Flagshipstore Peek & Cloppenburg

Cologne

structural engineering, special structures Services

Renzo Piano Building Workshop Paris Architect

Department store with a doubly-curved shell structure made of timber strip girders and cable diagonals

Project

The new Peek and Cloppenburg department store in Cologne’s old town is a building of outstanding architectural quality. The building is divided into two wings, one with a rectangular layout and an east wing enclosed by a free-form self-supporting shell. This lightweight and finely detailed shell posed significant structural challenges, leading to the development of numerous details, including the innovative timber-strip shear connections made of cast steel.

Self-supporting, resource-efficient shell structure with a novel, reversible timber lamella connectors

SHELL DESIGN

The free-form shell features a shingled glass enclosure supported by innovative wooden strip girders and tubular steel profiles. The structural shell behavior is achieved by the addition of pre-tensioned cable diagonals within the rectangular framework of the vertical strip girders and horizontal steel tubes. The sixty-six girders are made of Siberian larch lamellae which are coupled by local shear connections from cast steel. The number of gluelam strips varies according to the stress distribution within the girder. The shell structure is supported by the reinforced concrete frame at the 4th floor, with girders spanning approximately 15 m to the ridge beam.

The shell construction was examined using various static models

Analysis of the structure

Analyse - Text ENG (300-550 Zeichen) Beschreibung der Berechnungen: FEM Modell, auf das Statische System eingehen; Thermische Berechnugnen, Photovoltaik Ertragsberechnugnen. The shell was analyzed using various structural models, differing in detail throughout the planning process. The geometrically non-linear calculations of the overall structure were carried out on a model in which the separated timber lamellae girders were represented in simplified form with an equivalent cross section. In addition to the usual loads from dead weight, snow, and temperature variations, wind study results and the interaction between the shell and the concrete base structure were considered. Through intensive construction stage analysis, the pre-tensioning forces of the cables, beam camber, and temporary support requirements were determined. The construction stage effects were back-calculated from the desired prestressing state in final service condition, removing elements and loading to match the erection sequence. Glass panels were erected on the fully pre-tensioned structure in some areas in order to achieve the required service condition.