Identifying Failure Mechanisms of Typical I-Section Floodwalls

In 2018, Structural Integrity Associates, Inc. (SI) supported the United States Army Corp of Engineers (USACE) in the structural assessment of the concrete-to-steel connection in typical I-Section flood walls. A representative flood wall section is shown in Figure 1. This effort was part of a broader scope of work in which the USACE is revising their guidance for the design of flood and retaining walls, EM 1110-2-6066. The purpose of the structural assessment was to better understand the mechanics of load transfer from the reinforced concrete section to the embedded sheet pile. Three-dimensional finite element models of the connection were developed employing non-linear constitutive properties for the concrete, structural steel and reinforcement to achieve this goal. A total of nine different I-Wall configurations with varying wall geometry, sheet pile embedment depth, and connection details were analyzed. Hydrostatic load was applied incrementally to simulate the actual load distribution due to a rising water level.

FIGURE 1. Typical Flood Wall Section

ANACAP, SI’s proprietary concrete constitutive model, was used in the analyses to accurately predict the concrete behavior. Among other capabilities, the ANACAP model can capture multi-axial tensile cracking, compressive crushing with strain softening, and crack dependent shear stiffness. Figure 2 shows the evolution of a failure mechanism through the Loadconnection in one of the analyses as the hydrostatic load (i.e. water level) is increased. These results, along with additional variational studies, identified the typical failure mechanisms and limiting capacities of the embedded sheet pile connection, as well as providing assessments on the efficacy of retrofit measures and new connection design details.

FIGURE 2. Crack Propagation (shown in grey) with Increasing Hydrostatic Load

Please contact Dan Parker, PE if you are interested in learning more about ANACAP or how SI might help you in the evaluation of civil infrastructure.

Contact Form