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Rock anchor and high plinth foundations
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Two simply but effective foundation solutions are the rock anchor, designed for a wind park in Mexico and the high plinth solution for a wind farm in Chile. They are highly cost efficient, feasible and have proven to be very reliable in many projects.
Bilbao (ESP) – Special requests often demand tailormade solutions. But tailormade needs an high specialization and a lot of knowhow from the engineers in the specific field. In foundation design for wind turbine generator (WTG), this specific knowledge is not that common, except for CTE Wind International. Their senior engineers are often asked to find new design solutions. For this purpose, they resort to tried and tested instead of reinventing the wheel. Two simply but effective solutions are the rock anchor and the high plinth solution. They aren’t NEW solutions but are highly cost efficient, feasible and their reliability has been proved in many projects. This article features two project cases, among many others, where CTE Wind International designed rock-anchored foundations for a wind park in Mexico and a high plinth foundation for a wind farm in Chile.
Cost savings thanks to rock anchors
In Mexico, CTE Wind Ibérica was selected as WTG foundation designer by the EPC company. The project consisted of more than 20 concrete tower WTGs. The project analysis conducted by the foundation design expert has led to the recommendation to deploy two different solutions in order to optimize the costs of project. In fact, the soil conditions showed that over a third of the wind turbines were planned on rocky ground. Rather than equipping all wind turbine with standard slab foundations, CTE Wind’s engineering team decided together with the customer to implement rock anchors. This solution uses the rock mass as a WTG foundation. In that way the construction company is able take advantage of the earth crust instead of building a slab foundation. The costs for the reinforced concrete and the construction work can be saved. But this solution is specially challenging as the engineers have to adapt the foundation, with an interface, between the concrete towers and the rock anchors. Not to forget the special design work of these anchors that needs to be done. Finally, the client was impressed and satisfied about the result. But more important: the project costs were below the initial budget.
High plinth for extra height
In another case, CTE Wind was approached by a global construction company and explained the challenge for its project in Chile, with over 35 WTGs. The customer needed an hub height of 4 meters more to increase the energy production and ensure the yield and so its income. They weren’t totally satisfied with a complex solution by one of CTE Wind’s competitors. That is why the construction company asked CTE Wind to find a simple, reliable, feasible and cost-effective solution. That is how the high plinth foundation was chosen: a solution already tested and implemented in multiple projects in Europe. The idea of this foundation is to reach higher hub height with a high pedestal. The tower stands 3 to 6 meters above the «ground level», keeping the gravity foundation independent from the tower system. Ideally, the solution provides a longer anchor cage. CTE Wind’s engineering team designed the anchor cage for this project and determined the bolt length and steel quality. If needed, CTE Wind can also prepare detailed anchor cage drawings. After comparing the results of CTE Wind’s predesigns to the competitor’s solutions, the customer decided to go ahead with CTE Wind’s high plinth foundation. No difficulties in regards the construction have been reported. On the contrary, the Spanish expert of WTG foundation design was congratulated.
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
CTE Wind commissioned the Spanish University of Burgos to carry out a series of tests with the Soft-Spot™®. The structural tests are intended to prove once again if and how the resource-saving wind turbine foundation solution for “onshore” wind turbines works.
Burgos (ESP)/La Richardais (FRA) – The University of Burgos was entrusted with testing the patented Soft-Spot™® foundation solution from CTE Wind Civil Engineering for its functioning and safety at the end of 2021. The results of the test campaign, which ended at the end of May, confirmed what had already been demonstrated from many certification bodies worldwide and in various finite element models (FEM): The Soft-Spot™® works and is safe.
The Soft-Spot™® changes the stress distribution on the ground compared to a standard slab foundation. Due to central EPS soft layer, higher soil stresses are applied under the remaining ring.
As a result, a wind turbine with a Soft-Spot™® foundation will gap much later than a foundation without a soft layer, with the same foundation diameter. This increases the stability.
…use the Soft-Spot™® worldwide. The first project with the patented CTE Wind solution has been in place in 2019 in Thailand in a wind farm with 60 turbines. Each turbine has a hub height of 157 meters. Originally, a shallow foundation with 1,192 cubic meters of concrete and a diameter of 27.4 meters was planned.
