Perfect is the Enemy of Good: Criteria for Limiting Nonlinear Pushover Reanalysis

Abstract: Every new design project struggles with balancing condensed schedules and tight budgets with the reanalysis effort required to incorporate late design changes. This is especially true for engineers who have not yet grasped the age-old mantra that “perfect is the opposite of good,” treating every analysis as final instead of as a checkpoint in the design process. This issue has become more prominent in recent years as advanced structural analysis techniques, such as nonlinear pushover analyses, have become routine design tools. While these analyses offer valuable insights into the structural performance of piers and wharves subjected to dynamic environmental forces, they also result in significant cost and schedule impact when relied upon heavily during design development, rather than strictly as a confirmatory analysis.

This paper explores the effects of common design changes on structural behavior of pile-supported shoreline structures to understand when a reanalysis is warranted or required. We investigate criteria for distinguishing changes that do and do not require comprehensive reevaluation such as changes in substructure size and location, soil input parameters, changes in topside load distribution for operational considerations or future expansion, and changes in modal response when base shear amplification is required for topside structures. In this paper, we provide insight into establishing a reasonable amount of contingency throughout design development and offer strategies to determine if a reanalysis is appropriate at different stages of design. These considerations not only improve the engineering efficiency and schedule on future projects, but also provide engineers with tools to reduce costs by optimizing the frequency of analysis during the design and construction stages.

How does this project / topic contribute to the advancement of the industry and profession?: This topic provides designers and engineers with common examples of design changes that impact time-consuming analyses and offers strategies to determine when and if a reanalysis is appropriate. These considerations will provide engineers with tools to enhance overall efficiency throughout the life of the project and will help in the planning of future projects.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: Yes, we highlight advanced analysis techniques and common design changes that designers should consider before utilizing resources to perform additional analyses. The changes discussed are often driven by supplier and material selection, code-required analysis methods, and owner-requested modifications.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: Balancing the extent of reanalysis effort with design efficiency while maintaining code compliance, operational functionality, and client satisfaction.

Who is the target audience for this paper?: Engineers, designers, owners and operators.