Design and simulation of hydraulic shaking table

Recent industrial progress and computational technology made it possible to construct more complex structures. Vibration of these structures due to seismic strength must be measured and proved to prevent them from damage when they are subjected to earthquake. However, the accuracy of estimating the effect of vibrating structures is limited by the mathematical models, which are normally simplified from the actual complex structures. Due to this problem, a study on the development of shaking table is proposed. The main purpose of this study is to obtain the design specifications for a 1-axis (horizontal) hydraulic shaking table with medium loading, which can function primarily as an earthquake simulator and a dynamic structural testing apparatus. The project employs a three stage electrohydraulic servovalve, actuator system complete with hydraulic system as the power and drive unit. Mathematical model for closed loop control experimentation was presented and used to investigate the influence of various parameters on the overall system. The investigation includes the study on the effect of controller gain setting (for PD and AFC), disturbances and system stability. Time domain analysis using computer simulation was conducted to explain and predict the system’s response. Comparison between PD and PD-AFC controllers was done and it was found that latter PD-AFC fulfills the performance and robustness specifications for this project. Other design outcome that limits the change of disturbances on the system was also identified and taken as the framework for real world. This suggests that the next stage in implementation of the designed system can be made for the purpose of an earthquake simulator, since it works very well especially at low frequency level of shakin

UJI PERFORMANCE MEJA GETAR SATU DERAJAT KEBEBASAN DENGAN METODE STFT

In this research, it has been constructed a prototype of vertical shaking table, then its performance is tested and analyzed using the vibration signal processing. From this vibration signal can be acquainted the response of shaking table. In theoretical, a degree of freedom of vertical shaking table will have a perfectly stationary signal at all times of measuring, in the other side in experimental, the response of this shaking table has some frequencies. When this signal is processed by using Fast Fourier Transform or FFT, it will result the frequency spectrum which appear like a stationary signal at all times of measuring, so the time of vibration in time domain that will be undetected. To overcome the lack of FFT method, the vibration signal can be analyzed by using the Short Time Fourier Transform or STFT method. The results of this method can be viewed in spectrogram. By using this method, the vibration of shaking table can be depicted that occur at certain time

Detail design, building and commissioning of tall building structural models for experimental shaking table tests

Copyright © 2015 John Wiley & Sons, Ltd. Summary In the areas of seismic engineering, shaking table tests are powerful methods for assessing the seismic capacity of buildings. Since the size and capacity of existing shaking tables are limited, using scale structural models seems to be necessary. In recent years, many experimental studies have been performed using shaking table tests to determine seismic response of structural models subjected to various earthquake records. However, none of the past research works discussed practical procedure for creating the physical model. Therefore, in this study, a comprehensive procedure for design, building and commissioning of scale tall building structural models has been developed and presented for practical applications in shaking table test programmes. To validate the structural model, shaking table tests and numerical time history dynamic analyses were performed under the influence of different scaled earthquake acceleration records. Comparing the numerical predictions and experimental values of maximum lateral displacements, it became apparent that the numerical predictions and laboratory measurements are in a good agreement. As a result, the scale structural model can replicate the behaviour of real tall buildings with acceptable accuracy. It is concluded that the physical model is a valid and qualified model that can be employed for experimental shaking table tests

Experimental Investigations on Behaviour of Steel Structure Buildings

In this study, a comprehensive procedure for design, building and commissioning of scale steel structure building models has been developed and presented for practical applications in shaking table test programmes. To validate the model, shaking table tests and numerical time history dynamic analyses were performed under the influence of different scaled earthquake acceleration records. Comparing the numerical predictions and experimental values of maximum lateral displacements, it became apparent that the numerical predictions and laboratory measurements are in a good agreement. As a result, the scale structural model can replicate the behaviour of real steel structure buildings with acceptable accuracy. It is concluded that the physical model is a valid and qualified model which can be employed for experimental shaking table tests

Shaking Table System for Geotechnical Centrifuge

The shaking table system for geotechnical centrifuge, which can simulate sinusoidal and real seismic waves under a centrifugal force of 50 times earth gravity, is capable of providing significant data for the seismic design of structures. The shaking table can accommodate test specimens up to 250kg under 50G condition, so it can be used to perform various types of ground shaking tests

