Factors Influencing Transient Response of Shallow Strip Footing on Granular Soil Subjected to Vertical Pulse Load

Abstract

The structures located near seashore and industrial areas, basically apart from static loads are subjected to dynamic loads in the form of natural wind, storm loads, and machine vibrations. Uncertainty in the time of occurrence is something that makes these dynamic loads dangerous. Normally before the arrival of dynamic load, the foundation remains in a stable (steady) state, the state which is distorted with a sudden change in loading, putting the foundation in a trauma state. In an attempt to observe the transient response, the present study uses a numerical technique based on Finite Element Method (FEM) to model a footing-soil interface system following the concept of Beam on Nonlinear Winkler Foundation (BNWF) to minutely observe the transient response of a strip footing, i.e., the settlement due to first load cycle. Significant amount of influencing parameters including four intensities of static load, three depths of embedment of footing, three intensities of cyclic load, and three different relative densities of sand have been considered to find out the settlement of the footing. The results obtained from the numerical model, created and analyzed by numerical programming tool OpenSees suggest that the transient settlement is significantly affected by soil, footing, and loading characteristics with the allowable static load being the most dominant factor. An empirical expression is also developed to estimate the settlement of strip footing due to first load cycle.