Equivalent Cantilever Research Articles

Assessment on pile effective lengths and their effects on design—I. Assessment

Various methods for determining depths to fixity as required in an equivalent cantilever pile model, including the current practical method (LRFD method) and the proposed method with a comprehensive numerical procedure, are described and discussed. Suitability and applicability of the methods are carefully assessed with applications to steel H piles.

Validation of Design Recommendations for Integral‐Abutment Piles

Because integral‐abutment bridges decrease the initial and maintenance costs of bridges, they provide an attractive alternative for bridge designers. The objective of this project is to develop rational and experimentally verified design recommendations for piles in these bridges. Field testing consists of instrumenting two bridges in Iowa to monitor air and bridge temperatures, bridge displacements, and pile strains. Core samples are also collected to determine coefficients of thermal expansion for the two bridges. Design values for the coefficient of thermal expansion of concrete and revised temperature ranges for the deck and girders of steel and concrete bridges are recommended. A girder extension model is developed to predict the longitudinal bridge displacements caused by changing bridge temperatures. The pile is idealized as an equivalent cantilever. The frame model better predicts both the longitudinal displacement and weak‐axis pile strains. A lateral frame model is presented to predict the lateral motion of skewed bridges. Two alternatives for the pile design are reviewed: the first alternative, the more conservative, includes thermally induced stresses; the second neglects thermally induced stresses but allows for inelastic redistribution of forces.

3-D response of buildings to wind action

A mathematical model to predict the simultaneous along-wind, across-wind and torsional response of rectangular buildings to wind acting normally to a face is formulated. Wind loading is treated as a multiple stochastic stationary Gaussian process including mean wind forces and fluctuating forces due to atmospheric turbulence and wake excitation. The building is modelled as an equivalent cantilever beam with three degrees of freedom per floor. Methods of random vibrations are used to estimate the root mean square and peak values of the most relevant components of the dynamic response. The comparison between predicted wind loads and experimental data available in the literature demonstrates the reliability of the mathematical model of wind excitation, while the application of the numerical analysis to actual buildings indicates that the procedure presented herein represents a suitable methodology to analyse structural behaviour to wind action.

Dynamic response curves for vertically loaded floating pile foundations: Discussion

In recent years significant progress has been made in the dynamic analysis of pile foundations. The older methods of analysis were most often based on the concept of the equivalent cantilever, an approach that does not allow for any rational account of energy dissipation (damping), interaction of piles in a group, or a number of other factors. The more recent approaches consider the soil as a continuum and allow for dynamic soil-pile interaction, energy dissipation through propagation of elastic waves, and pile group effects. Kuhlemeyer's contribution belongs to the latter category; it aims at facilitating the design and is timely because there is an increased interest in pile dynamics prompted by the design of large compressor stations and other facilities. Because Kuhlemeyer's paper provides graphs recommended for practical application, some discussion may be useful.

Design of Machine Foundations on Piles

A practical method for the analysis of pile-supported foundations subjected to dynamic loadings is described. The method uses a single-degree-of-freedom mass-spring-dashpot model of a form similar to that used for shallow foundations to analyze the response of the actual system. The method of analysis uses the concept of an equivalent cantilever, which is a technique to simplify the soil-structure interaction problem, and allow the computation of equivalent spring constants in all modes of vibration. The method is demonstrated with an actual case history where computed and observed motions are compared.