Monopiles (structural)
- Optimisation. Optimisation of monopiles for offshore wind farms whereby the minimum overall cost and/or weight of the structure are determined. This involves the investigation and examination of almost every aspect of monopile design, from overall layout to metallurgy of steel, etc. Matt Bristow is author of article “101 Ways of Making Monopile Savings” and “Methods for Optimisation for Monopile Design”.
- Grouted joints. Development of methodology for design of grouted joints from first principles and which predates the DNV guidelines (grouted joints designed to above methodology have been in service since 2003 and have not experienced any slippage, e.g. Arklow Bank).
- Sliding J-tubes. Design and development of external J-tube systems that do not rely on the use of divers and permit overdriving or underdriving of monopile. In addition system requires no J-tube hole in monopile, reduced monopile weights, and significantly reduced or elimination of corrosion on inside of monopile (as no cable seals to fail or ingress of aerated seawater). Read more here
Monopiles (geotechnical)
- Rock mass properties. State-of-the-art method for the determination of rock strength and stiffness parameters for weathered and fractured rock (based on Hoek Brown criteria and Geological Strength Index).
- Pile diameter effects. Development of what is known as ‘8-spring model’ for analysing large diameter piles, i.e. piles with length/diameter ratios L/D < 6. Pile diameter effects apply to large diameter piles where often additional soil resistances are available. For further details see Pile Diameter Effects.
- Cyclic loading of piles. Development of a new analytical method to determine the effects of cyclic loading on both axially loaded and laterally loaded piles. Methodology is based on the use of cyclic degradation curves and a new numerical procedure to quantify the effects of cyclic loading. Methodology allows the determination of cyclic p-y modifiers for any application, e.g. pile properties, cyclic load level, or soil layering, etc. Fully developed solution ready to use in the design office today and 5 years ahead of the current research in the industry. For further information and examples click here
Jacket structures
- Creation of innovative jacket configurations for minimal fatigue loads, minimal forces in braces, and minimum overall weight and cost of structure.
- Creation of innovative and alternative tubular connections (e.g. K-joints and X-joints) for minimal stress-concentration factor (SCF) and hence more efficient fatigue design.
- Selection and optimisation of various turbine tower to top of jacket connections for minimal fatigue loads, more efficient fatigue design, and hence minimum overall weight and cost of structure. Includes conical transitions, bespoke space-frame arrangements, and reinforced concrete interfaces, etc.
Gravity foundations
- Concept and design of gravity foundations for low bearing pressure and very low bearing pressure sites. Includes development of state-of-the-art two-layer soil theory for enhanced bearing capacity on thin but relatively weak top soil layers.
- Investigation into the installation of gravity foundations that do not require (costly) seabed preparation, including creation of various innovative self-levelling mechanisms.
- Investigation into truly self-installing foundations that neither rely on use of (costly) very heavy lift equipment or bespoke installation vessels (e.g. combination of semi-buoyant designs, low-lift installation vessels, controlled lowering to seabed, self-levelling mechanisms, and/or no seabed preparation).
Other geotechnical design tools
- Development of t-z springs (for axially loaded piles) based on hyperbolic shaped curves.
- Determination of p-y curves for sands and p-y curves for clays based on small-strain modulus (G0 or Gmax).
- Determination of epsilon-50 (parameter used to characterise stiffness of p-y curves for clay) from parametric equations, insitu site sites, and small-strain modulus.
- Use of elastic half-space theory to predict settlement and rotations of spread foundations, particularly on layered soils.
- Development of p-z spring concept for settlement of spread footings on soils.