###### Abstract  
Despite the numerous advantages high-strength reinforcement (HSR) and high-strength concrete (HSC) offer over conventional materials, the practical use of these materials for bridge column design in seismic zones has somewhat been limited. This is due to the insufficient research data and guidelines for the seismic design of bridges using HSC and HSR and the lack of a reliable analytical model. Therefore, to address this issue and promote the application of HSR and HSC, this paper investigates high-strength bridge columns' seismic performance experimentally and numerically. Six large-scale reinforced concrete (RC) bridge columns and one multi-column bent frame were tested under a quasi-static cyclic loading with constant axial compression. The primary design parameters were axial load ratio, longitudinal and transverse reinforcement yield strength, and transverse reinforcement spacing. The failure pattern of high-strength columns was similar to conventional RC columns and satisfied the requirements for seismic design in terms of failure mode, hysteresis behavior, ductility, and energy dissipation capacity. The experimental ductility values of the high-strength columns were satisfactory and capable of meeting the ductility demand of most codes. Furthermore, a numerical model was built using the OpenSees program to predict the seismic performance of the specimens and then verified by comparing them with the test results of 12 columns. The numerical model's results were in good agreement with the experimental results. The results suggested that numerical modeling techniques commonly used for normal strength concrete (NSC) columns can be used for HSC bridge columns by incorporating a proper material model. b 2022 2022022022022022022022022022022022022022022022202220222202  
researchers have studied and compared the seismic performance of RC columns reinforced with different grades of rebar, ranging from normal strength reinforcement (NSR) grade 60 (420 MPa) to HSR grade 120 (830 MPa). The research findings conclude that satisfactory seismic performances of structures can be achieved using HSR grade 80 (550 MPa), grade 100 (690 MPa), and grade 120 (830 MPa) [13; 14; 15; 16; 17]. Similarly, research regarding the drift capacity of HSR and NSR was also conducted; the study concluded that the drift capacity of columns constructed with Grade 80 and Grade 120 longitudinal rebar (HSR) is comparable with columns constructed with Grade 60 longitudinal rebar (NSR) [13; 18]. These findings were later adopted into the lat-est ACI 318-19 [19] code provision that allows the use of grade 80 HSR in the special moment-resisting frames. As one of the most densely populated seismic zones, Taiwan has been actively researching the applicability of high-strength materials for the country's infrastructures. In 2008, the Taiwan New RC research project was launched to apply HSC and HSR to RC columns in high-rise buildings [20]. The Taiwan New RC project categorizes concrete as HSC if the minimum concrete compressive strength is 70 MPa and rebar as HSR if the yield stress is 685 MPa and 785 MPa for longitudinal rebar and transverse rebar, respectively. Since the project's launch, many studies have been conducted [21; 22; 23; 24] in an effort to draft the design guidelines for the use of HSC and HSR for RC structures [25]. However, all the research projects are limited to the application of HSC and HSR in high-rise RC buildings. Meanwhile, a bridge has a different structural configuration and often has all the seismic energy absorbed solely by the columns. Hence, stringent research shall also be conducted for the application of HSC and HSR in bridge columns. Although the AASTHO provision [26] specifies the permissible yield strength of grade 100 (690 MPa) rebar for designing and constructing some structural bridge members, its practical use in seismic zones has been limited due to the lack of experimental data [14]. Some of the available experimental studies are conducted by [PERSON] et al.