the proposed work is to continue to improve the understanding of the true seismic behavior of a cap-to-girder connection that will facilitate ABC opportunities while mitigating the seismic hazard associated with bridge designs that utilize accelerated construction methods. To accomplish this purpose, we will design a prototype bridge and, using experimental and analysis methods, investigate the expected seismic performance of the girder-to-cap connection of the prototype.
Previous similar analytical work completed for the earlier inverted-tee project will be built upon to minimize the amount of analytical work associated with this investigation. The improved connection detail completed as part of the previous work will also be utilized again here to avoid unnecessary duplication of earlier work.
A large-scale bridge component test will be designed to replicate a portion of the prototype superstructure consisting of several precast I-girders and an inverted-tee pier cap using the girder-to-cap connection developed in the previous work. The model will be subjected to the seismic effects resulting from horizontal and vertical accelerations and fully quantify the elastic and plastic behavior of the connection. Using the test data, the accuracy of the analysis models will be evaluated.
The results of the experimental and analytical work will be used to create design guidelines, details, and examples that will enable increased use of accelerated bridge construction methods and increased understanding of how precast girder to cap connection should be detailed to address the concerns resulting from vertical ground acceleration. The research team will play a proactive role in disseminating project findings to Caltrans engineers and other interested designers and organizations and will also assist with rapidly deploying the research results into practice.
The inverted-tee test also revealed that use of untensioned, grouted tendons in the girder-to-cap might provide sufficient seismic resistance. The research team plans to develop individual component tests to compare the behavior of grouted tendons with different level of initial stresses and provide experimental behavior comparisons of the different options.
The research team is aware that in addition to the I-girder, Caltrans has utilized bulb-tee girders and perhaps even more commonly the California wide-flange (or super) girder. It is believed that experimental results established by using the I-girder configuration can also be applied to bulb-tee girders and the California Wide Flange Girder configuration. If needed, the experimental program could be altered to accommodate one of these girder types.