David Sanders, University of Nevada, Reno, PI Abdeldjelil DJ Belarbi, University of Missouri, Rolla, Co-PI Shirley Dyke, Washington University, Co-PI Amr Elnashai, University of Illinois, Urbana-Champaign, Co-PI Jian Zhang, University of California, Los Angeles, Co-PI
Bridge columns are subjected to combinations of actions and deformations, caused by spatially-complex earthquake ground motions, features of structural configurations and the interaction between input and response characteristics. Combined actions/loadings can have significant effects on the force and deformation capacity of reinforced concrete columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. These effects should be considered in earthquake analysis and design of bridges so that significant earthquake damage and severe disruption of transportation systems can be reduced. The objectives of the project are to develop a fundamental knowledge of the impact of combined actions on column performance and system response and to establish analysis and design procedures that include the impact at both the component and system levels. The objectives will be realized by integrating analytical and experimental research where physical tests are driven by analyses and simulations that examine the system response of various bridge types under different loading conditions. The analytical models are calibrated by experimental data and then extended to system response.
The experimental program includes quasi-static testing of twenty-four large columns (fourteen will be funded by NEES) providing fundamental behavior including the impact of torsional moments at University of Missouri, Rolla (UMR), pseudo-dynamic testing of three large and four small scale columns with variable axial load, within a bridge system simulation, at the University of Illinois at Urbana-Champaign (UIUC), real-time dynamic testing of eight large scale columns with bidirectional, torsional and variable axial load inputs at University of Nevada, Reno (UNR), four tests provided by the University of Mexico (UNAM), plus an integrated experiment with three columns linked through simulation, conducted at UIUC by UMR. Fragility analysis will be undertaken, leading to the derivation of probabilistically-based fragility relationships for bridges subjected to combined action. Simplified analysis and design tools will be developed as well as the necessary code language to change the existing practice. Design and analysis methods will be derived that will affect the earthquake design practice in the US and internationally. Coordination of an integrated test program has already begun between the US and Japanese researchers. Analysis components will be done at UCLA, UIUC, UMR and UNR.
An integrated education, training and outreach program, lead by Washington University, will span from 4th graders to practicing engineers. Modules will be developed for teachers and professors that can be inserted in their courses. Modules will be used by the research team in summer camps, visits to local elementary, middle and high schools, undergraduate and graduate courses and in continuing education courses. Specific programs are targeted towards underrepresented groups. To achieve its objectives, the project will utilize the NEESit cyber-infrastructure, state-of-the-art instrumentation and high-speed data acquisition systems, the NEES equipment sites at UNR and UIUC and the non-NEES site at UMR, which has committed to joining NEESgrid.
Bridge columns are subjected to combinations of actions and deformations when subjected to earthquake ground motions. These actions are amplified when structural configurations are complex and structures are irregular. Combined actions/loadings can have significant effects on the force and deformation capacity of reinforced concrete columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. These effects should be considered in earthquake analysis and design of bridges so that significant earthquake damage and severe disruption of transportation systems can be reduced. Current analysis methods, behavior theories and design practices do not take into consideration the full range of interactions, due to the scarcity of experimental data and a lack of behavioral understanding. The project has developed fundamental knowledge of the impact of combined actions on column performance and system response and has establish analysis and design procedures that include the impact. The project integrated analytical and experimental research where physical tests are driven by analyses and simulations that examine the system response of various bridge types under different loading conditions, and analytical models are calibrated by experimental data. The experimental program includes quasi-static testing of large columns providing fundamental behavior including the impact of torsional moments at Missouri University of Science and Technology (MUST), pseudo-dynamic testing of large and small scale columns with variable axial load, within a bridge system simulation, at the University of Illinois at Urbana-Champaign (UIUC), real-time dynamic testing of large-scale columns with bidirectional motion, torsional and axial load at University of Nevada, Reno (UNR), plus an integrated experiment with three columns linked through simulation, conducted at UIUC by George Washington University in cooperation with the University of Houston. Extensive analytical work is being conducted at the sites listed plus at University of California Los Angeles. In addition, educational modules have been developed at Purdue University that integrates the experimental results into the classroom and help to explain basic earthquake behavior to students. Current the analytical tools that are used to design bridges do not combine the effects of torsion and bi-directional bending and shear. The outcome of this project will enable designers to include these combined effects and model bridges more accurately to the impacts of seismic loads. The project has addressed two critical issues for the future performance of bridges. These are (i) the effect of combined actions on the behavior and design of concrete bridge columns, and (ii) the interaction of these columns with the entire bridge system. The intellectual merit of the project therefore derives from addressing two related problems for which there is no current solution, and using the outcome to derive behavior models and design guidance to reduce damage and improve the safety of transportation systems in future earthquakes. The project will enable engineers to design and construct safer bridges. It is critical that our highway infrastructure remain open after an earthquake. The results of this project will help to improve the system reliability. The experimental data has been archived within NEES Data Repository for utilization by other researchers.
