## 1 Introduction
[11] focused on the effectiveness of the capacity design procedure in the design of a tall-pier bridge. The investigation showed that the positions of plastic hinges did not match with the common assumption, due to the contributions of the inertial forces of the piers. Currently, due to the limited investigations and lack of suitable design codes or specifications, the seismic design of tall-pier bridges remains an aimless and casual design. In the Specifications for Seismic Design of Highway Bridges (JTG/T 2231-01-2020) [12], it is required that specified research needs to be conducted if the maximum pier height exceeds 40 m or the effective mass of the first mode of the pier is less than 60%. The AASHTO Guide Specifications for LRFD Seismic Bridge Design [3] and CALTRANS Seismic Design Criteria [13] are only appliable to regular bridges, whereas the tall-pier bridge belongs to the typical irregular bridges. In Eurocode 8 [14], for irregular bridges, the damping ratio of higher modes has a great influence on the calculated response spectrum so that the multi-degree-of-freedom model is usually employed. The difference between the tall pier and medium or short pier is not considered. In the specifications for highway bridges in Japan [15], there are no specified definitions for the tall, medium or short pier. The above-mentioned research points out that the seismic design of regular bridges is not applicable to tall-pier bridges, which does not meet the definition of the regular bridge. Currently, the design method of regular medium to short pier is still applied in the design of tall-pier bridges, which is aimless and insufficient. During the Great Wenchuan Earthquake, the Mazoiping Bridge and Luzipingpu Bridge and other tall-pier bridges experienced severe damage and loss of function [16]. Compared with the far-fault ground motions, the characteristics of the near-fault ground motions are quite different. The ground motions are characterized by intense pulse, long pulse period and large fault displacement, which lead to the energy accumulation in a short time and thus damage the structures [17]. In the Imperial Valley earthquake (1979), the Northridge earthquake (1994), the Kobe earthquake (1995), and the Chi-Chi earthquake (1999), the damage and collapse of a large number of structures under near-fault ground motions caused the widespread concern among scholars. [PERSON] and [PERSON] [18] demonstrated that the relationship between the acceleration pulse duration and the fundamental period of the structure greatly affected the structural seismic performance. The results revealed that the more serious damage would occur when the pulse duration is much larger than the structural period. [PERSON] et al. [19] analyzed effects of rupture directivity on the amplitude and duration of strong ground motion. It is found that the elastic response spectrum of pulse-type ground motion was larger than that of non-pulse ground motion for periods longer than 0.6 s. Also, many other scholars concluded that near-fault ground motions with pulses greatly affected the seismic performance of the structures with a medium fundamental period. [PERSON] and [PERSON] [20] analyzed the influence of the dynamic response of a steel frame structure subjected to the near-fault earthquake. The results showed that compared with the far-fault ground motions, the velocity pulse in near-fault ground motions would cause the structure to dissipate considerable input energy in relatively few plastic cycles. To sum up, structures will experience more serious damage when subjected to near-fault ground motions with pulses. Due to the lack of specialized seismic design concepts and design methods for RC tall-pier bridges, excessive displacement and deformation of the bridge may occur under near-fault ground motions, leading to severe structural damage, which requires costly and time-consuming repair, and even replacement [16; 21]. How to improve the seismic performance of the tall-pier bridge under near-fault ground motion has become an urgent problem.