But the excavation was not allowed to exceed more than 25 meters diagonally. Thanks to the soft layer under the foundation, the diameter could be reduced to 24.5 meters; minus 210 cubic meters of concrete (-18 percent) and 11 tons of reinforcing steel (-9 percent). The certifying body of DNV in Hamburg ensured that everything proceeded correctly and according to international standards during the design phase.
About CTE Wind Civil Engineering and the Soft-Spot™®
The Soft-Spot™® was developed by the French company CTE Wind Civil Engineering SAS. CTE Wind is an international engineering company specializing in the design and calculation of onshore foundations for wind turbines. The solution optimizes the existing and well-functioning system of shallow foundations by integrating known knowledge from structural engineering. Thus, a soft layer (EPS) is simply placed under the center of the foundation so that the forces of the wind turbine are transferred into the ground in a ring shape instead of onto the entire surface.
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
«To work with CTE Wind as designer was nice. The speed of response and reliability of the planning has been a winning experience for us.»
Arjan Louwerse from H4a Windenergie B.V.
Coöperatie Zuidenwind has poured the concrete for the foundation in Heibloem in the Netherlands and created the basis for the installation of their wind turbines. The foundation design and calculation for this project was done by CTE Wind Civil Engineering. The expert in foundation design WTG suggested their Soft-Spot® instead of a typical pile foundation.
Heibloem (NL) / La Richardais (FR) – The Netherlands soil consistsof unconsolidated, very young sediments. Due to the proximity of the low-lying part of the European continent, the basin of the North Sea, the bottom rarely rises higher than 30 m above sea level. In the areas along the coast (provinces of Groningen, Friesland, Noord-Holland, Zuid-Holland, Zeeland) the surface soil layers consist mainly of clay deposits. In the west of the Netherlands the clays are replaced by lowland moors (peat). To sum up: in the Netherlands, pile foundations are mandatory for wind turbines because of the concentrated forces occurring on little surface area. Except in Heibloem, where the ground is exceptionally stable. So good, in fact, that CTE Wind offered its resource-saving Soft-Spot® instead of the usual foundation.
The Soft-Spot® was developed by CTE Wind’s engineering team and is implemented in various countries around the world. «It was simply the most economical foundation we could choose », Arjan Louwerse from H4a Windenergie B.V. says. He is the project manager for Coöperatie Zuidenwind wind turbines. This foundation design optimizes the use of resources and helps to save up to 15 % of concrete and 2 to 5 % of reinforcement steel. In some cases what is even more important than the costs is the available space : with Soft-Spot® you need less surface for the foundation. This reduces the time and excavation costs. «The philosophy to reduce the costs of the Soft-Spot® was also a good point of discussion with our client. From the beginning we had a good feeling with the design», he explains.
In fact thanks to the new design the outer diameter of the foundation was 1.1m smaller compared to a typical foundation design. This resulted in a reduction of 11 % of concrete and 3 % of steel – or more precisely about 100m3 of reinforced concrete. «To work with CTE Wind as designer was nice. The speed of response and reliability of the planning has been a winning experience for us», Louwerse added. In spring 2020 the wind turbine will arrive together with the largest blades ever installed onshore in the Netherlands. (ctewind)
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
From 27 to 30 September 2022, Hamburg will become an energy hub for the world. For four days, at WindEnergy Hamburg everything at the trade show site will revolve around generating energy from wind and its exploitation.
CTE Wind partecipates in Hamburg with an own stand.
Leading business and union representatives provided diverse insights into all areas of the industry, with plenty of facts and figures. So as to cover the huge impending need for renewable energies, they highlighted the significance of personal exchange and knowledge transfer on an equal footing between industry, research institutions and policy
Alexander MARTIN CEO of CTE Wind International, along with the country Managers, engineering team and sales representatives of de CTE Wind offices worldwide will attend at the largest renewables conference dedicated to the wind energy market in Europe and all over the world. This is an excellent opportunity for interested companies to meet our sales team, learn more about CTE Wind’s expertise in civil engineering and foundations and discuss future collaborations..
Do not hesitate to contact us to organize a meeting.
See you soon in Hamburg.
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
Hamburg, Germany
September 27th to 30th, 2022
Research & Development
CTE Wind R&D and Consulting services are the first choice when it comes to foundation design regardless of the WTG-manufacturer, model, size, power or soil conditions. Thanks to internal R&D-Team with senior engineers, holding over 100 years of cumulated experience in the design of wind turbine foundations, nothing is impossible.
