###### Abstract  
Current research trends in significant hydraulic engineering projects focus on investigating the seismological properties of intensity and frequency content of pulse-type near-field earthquakes on the structural response. Conversely, the duration impact is not expressly addressed in the seismic design code for underground buildings. Currently, various duration indicators of as-recorded strong ground motions mainly consider the effective duration of the initial acceleration component record. In contrast, the duration indicators for the effective velocity duration (EVD) of the original velocity time-history component record have rarely been addressed. Specifically, there is a gap between the effective velocity duration and the structural response. To illustrate the impact on the structural response, an EVD of pulse-type NFGM duration was used. This EVD can be calculated for seismic excitations with set threshold values that enable a quantitative examination of the duration effects. A fluid-hydraulic tunnel-rock interaction system was built and used to estimate the seismic response characteristics induced by different duration NFGMs. The investigation's findings highlight that the inelastic dynamic response and damage degree are strongly affected by the EVD. Additionally, the fixed threshold value of 5-95% showed an excellent correlation coefficient with the structural response. The significant duration was also found to be the most suitable alternative indicator to replace the EVD index. In addition, the reduced time-history methodology of near-fault earthquake records is presented and validated, with this method being used to improve the efficiency of the dynamic time-history analysis of hydraulic arched tunnels. effective velocity duration; pulse-type near-fault ground motions; hydraulic arched tunnel; structural response +
Footnote †: journal: Applied Sciences  
a severe collapse, demonstrating that structural safety is still an unavoidable problem [2]. This incident has spurred engineers and seismologists to try and further understand the structural response of underground structures in the face of seismological events. During the last few decades, seismologists and civil engineers have studied the characteristics of seismological events more precisely and have developed methods to identify several features [3]. Among the seismological features studied, the pulse-type near-fault ground motions (NFGMs) were extensively employed to examine the structural responses of high dams [4], bridges [5], and liquefaction events [6]. In particular, after several as-recorded extreme earthquake events, contemporary studies have revealed that the pulse-type NFGMs at short site-to-source distances were more destructive than those GMs at long distances [7; 8; 9; 10; 11]. Moreover, a wavelet analysis is conventionally used to illustrate the frequency content of the pulse-type NFGMs [12; 13; 14; 15; 16]. Additionally, the seismological characteristics of amplitude are one of the practical engineering parameters of structural response. This can be expressed by the peak value of the time-history curve of the GMs, such as the peak ground displacement (PGD), the velocity (PGV), and the acceleration (PGA). However, the current seismic design code does not take the duration of the pulse-type NFGMs into account, which may result in an underestimation of the structural response. Generally, observations from strong seismic events indicate that the length of duration of the pulse-type NFGMs may also be a critical factor in causing severe damage to underground structures. The structural response induced by the ground motion duration (GMD) effects has been extensively researched over the past few years. Currently, the applicability of dynamic response indicators of different types of structures to the GMD effects is inconsistent, since over 30 definitions of the GMD effects have been presented [17]. This phenomenon has led to a debate in the scientific community regarding the impact of the GMD effects on structural responses [18].