New construction and conversion of office and residential buildings in Basel


At the intersection of Leonhardsstrasse / Steinengraben in Basel, five old townhouses were replaced by a new superstructure with residential and office use on behalf of Helvetia Versicherungen AG and HRS AG.

The special challenges of this project undoubtedly include the different foundation levels, which had to be taken into account both in the structural concept and in the development of an efficient construction sequence:

Neighboring buildings with deeper foundations directly adjoin the project parcels on two sides. In these areas, the loads of the new structures will be transferred past the existing structures using micropiles so as not to overload the exterior walls of the adjacent buildings. The foundations of the corner building, which are located above the base of the excavation pit, were underpinned with a tied-back reinforced concrete wall.

The 8m high excavation pit at the Steinengraben was constructed directly on the old counter wall of the medieval Basel city wall. The exposure of this quarry stone wall, which was up to 1.5 m thick, was intensively supervised by archaeologists and secured layer by layer with a shotcrete shell and earth nails.

The services include:

all project phases of

> structural design of new building

> structural design conversion

> earthquake reinforcement

> excavation support with nail walls

> underpinning of existing buildings

> Foundation with micropiles

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  • Helvetia Versicherungen AG / HRS AG
  • Seismic safety & earthquake engineering
  • Structural engineering


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