EVALUATION OF PERFORMANCE OF FRAMED STRUCTURE UNDER DYNAMIC LOADING

This project deals with the design, fabrication, and experimental evaluation of a microcontroller-based harmonic shake table developed for studying the dynamic behaviour of framed structures under controlled vibration conditions. The primary objective of the work was to simulate harmonic ground motion in a laboratory environment and to analyse the response of a scaled structural model subjected to dynamic loading. The developed shake table consists of a rigid platform of size 0.5 m × 0.5 m supported on a guiding mechanism and driven by a 12 V DC motor arrangement. The motion of the shake table was controlled using an Arduino Nano microcontroller programmed through the Arduino IDE, enabling the generation of sinusoidal motion with controlled frequency and amplitude. The system was designed to be economical, compact, and suitable for academic and experimental studies in structural dynamics and earthquake engineering. The hardware configuration of the shake table included one Arduino Nano microcontroller, one 12 V DC motor coupled with a motor driver circuit, one relay module for motor control, one regulated power supply unit, and a rigid steel–wood composite platform assembly. The sensing system comprised one tri-axial accelerometer module, two piezoelectric vibration sensors installed at different levels of the frame, and one load cell integrated with a signal conditioning circuit for force measurement. A scaled-down framed structural model made of wood was fabricated and securely mounted on the shake table platform to represent a simplified multi-storey building frame. The experimental setup was instrumented with an accelerometer (ADXL/MPU6050) mounted at the top of the frame to measure acceleration response during vibration. Piezoelectric sensors were installed at critical locations of the structure to sense vibration-induced strain and stress variations, while a load cell was positioned at the base to measure dynamic forces transmitted between the shake table and the test specimen. All sensors were interfaced with the Arduino-based data acquisition system, and the recorded signals were monitored and visualized in real time using appropriate software. The experimental study involved subjecting the framed structure to harmonic excitation at different frequencies and amplitudes controlled through motor speed variation. For each test condition, the shake table was operated until steady-state motion was achieved, and the corresponding acceleration, vibration, and force responses were recorded. The experimental results showed that the shake table was capable of producing smooth and consistent harmonic motion throughout the test duration. The acceleration-time histories obtained from the accelerometer showed peak acceleration values in the range of 0.05 g to 0.35 g and clearly indicated periodic sinusoidal behaviour, confirming the effectiveness of the control system. As the excitation frequency increased, a noticeable increase in acceleration response of the structure was observed, demonstrating the frequency-dependent nature of structural response under dynamic loading. The piezoelectric sensor outputs revealed variations in vibration intensity and stress–strain behaviour of the framed structure with changing excitation conditions. At lower frequencies, the structural response remained relatively stable, whereas higher excitation frequencies resulted in amplified vibrations. Resonance behaviour was observed within a specific frequency range, where a significant increase in acceleration and vibration amplitude was recorded. The load cell data further confirmed an increase in dynamic force transfer at higher excitation levels, indicating greater energy input to the structure during resonance conditions. These observations are consistent with the fundamental principles of structural dynamics and validate the experimental approach adopted in the study. The overall performance of the developed shake table demonstrated satisfactory reliability and repeatability of results. The system successfully replicated harmonic ground motion with a maximum table displacement of approximately 10 mm and enabled detailed observation of dynamic characteristics such as acceleration response, vibration patterns, damping effects, and resonance behaviour of the framed structure. The results confirm that the developed shake table setup is suitable for educational and experimental applications related to vibration analysis, structural response evaluation, and preliminary earthquake simulation studies. The project highlights the potential of low-cost, Arduino-based shake table systems as effective tools for laboratory-scale research and learning in the field of civil and structural engineering.