La Richardais (FRA) – In 2019 Developers worldwide have globally commissioned a little over 45GW of onshore wind turbines. According to Bloomberg New Energy Finance, the Danish firm Vestas remained this way the world’s leading wind turbine supplier, with Spanish-German wind engineering company Siemens Gamesa a strong second. Chinas manufacturer number one Goldwind was third in the rankings, while US-Leader GE Renewable Energy’s secured its fourth place. Together the top four manufacturers accounted for 55 percent of the market share.
100 years of cumulated experience
This statement applies more or less also to CTE Wind, which calculated, designed and evaluated about 5000 WTG-foundations in 2019 around the globe. Thanks to CTE Wind’s internal R&D, with senior engineers holding over 100 years of cumulated experience in the design of wind turbine foundations worldwide, new turbine models from the top manufacturers as well as less common WTG-models from smaller or local manufacturers are only a little challenge. CTE Wind engineering services lead to state-of-the-art foundation solutions for wind turbines. Regardless of whether it is a prototype, such as GE’s giant 12 MW Haliade X or smaller 1 MW machine, from German ENO or Dutch EWT.
Wooden tower
Also worth mentioning: the different types of towers for wind turbines. Concrete (hollow foundation) and steel towers are well known to CTE Wind. Both tower systems are suitable to be used alone or in combination. Even foundations with wooden towers were calculated and designed by CTE Wind in the past. The sum of all experiences made during the projects since 2003 is the reason why their engineering services in foundation design are the first choice for wind turbine manufacturers, wind park developers and EPC contractors worldwide.
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
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CTE Wind inaugurates its first North American office in Broomfield, Colorado. Senior Engineer Jomâa Ben-Hassine (PhD) will oversee the structural engineering and geotechnical projects in the US and Canada.
Broomfield, CO / La Richardais, France — CTE Wind International, a consultancy specialized in the structural design of onshore foundations for wind turbine generators (WTGs), is pleased to announce the official opening of its North American office – CTE WIND USA, Inc. – in Broomfield, Colorado (Denver metro area).
« The decision to open our new office in the State of Colorado is a sensible choice for us and for our clients, » says CTE Wind International CEO Alexander MARTIN. « Denver is near the geographic center of the country and is at the heart of the wind belt. From Denver International Airport, our office colleagues can reach most project sites in a few hours and can visit with our North American clients easily, » he explains.
The Colorado office is dedicated to supporting the needs of our North American clients. Our customers on both sides of the Atlantic asked CTE Wind for a North American presence. They can now benefit from the same responsiveness and know-how they have come to expect from the CTE Wind offices in France (HQ), Brazil, Poland, Portugal, Spain and in Asia.
Senior Engineer Jomâa Ben-Hassine (PhD, PE, P.Eng., ing.) who is leading the structural and geotechnical consultancy will serve as Director of Operations & Engineering in the US and Canada. Dr. Ben-Hassine is a civil engineer licensed in twenty US states and three Canadian provinces. He has accumulated over 30 years of practical experience in geotechnical engineering, structural engineering, foundation design, soil-structure interaction, reliability-based design, geohazard recognition and mitigation and risk assessment. He is active on several technical and standard development committees and has taken on leadership roles in multiple professional organizations (AWEA’s WTSC, ARESCA, IEC, and ASCE).
« We are very happy to have Jomâa Ben-Hassine on board of CTE Wind USA., » says MARTIN. « He brings in longstanding experience in wind and solar energy and knows the US and European standards and guidelines. North American EPC/BOP contractors and developers will benefit from the best of the two worlds, especially when it comes to bigger wind turbines above 4 MW with higher hub heights. »
CTE Wind Civil Engineering is an international engineering consulting firm specialized in the analysis and design of onshore wind turbine foundations. CTE Wind has been active in the wind energy sector since 2003. As of 2019, CTE Wind has designed, value-engineered or peer-reviewed foundations for over 17,500 turbines in 67 countries. CTE Wind is headquartered in France and has offices in Brazil, Poland, Portugal, Spain, USA and Asia.
The company is a subsidiary of the CTE Group, a consulting firm, specialized in building and civil engineering. The CTE Group was founded in 1965 and today is one of the leaders in the structural engineering sector.
If you want to learn more about CTE Wind International you can read more articles about projects and news in OUR-PROJECTS & OUR-NEWS – sections. For more Information about OUR-SERVICES please CONTACT US.
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