Seismic fragility assessment of bridges with as-built and retrofitted splice-deficient columns

Abstract

A significant proportion of existing bridges in high seismic regions were constructed prior to the 1970s. As a result of poor reinforcement detailing, pre-1970s bridge columns are susceptible to lap-splice or shear failure in the plastic region. Given the high economic impact of retrofitting all pre-1970s reinforced concrete (RC) bridges, it is essential to identify the most vulnerable bridges for retrofit prioritisation. Analytical fragility functions are useful for quantifying the seismic vulnerability of existing bridge stock. However, the accuracy of these fragility functions relies on the adequacy of the adopted modelling approach. This paper presents a hinge-type modelling approach for capturing the seismic response of as-built splice-deficient and retrofitted RC bridge columns. Fragility analysis is carried out for typical seat and diaphragm abutment two-span bridges using the proposed hinge-type modelling approach. The results showed that the vulnerability of the bridges depends on the column failure mode and the limit state under consideration. Also, the common notion that the column is the most vulnerable component may not necessarily be true. The study underscored that retrofitting columns without retrofitting other components may not effectively mitigate the damage and associated risk.

Numerical Simulation of Fiber-reinforced Concrete under Cyclic Loading using Extended Finite Element Method and Concrete Damaged Plasticity

“…During earthquakes, bridge columns are often the most vulnerable and deficient components, particularly when in moderate damage states [1]. Transverse stirrups in these columns are prone to deficiencies, leading to multiple damage states, ranging from concrete cracking to cover spalling, and eventually the failure of steel bars at the base of the columns.…”

Seismic performance evaluation of reinforced concrete frame with improper lap splices: A scaled-down experimental approach using micro-concrete

“…Some existing research has focused on the experimental evaluation of this defect concerning columns. For instance, the seismic fragility of RC structures with splice-deficient columns was studied experimentally (Opabola and Elwood 2021;Opabola and Mangalathu 2022). The results exhibited that the vulnerability of such RC structures is dependent on the failure mode of splice-deficient columns and the limit state under consideration.…”