A six-storey student accommodation block on Perth Road recently required a seismic foundation design approach that went well beyond standard bearing capacity checks. The underlying glacial till, though dense, showed interbedded sand lenses that could behave unpredictably under cyclic loading. In our experience, projects across Dundee’s varied geology — from the Tay floodplain to the Sidlaw foothills — demand site-specific ground response analysis rather than code-prescribed default values. Before finalising the foundation scheme, the team ran a MASW survey to map shear-wave velocity profiles down to 30 metres, which directly informed the design spectrum for the structure.
The key is understanding how Dundee’s glacial and fluvial deposits will behave under cyclic loading, not just static bearing capacity.
Process overview
Local context
The biggest risk we encounter in Dundee is the misinterpretation of the glacial till as a uniform material when it often contains discontinuous sand and gravel lenses. Those lenses can generate excess pore pressure during an earthquake, reducing effective stress and causing differential settlement. We counter this by running a phased investigation: first a desk study of BGS borehole logs, then probe holes with SPT every metre, followed by undisturbed sampling for cyclic triaxial testing. The cyclic triaxial test under undrained conditions with varying confining pressures replicates the stress path a foundation element would experience during a design earthquake, giving a realistic picture of strength loss.
Reference standards
BS EN 1998-1:2004 (Eurocode 8 – seismic design of structures), BS EN 1997-1:2004 (Eurocode 7 – geotechnical design), NEHRP Recommended Seismic Provisions (FEMA P-1050), BS 1377 (resonant column test method)
Additional services
Site-Specific Seismic Hazard Assessment
Probabilistic and deterministic seismic hazard analysis for Dundee sites, using UK hazard models and local fault data. Output includes uniform hazard spectra, magnitude-distance deaggregation, and design ground motions for serviceability and ultimate limit states.
Foundation Seismic Design & Detailing
Design of shallow and deep foundations for earthquake resistance, including ductility detailing, tie beams, and base isolation where needed. We verify performance via pushover analysis and nonlinear time-history simulations when required by the project.
Typical parameters
Quick answers
What is the difference between ductility detailing and capacity design in seismic foundations?
Ductility detailing ensures that connections and reinforcement can undergo inelastic deformation without brittle failure. Capacity design, on the other hand, forces the ductile failure mode to occur in a controlled location (e.g., the column base) while adjacent elements are over-designed to remain elastic. Both concepts are embedded in Eurocode 8 and applied to Dundee projects where ground shaking may exceed the elastic response.
How much does a seismic foundation design study cost in Dundee?
A full seismic foundation design study in Dundee typically ranges from £870 to £2,930, depending on the building size, site complexity, and number of boreholes. The cost covers the seismic hazard assessment, site response analysis, and foundation design calculations. For a straightforward three-storey block on competent till, expect the lower end; for a large structure on variable ground, the upper end applies.
When is a site-specific response analysis mandatory instead of using the UK national annex spectra?
A site-specific response analysis is mandatory when the soil profile does not match the idealised ground types in Eurocode 8 Table 3.1, or when the building falls into importance classes III or IV (e.g., hospitals, emergency centres). In Dundee, this often occurs where soft alluvium overlies stiff till, generating a deep impedance contrast that the standard spectrum cannot capture. We also recommend it for any structure exceeding 15 metres in height on ground class D or poorer.