Analytical development and experimental validation of a structural-fuse bridge pier concept
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In this research, a structural fuse concept is proposed in which structural steel elements are added to a bridge bent to increase its strength and stiffness, and also designed to sustain the seismic demand and dissipate all the seismic energy through hysteretic behavior of the fuses, while keeping the gravity-resisting structural elements of the bridge bent elastic. A parametric study to investigate the effect of adding structural fuses to a RC bridge bent is first conducted. Trends in behavior as a function of key parameters defining the proposed structural fuse system are presented, followed by a proposed systematic design procedure. Then, an experimental program is developed for two large-scale twin-column segmental bridge bent specimens in an accelerated bridge construction application, having a series of structural fuses between the columns, and subjected to quasi-static cyclic tests to investigate the effect of adding these fuses on the total behavior of the system compared to the bare bents behavior. The experimental work is then followed by analytical work to replicate the experimental results obtained and to assess the adequacy of the design recommendations as well as the effectiveness of adding structural fuses to bridge bents for seismic energy dissipation, providing an insight into the general behavior of the structural fuse system. Two types of structural fuses are used in this second phase of work and implemented in this research; one is a newly proposed Buckling Restrained Braces (BRBs) concept for short length applications. The other is a special Steel Plate Shear Link (SPSL), which is a steel plate restrained against lateral buckling and designed and detailed to dissipate energy through shear yielding. Equations are developed to determine some critical design parameters of the SPSLs. Uniaxial cyclic tests are then performed on the individual BRBs that have been used as structural fuses in the large specimens, as the axial force resisted by each individual BRB could not be measured during the bridge pier tests. Also quasi-static cyclic testing is performed on individual SPSLs to investigate the behavior of these newly proposed links having different dimensions and lateral restraining conditions.