Preliminary study on the threshold stiffness and residual displacement of the multangular-pyramid concave friction system (MPCFS) for seismic isolation

2021 ◽  
pp. 136943322110093
Author(s):  
Xiong Wei ◽  
Jiang Li-Zhong ◽  
Li Yao-Zhuang
Keyword(s):  
Seismic Isolation ◽  
Central Point ◽  
Curved Surface ◽  
Engineering Practice ◽  
Ambient Vibrations ◽  
Residual Displacement ◽  
Building Model ◽  
Preliminary Study ◽  
Simulation Results ◽  
Storey Building

In this research, the threshold stiffness and residual displacement of the MPCFS are both investigated. The MPCFS has a higher threshold (breakaway) stiffness and no residual displacement after earthquakes or ambient vibrations, which makes it different from the conventional Curved Surface Slider (CSS). These two features can enable the MPCFS to be more stable when experiencing micro-to-small shakings, and always restore to its central point after earthquakes. With the aim of testifying the two features, a series of analytical simulations are conducted on a four-storey building model equipped with MPCFS. The analytical results are compared with that obtained with CSS. The simulation results validate the aforementioned virtues of MPCFS over the CSS. This indicates that MPCFS has great potential in the engineering practice of seismic isolation.

Performance of bi-directional elliptical rolling rods for base isolation of buildings under near-fault earthquakes

2017 ◽  
Vol 21 (5) ◽  
pp. 675-693 ◽  
Author(s):  
Aruna Rawat ◽  
Naseef Ummer ◽  
Vasant Matsagar
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Frictional Resistance ◽  
Curved Surface ◽  
Isolation System ◽  
Near Fault ◽  
Earthquake Ground Motions ◽  
Base Isolation System ◽  
Near Fault Earthquakes ◽  
Storey Building

Rolling base isolation system provides effective isolation to the structures from seismic base excitations by virtue of its low frictional resistance. Herein, dynamic analysis of flexible-shear type multi-storey building mounted on orthogonally placed elliptical rolling rod base isolation systems subjected to bi-directional components of near-fault earthquake ground motions is presented. The orthogonally placed rods would make it possible to resist the earthquake forces induced in the structure in both the horizontal directions. The curved surface of these elliptical rods has a self-restoring capability due to which the magnitude of peak isolator displacement and residual displacement is reduced. The roughness of the tempered curved surface of the rollers dissipates energy in motion due to frictional damping. The seismic performance of the multi-storey building mounted on the elliptical rolling rod base isolation system is compared with that mounted on the sliding pure-friction and cylindrical rolling rod systems. Parametric studies are conducted to examine the behavior of the building for different superstructure flexibilities, eccentricities of the elliptical rod, and coefficients of friction. It is concluded that the elliptical rolling rod base isolation system is effective in mitigation of damaging effects of the near-fault earthquake ground motions in the multi-storey buildings. Even under the near-fault earthquake ground motions, the base-isolated building mounted on the elliptical rolling rods shows considerable reduction in seismic response. The isolator displacement with the elliptical rolling rod base isolation system is less in comparison to the pure-friction and cylindrical rolling rod systems.

scholarly journals Discussion on the Theoretical Basis for Cross-Over Method Applied to Downhole Wave Velocity Test

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qing Dong ◽  
Zheng-hua Zhou ◽  
Su Jie ◽  
Bing Hao ◽  
Yuan-dong Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Wave Velocity ◽  
Theoretical Basis ◽  
Influence Factors ◽  
P Wave ◽  
Engineering Practice ◽  
S Wave ◽  
Simulation Results ◽  
The Cross

At engineering practice, the theoretical basis for the cross-over method, used to obtain shear wave arrival time in the downhole method of the wave velocity test by surface forward and backward strike, is that the polarity of P-wave keeps the same, while the polarity of S-wave transforms when the direction of strike inverted. However, the characteristics of signals recorded in tests are often found to conflict with this theoretical basis for the cross-over method, namely, the polarity of the P-wave also transforms under the action of surface forward and backward strike. Therefore, 3D finite element numerical simulations were conducted to study the validity of the theoretical basis for the cross-over method. The results show that both shear and compression waves are observed to be in 180° phase difference between horizontal signal traces, consistent with the direction of excitation generated by reversed impulse. Furthermore, numerical simulation results prove to be reliable by the analytic solution; it shows that the theoretical basis for the cross-over method applied to the downhole wave velocity test is improper. In meanwhile, numerical simulations reveal the factors (inclining excitation, geophone deflection, inclination, and background noise) that may cause the polarity of the P-wave not to reverse under surface forward and backward strike. Then, as to reduce the influence factors, we propose a method for the downhole wave velocity test under surface strike, the time difference of arrival is based between source peak and response peak, and numerical simulation results show that the S-wave velocity by this method is close to the theoretical S-wave velocity of soil.

