Case Studies on Response of Laterally Loaded Nonlinear Piles

Abstract

Closed-form solutions for laterally loaded free and fixed-head piles in elastic-plastic media have been developed and implemented into a spreadsheet program called GASLFP. Underpinned by a generic limiting force profile (LFP), the solutions offer an expeditious and sufficiently accurate method for predicting response of lateral piles. They also allow parameters to be deduced using measured pile response, as is evident in the study to date on ~70 test (elastic) piles. The solutions also well capture the impact of structure nonlinearity of pile body by employing reduced pile bending stiffness (E_pI_p). The law of the reduction in E_pI_p, however, needs to be verified. In this paper, the solutions are utilised to examine the response of four test-piles exhibiting structural nonlinearity. For each nonlinear concrete pile, the shear modulus of soil and the three parameters (of N_g, α_o and n) for constructing the LFP were deduced first using elastic pile assumption; and subsequently the variations of flexural rigidity with bending moment, the cracking moment M_cr and the ultimate moment M_ult were back-figured against measured pile deflection. The study provides parameters for modelling nonlinear piles in sand and clay, and justification on using pertinent expressions.