scholarly journals Hybrid Simulation of Seismic Responses of a Typical Station with a Reinforced Concrete Column

2020 ◽  
Vol 10 (4) ◽  
pp. 1331 ◽  
Author(s):  
Xuesong Cai ◽  
Chengyu Yang ◽  
Yong Yuan
Keyword(s):  
Reinforced Concrete ◽  
Failure Process ◽  
Hybrid Simulation ◽  
Test Method ◽  
Shaking Table ◽  
Subway Station ◽  
Test Results ◽  
Earthquake Excitation ◽  
Simulation Process ◽  
Central Column

During the 1995 Kobe earthquake, damages were observed in the Daikai subway station and adjacent tunnels. It was the first large-scale underground structure that failed under the earthquake excitation. Numerical and experimental analyses have been conducted to study the failure process of the Daikai station. However, the issue of the scale ratio still exists in the shaking table tests of underground structures. In order to tackle this issue, a hybrid simulation technique is developed here to study the seismic performance of a typical subway station. Based on the previous research, it is found that the central column is the critical component of the structure. Therefore, a reinforced concrete central column is physically tested in the hybrid simulation process. On the other hand, the remaining parts of the structure and soil domain are numerically modeled at the same time. Four hybrid simulation cases are conducted with peak ground accelerations of 0.01 g, 0.1 g, 0.22 g, and 0.58 g. The test results of displacement and shear force are compared with the analytical results. Moreover, the good agreement between the test results and numerical results validate the accuracy of the proposed hybrid test method. After the hybrid simulation process, a quasi-static test is conducted to illustrate the mechanical properties of the central column after the earthquake excitation.

Influence of Cavity above Tunnel on Stratum Deformation and Failure in Urban Tunnelling

2012 ◽  
Vol 170-173 ◽  
pp. 1810-1815
Author(s):  
Yanan Zhang ◽  
Cheng Ping Zhang ◽  
Qian Qian Li ◽  
Zheng Li ◽  
Yi Cai
Keyword(s):  
Failure Process ◽  
Test Method ◽  
Test Results ◽  
Tunnel Engineering ◽  
Deformation And Failure ◽  
Tunnel Section ◽  
Section Size ◽  
Ground Cavity ◽  
Stratum Deformation ◽  
Beijing Subway

In order to study the influence of cavity above the tunnel on stratum deformation and failure in urban tunnelling, the model test method was adopted based on the parameters of the stratum and tunnel section size in Beijing subway. The stratum responses were obtained under the conditions without ground cavity and with ground cavity above the tunnel. The responses include the stratum stress distribution, stratum settlement law and stratum failure process. It was concluded that the existence of ground cavity above the tunnel worsened the stratum condition and accelerated the progress of stratum deformation and failure. Furthermore, the failure began from the cavity and the damage scope was bigger than that under the condition without cavity according to the test results. The research results can be referenced for the similar tunnel engineering.

scholarly journals Mixed Sensitivity-Based Robust H∞ Control Method for Real-Time Hybrid Simulation

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 840
Author(s):  
Xizhan Ning
Keyword(s):  
Real Time ◽  
Control Method ◽  
Weighting Function ◽  
Hybrid Simulation ◽  
Shaking Table ◽  
Transfer System ◽  
Hydraulic Actuator ◽  
Earthquake Excitation ◽  
Engineering Structures ◽  
Weighting Functions

Real-time hybrid simulation (RTHS), dividing the emulated structure into numerical substructures (NS) and physical substructures (PS), is a powerful technique to obtain responses and then to assess the seismic performance of civil engineering structures. A transfer system, a servo-hydraulic actuator or shaking table, is used to apply boundary conditions between the two substructures. However, the servo-hydraulic actuator is inherently a complex system with nonlinearities and may introduce time delays into the RTHS, which will decrease the accuracy and stability of the RTHS. Moreover, there are various uncertainties in RTHS. An accurate and robust actuator control strategy is necessary to guarantee reliable simulation results. Therefore, a mixed sensitivity-based H∞ control method was proposed for RTHS. In H∞ control, the dynamics and robustness of the closed-loop transfer system are realized by performance weighting functions. A form of weighting function was given considering the requirement in RTHS. The influence of the weighting functions on the dynamics was investigated. Numerical simulations and actual RTHSs were carried out under symmetric and asymmetric dynamic loads, namely sinusoidal and earthquake excitation, respectively. Results indicated that the H∞ control method used for RTHS is feasible, and it exhibits an excellent tracking performance and robustness.

scholarly journals Hybrid Simulation of Soil Station System Response to Two-Dimensional Earthquake Excitation

2019 ◽  
Vol 11 (9) ◽  
pp. 2582 ◽  
Author(s):  
Cheng-Yu Yang ◽  
Xue-Song Cai ◽  
Yong Yuan ◽  
Yuan-Chi Ma
Keyword(s):  
Mechanical Properties ◽  
Hybrid Simulation ◽  
System Response ◽  
Two Dimensional ◽  
Test Results ◽  
Earthquake Excitation ◽  
Steel Column ◽  
Intermediate Column ◽  
Hybrid Test ◽  
Seismic Behaviors

Soil station system seismic issues have been highly valued in recent years. In order to investigate the dynamic seismic behaviors of the intermediate column in soil station systems, a hybrid test of a soil station system was conducted. The soil station model was performed with OpenSees. Virtual hybrid simulation was fulfilled with adapter elements. A hybrid model, composed of the steel column specimen and the remainder numerical model, was assembled using the OpenFresco framework. An intermediate column was treated as the physical substructure, while the rest of the soil station system was treated as the numerical substructure in a hybrid simulation. The hybrid test results are compared with the analytical results. The data obtained from such tests show that the system can accurately reflect the mechanical properties of intermediate columns in soil station systems. A hybrid simulation would be a proper way to assess the seismic performance of a soil station system.

