scholarly journals Effect of Near-Fault Pulsed Ground Motions on Seismic Response and Seismic Performance to Tunnel Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Xiancheng Mei ◽  
Qian Sheng ◽  
Zhen Cui
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Objective Assessment ◽  
Design Stage ◽  
Tunnel Structure ◽  
Response Behavior ◽  
Velocity Pulse ◽  
Near Fault

Seismic analysis of tunnels close to or crossing seismogenic faults is a complex problem, which is often neglected at the design stage for the lack of specific codes or guidelines and also because underground structures are considered less vulnerable than that of the corresponding above-ground facilities. Near-fault ground motions are generally assumed to providing more powerful energy to tunnel structures. Therefore, a recently developed velocity pulse equivalent model is proposed to synthesize the artificial near-fault pulsed ground motion for the seismic response behavior of the tunnel structure. A newly proposed nonlinear dynamic time history methodology, the incremental dynamic analysis method, is introduced into the analysis of seismic performance and fragility for tunnel structures. This study takes the Zheduoshan tunnel as a case study to illustrate the effects of velocity pulse on the seismic response behavior and seismic performance. The applicability of different seismic intensity measures is preliminarily discussed, and the vulnerability of the tunnel structure at different characteristic locations is analyzed. Afterward, the seismic vulnerability probabilities of the tunnel structure under the action of the near-fault pulsed ground motions and the far-field ground motions are presented, and then, the failure probabilities of the tunnel structure under the three-level support requirements are obtained. Research results provide an objective assessment of the velocity pulse effects and acts as a reference for the likely seismic damage assessment of tunnel structures.

Seismic Performance of Base-Isolation Building Subjected to Near-Fault Ground Motion with Velocity Pulse

2014 ◽  
Vol 580-583 ◽  
pp. 1700-1703
Author(s):  
Qiu Mei He ◽  
Ya Qi Li ◽  
Ya Min Zhao ◽  
Yu Yang
Keyword(s):  
Seismic Response ◽  
Seismic Performance ◽  
Base Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Structure ◽  
Velocity Pulse ◽  
Near Fault ◽  
Rubber Bearings

The seismic response of the base-isolated structure can be reduced significantly in the far-field region compared to the conventional seismic structure. However, near-fault ground motions with velocity pulse may cause the adverse influence on the seismic performance of the base-isolation building, which needs to be investigated deeply. In this paper 6 ground motions with velocity pulse are selected as the input, and the seismic response of a 9 layers conventional seismic RC frame building and comparative base-isolation building with lead-core rubber bearings are obtained by nonlinear time history analysis. The result indicates that base-isolation building with lead-core rubber bearings are of good aseismic performance under the near-fault ground motions with velocity pulse.

Shaking Table Tests of a Reduced-Scale UHV Transmission Tower-Line System Subjected to Near-Fault Ground Motions

2020 ◽  
Vol 20 (06) ◽  
pp. 2040015 ◽  
Author(s):  
Li Tian ◽  
Mengyao Zhou ◽  
Haiyang Pan ◽  
Aiqiang Xin ◽  
Yuping Liu
Keyword(s):  
Seismic Performance ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Transmission System ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Transmission Systems ◽  
Line System ◽  
Near Fault ◽  
Reduced Scale

An ultra-high voltage (UHV) transmission system offers higher bulk capacity and transmission over longer distances compared with conventional transmission systems, and the dynamic responses of such systems have attracted the interest of researchers. This paper focuses on an experimental investigation of the seismic performance of a 1000 kV UHV transmission system subjected to near-fault ground motions. To reproduce the genuine structural responses, a 1:25 reduced-scale experimental model was designed and constructed based on Buckingham’s theorem. Four kinds of typical natural seismic records were selected, namely, far-field, pulseless near-fault, forward-directivity near-fault and fling-step near-fault ground motions, and shaking table tests were subsequently carried out. Furthermore, the influences of the coupling effect between towers and lines, two-component ground motions, and the near-fault effect on the seismic response were investigated. The results demonstrate that the above three factors have a significant influence on the structural response and should not be neglected in seismic analysis. This research enriches the available experimental data and provides a more comprehensive understanding of the seismic performance of UHV transmission systems.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

scholarly journals Seismic Response Analysis and Control of Frame Structures with Soft First Storey under Near-Fault Ground Motions

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chunyang Liu ◽  
Peng Sun ◽  
Ruofan Shi
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Seismic Performance ◽  
Frame Structures ◽  
Response Analysis ◽  
Main Structure ◽  
Response Characteristics ◽  
Near Fault ◽  
Buckling Restrained Brace ◽  
Near Fault Ground Motion

This paper proposes two kinds of arrangements of buckling-restrained brace dampers to strengthen soft-first-storey structures locally. Two types of near-fault ground motion, with and without pulse, were selected for a study of the seismic response characteristics of soft-first-storey structures with and without buckling-restrained brace dampers, and the effects of different bracing arrangements on improving the seismic performance of soft-first-storey structures were recognized. The results show that, compared with pulse-free ground motion, near-fault pulsed ground motion results in a more severe seismic response in soft-first-storey frame structures, leading to more serious and rapid destruction of the main structure. Buckling-restrained brace dampers have an obvious energy dissipation effect, play a better role in protecting the main structure, and have good practicality. Compared with structures in which the buckling-restrained brace dampers are arranged only on the bottommost layer, the bottom-four-layer-support structure is more advantageous in terms of seismic performance.

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