Mechanical Performances of Transverse Rib Bar During Pull-Out Test

2019 ◽  
Vol 11 (05) ◽  
pp. 1950048 ◽  
Author(s):  
S. R. Wang ◽  
H. G. Xiao ◽  
Z. S. Zou ◽  
C. Cao ◽  
Y. H. Wang ◽  
...  
Keyword(s):  
Radial Stress ◽  
Failure Modes ◽  
Thick Wall ◽  
Engineering Practice ◽  
Pull Out ◽  
Inner Pressure ◽  
Steel Bar ◽  
Wedge Shape ◽  
Simulation Results ◽  
Mechanical Performances

To evaluate mechanical performances of the transverse rib bar and reveal anchoring mechanism between the grout and steel bar, a series of pull-out tests were carried out, the numerical simulations and theoretical analysis of grout failure modes were also analyzed. Results show that the grout in front of the transverse rib display wedge-shape damage and the simulation results verify this damage forms. The formula of the effective transverse rib angle, the grout strength and anchorage force were derived based on elastic thick-wall cylinder theory. During the pull-out tests, the radial stress of the grout lagged the tangential stress reaching the ultimate tensile strength with the inner pressure increasing. The anchoring force of the transverse rib bar increases with the increase of the grout strength, and with the increase of the effective transverse rib angle. These conclusions provide the theoretical basis and technical support for the engineering practice.

A study on seismic isolation of building used LRB

2020 ◽  
Vol 6 (2) ◽  
pp. 52
Author(s):  
Muhammet Yurdakul ◽  
Mehmet Burak Yıldız
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Dynamic Loads ◽  
Isolation System ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Earthquake Design ◽  
Base Isolation System ◽  
Internal Forces ◽  
Storey Building

Base isolation system with lead rubber bearing (LRB) is commonly used to prevent structure against to damage of earthquake. Design of LRB system is detailed in this study. The isolated building with LRB design according to Uniform Building Code (UBC-97) and fixed building were examined. The six-storey building with LRB and fixed building were modelled in SAP2000 with the same dynamic loads. The relative floor displacement and internal forces of the seismic isolated and fixed building are compared. In addition, transverse and longitudinal reinforcement of any axis of seismic isolated and fixed building are compared. Analyse results showed that effectiveness of using seismic isolation system on building. The weight of longitudinal and transverse reinforcement of isolated building is smaller than fixed building about 36%, 40% respectively.

Velocity and Attitude Matching of Transfer Alignment by Using H∞ Filter

2012 ◽  
Vol 433-440 ◽  
pp. 4861-4864 ◽  
Author(s):  
Li Jun Song ◽  
Deng Feng Cheng ◽  
Wei Lu
Keyword(s):  
Kalman Filter ◽  
White Noise ◽  
Estimation Method ◽  
Measurement Noise ◽  
Engineering Practice ◽  
Transfer Alignment ◽  
Color Noise ◽  
System Noise ◽  
Simulation Results

The H∞ filter is adopted in the transfer alignment (TA) which is realized by the Velocity and Attitude Matching, when the disturbances in measurements are complete unknown. The performance of H∞ filter is compared with kalman filter. The simulation results show both that H∞ filter and kalman filter all are effective and kalman filter is more accurate than H∞ filter when system noise and measurement noise are white noise. But H∞ filter is more accurate than kalman filter when system noise and measurement noise are color noise. H∞ filter is an effective estimation method because H∞ filter is more suitable to engineering practice than kalman filter.

Analysis on the Nondestructive Testing Method of Concrete Strength

2014 ◽  
Vol 578-579 ◽  
pp. 987-990
Author(s):  
Jun Bin Gu
Keyword(s):  
Ultrasonic Velocity ◽  
Concrete Beam ◽  
Ultrasonic Method ◽  
Concrete Strength ◽  
Engineering Practice ◽  
Propagation Time ◽  
Ultrasound Propagation ◽  
Preliminary Study ◽  
Nondestructive Testing Method ◽  
Better Than

Preliminary study the damage of concrete beam by the ultrasonic-rebound method.The contents of the ultrasonic-rebound method are shown below: the concrete rebound value was determined by Rebound method and the ultrasound propagation time in concrete beam was determined by ultrasonic meter to calculate the ultrasonic velocity value in concrete, finally based on the concrete rebound value and the ultrasonic velocity value to confirm the strength of concrete beam.Because of a single rebounding or ultrasonic method is limit in theory and application, and lead to the defect in the application. But the ultrasonic-rebound synthetic method is much better than the above two methods respectively, and it improves the testing precision to apply to the engineering practice.

Sign in / Sign up

Export Citation Format

Share Document