Shaking Table Test of Reinforced Concrete Frame-Wall Model

2014 ◽  
Vol 580-583 ◽  
pp. 1467-1470
Author(s):  
Hao Zhang ◽  
Bing Li ◽  
Xu Li ◽  
De Bin Wang
Keyword(s):  
Reinforced Concrete ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Engineering Practice ◽  
Seismic Action ◽  
Test Results ◽  
Structural Members ◽  
Reinforced Concrete Frame ◽  
Wall Model ◽  
Concrete Frame

A 1/5 scaled three-story RC (reinforced concrete) frame-wall model was modeled in microconcrete and fine wire and carried out on the shaking table. The main objective of this paper aimed to investigate the dynamic characteristics, the seismic responses, and the failure mechanisms of the model, also concentrated on the strain rate of concrete on structural members under seismic action. Based on the test results, some significant conclusions are obtained for engineering practice.

Experimental Study on the Seismic Behavior of Semi-Precast Reinforced Concrete High-Rise Buildings Using Shaking Table

2020 ◽  
Vol 897 ◽  
pp. 202-210
Author(s):  
Vo Thong Nguyen ◽  
Manh Hoang
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Shaking Table Test ◽  
Experimental Studies ◽  
Nonlinear Behavior ◽  
Test Method ◽  
Shaking Table ◽  
Construction Technology ◽  
High Rise ◽  
In Series

Currently, theoretical and experimental studies on the overall behavior of semi-precast reinforced concrete high-rise buildings subjected to the earthquake are limited. These studies have mostly focused on the behavior of either joints or frames. To study the overall behavior of a structure under an earthquake, one of the best methods is to do the seismic shaking table test. This paper presents the results of an experimental study on the overall behavior of a semi-precast reinforced concrete multi-story building, which uses new design and construction technology, by using the seismic shaking table test method. These buildings are constructing in series in Vietnam. This research carried out both the linear and nonlinear behavior of the structure until the stage of near collapse. The study consists of three main steps: designing the simulating model; establishing a process to generate artificial accelerograms which are in accordance with the seismic characteristics in Vietnam; testing the 12-story semi-precast model to verify theoretical predictions.

Adding an expansive agent to increase the toughness of steel fibre reinforced concrete

2019 ◽  
Vol 26 (4) ◽  
pp. 197-208
Author(s):  
Leo Gu Li ◽  
Albert Kwok Hung Kwan
Keyword(s):  
Reinforced Concrete ◽  
Steel Fibre ◽  
The Other ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Compressive Properties ◽  
Shrinkage Cracking ◽  
Steel Fibre Reinforced Concrete ◽  
Expansive Agent ◽  
Concrete Matrix

Previous research studies have indicated that using fibres to improve crack resistance and applying expansive agent (EA) to compensate shrinkage are both effective methods to mitigate shrinkage cracking of concrete, and the additions of both fibres and EA can enhance the other performance attributes of concrete. In this study, an EA was added to fibre reinforced concrete (FRC) to produce concrete mixes with various water/binder (W/B) ratios, steel fibre (SF) contents and EA contents for testing of their workability and compressive properties. The test results showed that adding EA would slightly increase the superplasticiser (SP) demand and decrease the compressive strength, Young’s modulus and Poisson’s ratio, but significantly improve the toughness and specific toughness of the steel FRC produced. Such improvement in toughness may be attributed to the pre-stress of the concrete matrix and the confinement effect of the SFs due to the expansion of the concrete and the restraint of the SFs against such expansion.

On axial compressive behavior of steel fiber reinforced concrete confined by FRP

2021 ◽  
pp. 136943322098165
Author(s):  
Hossein Saberi ◽  
Farzad Hatami ◽  
Alireza Rahai
Keyword(s):  
Reinforced Concrete ◽  
Experimental Test ◽  
Steel Fiber ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Frp Confinement

In this study, the co-effects of steel fibers and FRP confinement on the concrete behavior under the axial compression load are investigated. Thus, the experimental tests were conducted on 18 steel fiber-reinforced concrete (SFRC) specimens confined by FRP. Moreover, 24 existing experimental test results of FRP-confined specimens tested under axial compression are gathered to compile a reliable database for developing a mathematical model. In the conducted experimental tests, the concrete strength was varied as 26 MPa and 32.5 MPa and the steel fiber content was varied as 0.0%, 1.5%, and 3%. The specimens were confined with one and two layers of glass fiber reinforced polymer (GFRP) sheet. The experimental test results show that simultaneously using the steel fibers and FRP confinement in concrete not only significantly increases the peak strength and ultimate strain of concrete but also solves the issue of sudden failure in the FRP-confined concrete. The simulations confirm that the results of the proposed model are in good agreement with those of experimental tests.

Finite Element Analysis of Reinforced Concrete Beams with Exterior FRP Shell

2011 ◽  
Vol 243-249 ◽  
pp. 1461-1465
Author(s):  
Chuan Min Zhang ◽  
Chao He Chen ◽  
Ye Fan Chen
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Contact Interface ◽  
Accurate Calculation ◽  
Element Analysis

The paper makes an analysis of the reinforced concrete beams with exterior FRP Shell in Finite Element, and compares it with the test results. The results show that, by means of this model, mechanical properties of reinforced concrete beams with exterior FRP shell can be predicted better. However, the larger the load, the larger deviation between calculated values and test values. Hence, if more accurate calculation is required, issues of contact interface between the reinforced concrete beams and the FRP shell should be taken into consideration.

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