Design and Performance of a Single Axis Shake Table and a Laminar Soil Container

Correct evaluation of shear modulus and damping characteristics in soils under dynamic loading is one of the most important topics in geotechnical engineering. Shaking tables are used for physical modelling in earthquake geotechnical engineering and is key to the fundamental understanding and practical application of soil behaviour. The shaking table test is realistic and clear when the response of geotechnical problems such as liquefaction, post-earthquake settlement, foundation response and soil-structure interaction and lateral earth pressure problems, during an earthquake is discussed. This paper describes various components of the uniaxial shaking table at university of Guilan, Iran. Also, the construction of the laminar shear box is described. A laminar shear box is a flexible container that can be placed on a shaking table to simulate vertical shear-wave propagation during earthquakes through a soil layer of finite thickness. Typical model tests on sandy soil conducted on the shaking table and the results obtained are also presented. Appropriate evaluation of shear modulus and damping characteristics of soils subjected to dynamic loading is key to accurate seismic response analysis and soil modelling programs. The estimated modulus reduction and damping ratio were compared to with Seed and Idriss’s benchmark curves

Comparison of similitude laws applied to multi-storey masonry structures with flexible diaphragms

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Journal of Earthquake Engineering on 2022, available online at: http://www.tandfonline.com/10.1080/13632469.2022.2040655.The present paper discusses similitude laws employed for the shaking-table tests of masonry structures with flexible diaphragms. Two tasks are tackled. First, the paper presents a literature review on similitude laws. The discussion focuses on Cauchy and Cauchy-Froude laws. Second, numerical analysis is performed to examine the accuracy and adequacy of the aforementioned two laws. Two previously performed shaking-table tests are taken advantage of as the case studies. The paper explores the ideal applications of similitude laws to the shaking table tests of masonry structures with flexible diaphragms by comparing the behaviour between full-scale prototypes and reduced-scale models.Peer ReviewedPostprint (author's final draft

Development of Dynamic Laboratory Platform for Earthquake Engineering Courses

Small-scale shaking table platforms are usually used in seismic engineering courses to study the structural dynamic behavior of small scale specimens and investigate innovative solutions, such as active and passive control systems. Furthermore, they are also useful to actively involve students in learning programs in higher education. This paper illustrates the development and the teaching effectiveness of a multimodular unidirectional platform to be used by students during dynamic and seismic courses within the Shaking Table Educational Program at the Politecnico di Torino. A unique feature of this platform is that the system was entirely developed by undergraduate students. The project was intended to create a shaking table for earthquake simulation that can measure the structural response using sensors located on a specimen, such as a building, a bridge, or any other type of reduced-scale system. Different types of dynamic tests can be reproduced, such as hybrid simulations and pseudodynamic tests. A survey demonstrates the effectiveness of the laboratory experience during seismic engineering courses to improve student learning capabilities through a teaching activity that involves both theoretical and hands-on experience. Currently, the platform has been extended to accommodate bidirectional shaking table tests with the inclusion of augmented reality tools that allow exploring the response of human behavior during a pedestrian evacuation

Artificial table testing dynamically adaptive systems

Dynamically Adaptive Systems (DAS) are systems that modify their behavior and structure in response to changes in their surrounding environment. Critical mission systems increasingly incorporate adaptation and response to the environment; examples include disaster relief and space exploration systems. These systems can be decomposed in two parts: the adaptation policy that specifies how the system must react according to the environmental changes and the set of possible variants to reconfigure the system. A major challenge for testing these systems is the combinatorial explosions of variants and envi-ronment conditions to which the system must react. In this paper we focus on testing the adaption policy and propose a strategy for the selection of envi-ronmental variations that can reveal faults in the policy. Artificial Shaking Table Testing (ASTT) is a strategy inspired by shaking table testing (STT), a technique widely used in civil engineering to evaluate building's structural re-sistance to seismic events. ASTT makes use of artificial earthquakes that simu-late violent changes in the environmental conditions and stresses the system adaptation capability. We model the generation of artificial earthquakes as a search problem in which the goal is to optimize different types of envi-ronmental variations