UFC Comprehensive General Dry Dock Seismic Analysis Methodology

Abstract: To address extreme events changes, maintain mission readiness, and support the Navy’s future needs, NAVFAC is implementing seismic improvements at existing dry docks and incorporating seismic upgrades in design of new dry docks. For effective and efficient execution of this program, NAVFAC developed a standardized and comprehensive general dry dock seismic analysis methodology in high and low seismic regions. The purpose is to develop a basic methodology for the following scenarios: 1) relieved dry dock in high seismic region, 2) relieved dry dock in low seismic region, 3) gravity dry dock in high seismic region, and 4) gravity dry dock in low seismic region. The methodology is applied to existing and new dry docks with an emphasis on creating a template for reducing dry dock seismic analysis resources, thus saving time, costs, and labor. The outcome of this effort is to revise/update UFC 4-213-10 Graving Dry Docs to include seismic analytical methodologies and finalized criteria requirements. The final products will serve as planning, design and criteria documents for facility planners and designers. The new methodology for the dry docks includes geotechnical recommendations for structural design, modelling and analysis at a low and high seismic locations.

The geotechnical seismic evaluation parameters at low locations include a) inertial load factor; b) seismic earth pressure; c) hydrodynamic pressure; d) dry dock sliding resistance; and e) soil springs. The structural seismic evaluation parameters at low locations include a) demands; b) load combinations; and c) force-based seismic factors. The modelling and analysis seismic evaluation parameters at low locations include a) boundary conditions; b) 2-D cut analysis for forces; c) 2-D longitudinal analysis for displacement; d) 3-D analysis; e) consideration for piles; f) nonlinear time history analysis; g) gravity dry docks; and h) pressure relieved dry docks.

The geotechnical, structural, and modelling of seismic evaluation parameters at high locations follow the same methodology described above. However, additional seismic evaluation parameters for detailed analysis are required due to the higher seismic complexity of the location. These additional analysis types include a) simplified analysis; b) time history analysis; c) 2-D versus 3-D; d) computer analysis software for geotechnical, structural, etc. and e) constitutive models for soils.

How does this project / topic contribute to the advancement of the industry and profession?: The project is to revise/update the dry dock UFC to include seismic analytical methodologies and finalized criteria requirements. It advances the industry through its applicability to existing and new dry docks and creates a template for available dry dock methodology and seismic analysis resources. The final products will serve as planning, design and criteria documents for facility planners and designers.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: This methodology is innovative because it will be a single, ready reference document for dry docks located in low and high seismic area.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The most challenging aspect of methodology is providing recommend changes and consensus to standard code-based load factors that simplify design and promote resilient new or substantial dry dock structures facilities. To ensure success, the criteria preparation and revisions were unified in documents between the Army, Navy, Air Force and other Defense Agencies to the greatest extent possible unless justified by operational differences.

Who is the target audience for this paper?: The target audience for this paper is port practitioners, design engineers, facility planners, port authorities, decision-makers at all levels at ports and regulators, and code development and adoption personnel.