Structus Base: Safe load transfer in mass timber construction

Created on: 14 September 2026

Structus Base: The column base solution for modern mass timber structures

Mass timber buildings are becoming taller and more demanding. Timber columns made of glued laminated timber (glulam) or laminated veneer lumber (LVL) play a key role in transferring loads from the upper floors through the structure and into the foundation. Particular attention must therefore be paid to the connection between the timber column and the concrete foundation. At this interface, different building materials, high loads, and requirements for load-bearing capacity, durability, and moisture protection come together. Well-designed connection solutions at the column base are therefore essential to the performance of the overall structure.

Requirements for column base connections in multi-storey timber construction

Column base connections transfer loads from timber columns into the supporting structure below. In multi-storey timber construction in particular, high loads must be transferred through comparatively slender timber columns into the foundations. As the bearing area of the concrete foundation is often larger than the cross-section of the column, the column base connection plays a key role: it must accommodate the transition between the different cross-sections, distribute the loads in a controlled manner over a larger area, and prevent local stress concentrations in both the timber and the adjacent foundation. Depending on the structural design, horizontal shear forces must also be considered in addition to vertical compressive forces. At the same time, modern connection solutions are expected to provide high dimensional accuracy and efficient installation. Particularly in projects with a high degree of prefabrication, connections need to allow for precise positioning and support an efficient construction process.

In addition to load transfer, protection against moisture also plays an important role. Column base connections are often located at the interface between timber and mineral-based building materials, making measures necessary to reduce moisture exposure to the timber. Providing sufficient clearance from the foundation and adequately separating the components can help improve the durability of the structure. At the same time, the environmental conditions also affect the exposure of the steel components used. Fasteners and steel components should therefore be provided with suitable corrosion protection according to their intended use.

Structus Base as a connection solution between timber and concrete

For the construction of load-bearing column base connections in multi-storey timber construction, Eurotec offers Structus Base as a connection solution for connecting timber columns to a concrete substrate. The column base was developed as a further development of the Structus for use in modern timber engineering and is suitable for highly loaded timber columns. The design enables the transfer of compressive, tensile, and shear forces between the columns and the supporting structure below.

One of the key features of Structus Base is the design of its top plate. The inclined KonstruX fully threaded screws allow forces to be transferred in different directions. The five versions are designed for different column cross-sections, covering minimum cross-sections from 120 × 120 mm to 260 × 260 mm. This provides suitable sizes for different structural requirements. With a minimum height of 180 mm, the design ensures that the column and the sensitive end grain are protected from moisture during the construction phase.

Structus Base is made of galvanized S275 steel and is intended for use in Service Classes 1 and 2. Depending on the version, design compressive capacities of up to 1,400 kN can be achieved. The respective load-bearing capacities depend on the selected version and the underlying design conditions.

Structus Base

Normative basis: EN 1995-1-1:2025

The design of timber structures and their connections is carried out in accordance with the requirements of Eurocode 5 (EN 1995-1-1:2025). Structus Base is also designed for components that are designed and manufactured in accordance with this standard. The characteristic load-bearing capacities for the connection to timber specified in the product data sheet are based on the relevant design principles and consider, among other things, the properties of the timber components used. The design values are determined taking into account the modification factor k_mod and the relevant partial safety factor γM. The design of the connection to the concrete and the structural verification of the connected timber components must be carried out on a project specific basis.

Design and function

Structus Base consists of a top plate, a tubular section, and a base plate. Together, these three components form a continuous connection between the timber column and the concrete substrate. Depending on the product version, the dimensions of the plates as well as the diameter and length of the tubular section vary.

The timber column is connected to the top plate using the specified KonstruX ST fully threaded countersunk head screws. The screws are installed at an angle into the timber column, connecting it to the top plate. The Structus Base 1217 and 1616 models each use four 8 mm diameter screws. The larger 1813, 2213 and 2612 versions are each fastened with eight 10 mm diameter screws. The screw lengths are also matched to the respective version and range from 95 to 220 mm.

The forces transferred from the timber column are introduced into the top plate and then transferred through the tubular section to the base plate. The base plate forms the lower connection of Structus Base and is connected to the concrete substrate at four fixing points. Bolts or threaded rods can be used for this purpose together with the appropriate injection mortar. The suitable fixing method for each project must be determined through project-specific design.

The connection is also designed to allow for a step-by-step installation process. The top plate is first positioned on the timber column and fastened with the specified KonstruX screws. The column with the installed Structus Base is then positioned on the concrete substrate and the base plate is secured to the substrate. A major advantage of Structus Base is that no complex pre-fabrication or cutting work is required, allowing the connection to be installed easily either on site or in the factory. The design of the concrete connection and the structural verification of the connected timber components must be carried out on a project-specific basis independently of the design of Structus Base.

Applications

Structus Base is used wherever highly loaded timber columns need to be securely connected to a concrete substrate. Its main area of application is multi-storey timber construction, particularly in structures where high loads are transferred through the columns into the supporting structure below. Examples include multi-storey timber buildings and timber high-rise buildings with load-bearing columns made of glulam or other high-performance timber products.

In addition, the column base connection is suitable for other demanding structural applications in timber engineering. The different sizes allow it to be adapted to various column cross-sections and the requirements of the respective structural design. This makes it suitable for connecting timber columns to concrete in both multi-storey buildings and other highly loaded timber structures.

Conclusion

As buildings become taller and the demands placed on timber structures increase, well-designed connection details are becoming increasingly important. The column base connection forms the interface between the timber structure and the solid supporting structure and must therefore be carefully designed and executed.

Structus Base provides a solution that requires no extensive prefabrication work and is specifically designed to meet the requirements of modern timber structures. The different versions allow the connection to be adapted to the respective structural requirements, providing a reliable basis for column base connections in multi-storey timber construction. Particularly where connections are subject to high loads, a suitably dimensioned solution can help meet the structural requirements at the interface between timber and concrete.

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