![]() The fragility-informed approach for designing ABC bridge bents constructed with unbonded PT concrete columns presented is expected to promote post-earthquake serviceability and functional recovery after a large earthquake. The seismic performance of the ABC PT bridge bent using fragility analysis satisfied performance objectives similar to a monolithic CIP bent designed according to the latest seismic design codes in addition, the residual drift of the PT bent was practically zero. The seismic performance of the fragility-designed PT bridge bent is compared to that of a bent with conventional cast-in-place (CIP) concrete columns using nonlinear time-history analysis. An ABC bridge bent with unbonded PT concrete columns is designed using the outcome of seismic fragility analysis. Using Webwall geocell for green faced walls enables near vertical faces to be built quickly and easily, with the added benefit of using site won materials as fill. The results show that PT concrete columns provide sufficient re-centering to the bridge bent so that it remains serviceable after a large earthquake. Probabilistic seismic hazard analysis is carried out using nonlinear time-history analysis for a set of eighty ground motions. Performance limits are defined for the bridge model using non-linear pushover analysis. to be 80 in strength and 85 in stiffness from the results of pushover. Seismic assessment of a two-column bridge bent constructed with precast PT concrete columns is carried out column height-to-width ratio and ratio of initial posttensioning force to axial column capacity are selected as the assessment parameters. simulation tests to identify the seismic weakness of reinforced concrete (RC). A numerical model is developed for rocking columns which is validated using published data. Decreasing slab stiffness by 90 almost does not affect the model shear and bending capacities. 11 15 and 30, respectively, and reducing column stiffness by 60 decreased the shear and bending capacities by more than 30 and 40, respectively. KEYWORDS: Effective Stiffness, seismic analysis, member properties, lateral displacements. STIFFNESS EFFECTS OF STRUCTURAL ELEMENTS ON THE SEISMIC RESPONSE. Precast unbonded post-tensioned (PT) concrete columns are protected from damage due to their ability to mitigate seismic demand through rocking. seismic standards specify displacements are computed by factoring elastic displacements from analysis, therefore using reduced inertias a substantial increase of estimated displacements would occur produced turning analysis into over conservative. For vertical load analysis reinforced concrete cap stiffness can be reduced by half, but columns shall have gross properties since flexutral demans are low under static loads. Concrete columns are prefabricated and connected together with footings and cap beams using either grouted splice sleeves, socket connections, or through post-tensioning. The pier bent in question is a conventional three column highway overpass 60 feet long, 20 feet high, and having approximately 3.5 x 3.5 columns and cap. ![]() Accelerated Bridge Construction (ABC) is playing an increasingly large role in bridge construction within urban centers due to faster installation, improved quality and lower cost.
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