Beam-Column Method for Tieback Walls

Abstract

The beam-column method for the design of tieback walls is of intermediate complexity between the pressure diagram methods and the finite-element method. A set of recommended P-y, F-w, and Q-w curves are presented for the soil model, and the P-y method is described to simulate properly the construction sequence of excavation and tieback stressing. The recommended beam-column method is evaluated by comparing predictions with the measured behavior of four full-scale tieback walls in sand and in clay. The most influencing factors are identified through a parametric analysis and a comparison with four pressure diagram methods is presented. The beam-column method is a deflection-based method that satisfies the vertical, horizontal, and moment equilibrium of the wall. These significant and fundamental advantages over the pressure diagram methods make it a superior method, which should be used anytime the added complexity is warranted. The most severe limitation of the beam-column method is its inability to properly account for mass phenomena, namely, mass movement and downdrag. The most useful aspect of the beam-column method is its ability to give better bending moment profiles than the pressure diagram methods.