Dimitrios at Deep Excavation LLC wrote this article a couple of months ago for his monthly newsletter. He contends that for multi-level braced excavations, the AASHTO LRFD code could produce unconservative results. From his article:
The currently adopted design methods for AASHTO (2010) LRFD appear to produce inconsistent and possibly unsafe designs for many multi-level braced excavations. Limit-equilibrium analyses combined with LRFD methods appear to severely underestimate benchmarked wall bending moments. For this reason, analyses in this paper suggest that limit-equilibrium methods should not be used to design the wall bending resistance for multi-level-braced excavations.