Lateral Load Resistance-Deflection of Piles Under Earthquake Excitation is Investigated in ITU Structural and Earthquake Engineering Laboratory

by Behlül Kula | Nov 26, 2021

The purpose of this project, in which the shaking table in the Structural and Earthquake Engineering Laboratory of our faculty is used, is to develop soil-pile resistance-deflection (p-y) relation especially for group piles in sands under seismic waves propagating through the soil from the bedrock. Unlike the current studies in the literature, the effect of nonlinear dynamic behavior of the soil during seismic waves propagating from the bedrock toward the surface on the p-y curves will be investigated and the p-y relationships will be developed for piles in a group (without the group effect) instead of using the p-y relations for single piles.

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Project Title: Development of lateral load resistance-deflection curves for piles in sands under earthquake excitation
Project Number: TUBİTAK-119M624
Project Coordinator: Assist. Prof. Dr. Esra Ece Bayat

Abstract: In recent years, the use of pile foundations in design becomes necessary with the rising demand in high-rise buildings with complex architectural design. Under the earthquake load, the soil-pile-superstructure system behaves together and the behavior of each component affects the other, which is defined as soil-structure interaction. (SSI). SSI analysis is crucial especially in some residential buildings, as well as in special structures such as high-rise structures, bridges, nuclear structures and hospitals. For the first time in history, the design of the pile foundations under earthquake load has been included in the new Turkish Earthquake Resistant Building Design Regulation (TBDY, 2019) and soil-structure interaction analysis has become mandatory for structures with pile foundations. The common trend in practice is to model the soil with springs instead of modeling it as 3D continuum. In this method, the behavior of soil-pile interface is represented by nonlinear springs defined at specified depths along the pile. The purpose of this project is to develop soil-pile resistance-deflection (p-y) relation especially for group piles in sands under seismic waves propagating through the soil from the bedrock. Unlike the current studies in the literature, the effect of nonlinear dynamic behavior of the soil during seismic waves propagating from the bedrock toward the surface on the p-y curves will be investigated and the p-y relationships will be developed for piles in a group (without the group effect) instead of using the p-y relations for single piles. For this purpose, numerical analyses and 1-g model tests are planned to be performed in parallel to understand the effect of the period of the building, the amplitude and the frequency (f) of the harmonic acceleration-time histories (amax), soil relative density (DR), the pile diameter and number of piles on the p-y relations. The p-y relations that will be explored in FLAC 3D software, will be validated in ACS SASSI (System for Analysis of Soil Structure Interaction) software program. The model experiments will be performed in a laminar box to be placed on a shaking table. Building models with different periods with 2x2 group piles embedded into the sand will be tested inside the laminar box, that will be excited under several harmonic displacement-time history records. As a result of these studies, soil-pile interaction correlations (p-y), which have the effect of nonlinear behavior of the soil, for piles without group effect under earthquake loads will be developed. In our country, there has not been conducted such a comprehensive research study on the soil-pile interaction, which is essential in the designs of these types of structures. Thus, with the project outputs, it is expected to reduce the dependence on international firms in the designs of these structures.

İTÜ Faculty of Civil Engineering

It can be accepted that the history of ITU Civil Engineering Faculty was commenced in 1727 by the establishment of Humbarahane during the era of Damat İbrahim Paşa. However, this attempt was to no avail due to the martyrization of the studwents of this school by the Janissaries.

In 1734, during the grand viziership of Topal Osman Paşa, classes related to Civil Engineering was being taught in Hendesehane, which was founded in Üsküdar. Similarly, this school was also closed after three years due to the opposition of the Janissaries. The reasons of the tragedy that occured in Battle of Chesma, 1770 were inadequacy of the ships and the ignorance of the Ottoman Navy.

Although the Atlantic Map (1513) and the Map of Europe and the Mediterranean Sea (1523) by Piri Reis were the leading pieces of the era, Ottoman viziers were so ignorant that they claimed it was impossible for the Russian Baltic Fleet to reach the Mediterranean Sea assuming that there were no sea connection. With the proposal from Gazi Hasan Paşa and Baron de Tott, Mühendishane-i Bahri-i Humayun was established during the time of Sultan Mustafa III, aiming to train naval construction engineers. Since Ottoman Empire did not have any engineering schools at the time, military engineering classes were taught by French engineers beginning from 1784. French lecturers had to return to their country in 1788 with the increasing suppression from Austria and Russia, which were unwilling for the development and thriving of Ottoman Empire. In 1759, during the Grand Viziership of Koca Ragıp Paşa, Humbarahane was reopened in Karaağaç, Haliç (Golden Horn) and continued to teach even though it was incompetent. In 1792, Lağımcı Ocağı and Humbaracı Ocağı (Guild of Sappers) were established.