Simplified 1-D modeling of duo-pile system subjected to lateral loads

Duo-pile (two piles connected by a beam) can be used as foundation system for elevated railways and highways. The design of foundation system for these types of structures is very critical with respect to lateral deflection which can affect serviceability and the stability of superstructure, as well. Duo-pile systems response can be estimated by three-dimensional (3-D) and as well one-dimensional (1-D) numerical (Finite element) modelling. Although 3-D models can simulate real scenario accurately but due to their sophisticated and time consuming nature 1-D models are very much in practice. In this study firstly, duo-pile behavior is studied from its 3-D response. Duo-pile system which can transfer moments in its longitudinal direction is much different from single pile response, hence, separate treatment for both transverse and longitudinal behavior of duo-pile system is to be given. Spring constants for beam and piles have been found out individually for using those in the combined duo-pile model. Spring constants for pile are proposed by considering the interactions prevailing in the system. A new type of interaction spring is introduced to capture couple effect. By integrating all the beam and pile springs, a simplified 1-D model for duo-pile system is proposed for both transverse and longitudinal response which can give approximate results with respect to 3-D modelling. By using the proposed model potential location of plastic hinges have been also found out.