BEAM-COLUMN METHOD FOR TIEBACK WALLS

The beam-column method for the design of tieback walls is of intermedi ate complexity between the pressure diagram methods and the finite-ele ment method (FEM). A set of recommended P-y, F-w, and Q-w curves are p resented for the soil model and the P-y path method is described to si mulate properly the construction sequence of excavation and tieback st ressing. The recommended beam-column method is evaluated by comparing predictions with the measured behavior of four full-scale tieback wall s in sand and in clay. The most influencing factors are identified thr ough a parametric analysis and a comparison with four pressure diagram methods is presented. The beam-column method is a deflection-based me thod that satisfies the vertical, horizontal, and moment equilibrium o f the wall. These significant and fundamental advantages over the pres sure diagram methods make it a superior method, which should be used a nytime the added complexity is warranted. The most severe limitation o f 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 momen t profiles than the pressure diagram methods.