The effect of dynamic load direction on the pile group performance for multi-story building in sandy soil

This study investigates the impact of the direction of dynamic load on the performance of pile groups supporting ten-story building by conducting a series of specially designed small model experiment on pile group foundation embedded in sandy soil profile. A 3*3 pile groups of 7D spacing were utilized as model of foundation, with soil models of 70% Dr. Shaking table device was utilized to simulated the Kobe earthquake motion. The seismic load was applied on the tested system in different horizontal angles (0°, 15°, 30° and 45°). The results show a significant rise in pile cap lateral displacement as seismic angle increase, reached to 9 times when increasing the horizontal seismic angle from 0° to 45°. The analysis further revealed there is an inverse correlation between the seismic load angle and the vertical displacement measured on the pile cap directly impacted by the seismic load, when increasing seismic angle from 0° to 15°, there is a 54% decrease in vertical movement. This pattern carries on reaches to 500% at a 45°. In conclusion, the findings showed that the greatest acceleration occurs at an angle of 30°, followed by 15°, 45°, and 0°. In addition, the acceleration at the pile cap is highest when compared to the measurements taken within the soil and the 10-story building for all four horizontal seismic angles.