Representation of Soil-Foundation Systems and Its Application to Shaking Table Tests by Constructing a Mechanical Interface

2013 ◽  
Vol 29 (2) ◽  
pp. 547-571
Author(s):  
Masato Saitoh ◽  
Tomoya Saito ◽  
Toshifumi Hikima ◽  
Makoto Ozawa ◽  
Keiichi Imanishi
Keyword(s):  
Experimental Studies ◽  
Pile Group ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Soil Medium ◽  
Lumped Parameter ◽  
Mechanical Interface ◽  
Foundation Model ◽  
Soil Foundation ◽  
Impedance Functions

Experimental studies on the dynamic response of structures comprising soil-foundation systems require an appropriately constructed soil-foundation model below the superstructures in order to properly estimate structural responses. In most studies, applying a small scaling is necessary for constructing the entire structural system, since there is limited space on shaking tables. This constraint has been a hindrance in experimental studies. Thus this study proposes a mechanical interface (MI) that represents the impedance characteristics of a 3 × 5 pile group embedded in a layered soil medium. The MI is constructed on the basis of lumped parameter models with gyro-mass elements. This element is mechanically realized in the MI using a rotational mass in combination with coupling gears. The results show that the MI properly simulates the impedance functions with frequency-dependent oscillations, and shaking table tests using the MI for an inelastic structure are demonstrated.

Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

2021 ◽  
Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding
Keyword(s):  
Seismic Behavior ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Pile Group ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Shaking Table Tests ◽  
Pile Groups ◽  
Acceleration Response ◽  
Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

scholarly journals EXPERIMENTAL STUDIES OF PILE FOUNDATION GROUND BASE REINFORCED WITH HARD INCLUSIONS

2019 ◽  
Vol 10 (3) ◽  
pp. 5-15
Author(s):  
M. L Nuzhdin
Keyword(s):  
High Pressure ◽  
Pile Foundation ◽  
Experimental Studies ◽  
Pile Foundations ◽  
Foundation Model ◽  
Series Of Experiments ◽  
Bored Piles ◽  
Soil Foundation ◽  
High Pressure Injection ◽  
The Impact

Often in construction practice there is a need to strengthen the pile foundation of buildings and structures. The traditional methods include the implementation of additional, as a rule, bored piles with the subsequent erection of a grillage incorporating them into operation. Often, this work has to be done in the conditions of dense urban development, in cramped rooms of the basement, etc., which leads to significant technological difficulties. One of the alternative ways to strengthen pile foundations is the method of high-pressure group injection, which consists in injecting a movable cement-sand mortar into the soil under pressure that exceeds its structural strength. As a result, after its hardening, solid injection bodies are formed at the base, reinforcing the soil base. The article describes the results of experiments to assess the impact of the layout of hard inclusions on the deformability of the soil foundation of the pile foundation model. The experiments were carried out in a small soil tray, which was filled with medium-grained loose sand. The piles were modeled with metal rods, the pile grillage with a metal square stamp. The pile foundation model included 9 piles arranged in a square grid. As injection bodies, gravel grains of various sizes and shapes were used. The studies included 10 series of experiments (each experiment was repeated at least 3 times): the volume of the inclusions used, their sizes, the positioning step in the plan and in depth varied. As a result of the analysis of the performed experiments, conclusions were formulated regarding the purpose of the optimal layout of hard inclusions when strengthening the soil foundation of pile foundations by high-pressure injection of mobile cement-sand mixtures.

scholarly journals Seismic Earth Pressures of Retaining Wall from Large Shaking Table Tests

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Changwei Yang ◽  
Jian Jing Zhang ◽  
Qu Honglue ◽  
Bi Junwei ◽  
Liu Feicheng
Keyword(s):  
Wenchuan Earthquake ◽  
Retaining Wall ◽  
Time History ◽  
Earth Pressure ◽  
Shaking Table ◽  
Rock Foundation ◽  
Shaking Table Tests ◽  
The Wenchuan Earthquake ◽  
Earth Pressures ◽  
Soil Foundation

To ascertain seismic response of retaining wall in the Wenchuan earthquake, large shaking table tests are performed and an acceleration record is acted in 3 directions. In the tests, acceleration time history recorded at Wolong station in the Wenchuan earthquake is used to excite the model wall. Results from the tests show that the location of dynamic resultant earth pressure is 0.35–0.49 H from toe of the wall for road shoulder retaining wall on rock foundation, 0.33–0.42 H for embankment retaining wall on rock foundation, and 0.46–0.77 H for road shoulder retaining wall on soil foundation. Besides, dynamic earth pressure increases with the increase of ground shaking from 0.1 g to 0.9 g and the relationship is nonlinear. The distribution is closed to for PGA less than 0.4 g but larger for PGA larger than and equal to 0.4 g, especially on the soil foundation. After the comparison of measured earth pressures and theoretical results by pseudodynamic method and pseudostatic method, results of the former are consistent with those of the shaking table test, but results of the latter method are smaller than measured.

Experimental Studies on Earthquake Response Behavior of Cylindrical Tanks

1987 ◽  
Vol 109 (1) ◽  
pp. 50-57 ◽  
Author(s):  
H. Zui ◽  
T. Shinke ◽  
A. Nishimura
Keyword(s):  
Seismic Behavior ◽  
Experimental Studies ◽  
Shaking Table ◽  
Earthquake Response ◽  
Test Results ◽  
Dynamic Tests ◽  
Shaking Table Tests ◽  
Liquid Storage ◽  
Cylindrical Tanks ◽  
Significant Factors

A series of dynamic tests for the seismic behavior of ground-supported liquid storage tanks are evaluated and compared with previous theoretical studies. Two model tanks were subjected to shaking table tests with particular attention to the influence of base fixity and geometric imperfections in the tank walls. Test results support numerical calculations which show that base fixity conditions strongly influence the seismic response of tanks. Although high radial accelerations are induced by the imperfections, they are not found to be significant factors in tank failure.

scholarly journals EXPERIMENTAL STUDIES OF A STEEL FRAME MODEL WITH AND WITHOUT BUCKLING-RESTRAINED BRACES

2016 ◽  
pp. 33-52 ◽  
Author(s):  
Héctor Guerrero Bobadilla ◽  
Tianjian Ji ◽  
José Alberto Escobar
Keyword(s):  
Free Vibration ◽  
White Noise ◽  
Experimental Studies ◽  
Steel Frame ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Frame Model ◽  
Seismic Input ◽  
Low Intensity ◽  
Vibration Tests

This paper presents comparative experimental studies of a five-storey steel-frame model at a scale of 1/10 with, and without, buckling-restrained braces (BRBs). The building model was subjected to free vibration tests and shaking table tests. The latter were conducted using low-intensity white noise and seismic input. From the free vibration tests and shaking table tests with low-intensity white noise, it was found that the BRBs contributed a significant amount of damping. This happened to the model even at low levels of vibration. The shaking table tests with seismic input were conducted using seven earthquake records, taken in the lakebed zone of Mexico City with seismic intensities from pga=0.1g to 0.25g. At an intensity of pga=0.1g, the results show that the model fitted with BRBs had a significantly smaller response than the bare model, in terms of displacement, inter-storey drift, floor velocity and floor acceleration. The higher intensities were only applied to the model fitted with BRBs. The results indicate that the model with BRBs was able to withstand about 2.5 times the seismic intensity of the bare model, in terms of lateral displacement, inter-storey drift and Arias Intensity, as a measure of the energy contents of the movement. At the end of the tests, all BRBs were removed and the model remained in its original undamaged state.

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