14 Oct 2025

Literature on the Load Distributions for Effects on Hydraulic Steel Structures: Notes on Existing Literature for Establishing LRFD Load Factors

Abstract: Previous to 1993 Hydraulic Steel Structures (HSS) were designed using Allowable Stress Design (ASD); modern design, has transitioned to Load and Resistance Factor Design (LRFD) method, which targets a probability of a limit state. To implement LRFD, an understanding of the probability distributions of the loads applied to the structure, the resistances of the components of the structure, and the approximate durations and overlapping of these loads must be determined. The loads applied to HSS are dissimilar to loads applied to buildings or roads, so existing distributions cannot be applied to this problem. Any attempts to implement LRFD without these distributions will result in designs that do not target the probability of reaching a limit state. The USACE has adapted LRFD load combinations and factors to encompass the different geometry, force and displacement conditions, and environments present in HSS. This work collects literature for load effects on HSS to determine either probabilistic distributions or what loads sufficiently unknown to necessitate new research. Because the loads the HSS are subject to are dissimilar to other designed structures, these load distributions cannot be taken from them directly. Loads considered are hydrodynamic, barge impacts, debris impacts, ice expansion, seismic, wind, and waves.

5 Jul 2023

Load and Resistance Factors from Reliability Analysis Probability of Unsatisfactory Performance (PUP) of Flood Mitigation, Batter Pile-Founded T-Walls Given a Target Reliability Index (𝛽)

Abstract: This technical report documents the research and development (R&D) study in support of the development of a combined Load and Resistance Factor Design (LRFD) methodology that accommodates both geotechnical and structural design limit states for design of the US Army Corps of Engineers (USACE) batter pile-founded, reinforced concrete flood walls. Development of the required reliability and corresponding LRFD procedures has been progressing slowly in the geotechnical topic area as compared to those for structural limit state considerations, and therefore this has been the focus of this first-phase R&D effort. This R&D effort extends reliability procedures developed for other non-USACE structural systems, primarily bridges and buildings, for use in the design of batter pile-founded USACE flood walls. Because the foundation system includes batter piles under flood loading, the design procedure involves frame analysis with significant soil structure interaction. Three example batter pile-founded T-Wall flood structures on three different rivers have been examined considering 10 geotechnical and structural limit states. Numerical procedures have been extended to develop precise multiple limit state Reliability calculations and for complete LRFD analysis of the example batter pile-founded, T-Wall reinforced concrete, flood walls.

5 Aug 2022

SAGE-PEDD Theory Manual: Modeling Windblown Snow Deposition around Buildings

Abstract: Numerical modeling of snowdrifting is a useful tool for assessing the im-pact of building design on operations and facility maintenance. Here we outline the theory for the SAGE-PEDD snowdrift model that has applica-tion for determining snowdrift accumulation around buildings. This model uses the SAGE computational fluid dynamics code to determine the flow field in the computational domain. A particle entrainment, dis-persion, and deposition (PEDD) model is coupled to SAGE to simulate the movement and deposition of the snow within the computational do-main. The report also outlines areas of future development that upgrades to the SAGE-PEDD model should address.