Illersteg

Kempten
Illersteg

bridge construction, sustainability  Services

Birk Heilmeyer und Frenzel Architekten  Architect

Innovative circular material-hybrid bridge construction

Project

The Illersteg pedestrian bridge, designed to span 70 meters across the Iller River in Kempten, Germany adheres to the principles of the circular economy. The structure consists of prefabricated modular wooden segments, an efficient load-bearing steel structure, and a thin layer of carbon fiber-reinforced concrete as the bridge deck. The structure strategically utilizes its three key materials – steel, wood, and carbon reinforced concrete – according to their functional and performance characteristics. These materials are combined in such a way that facilitates maintenance, replacement, and recyclability at the end of the bridge’s life cycle.

Integral hybrid construction with an efficient load-bearing steel construction and prefabricated modular wooden segments

Structural Engineering / Bridge Construction
The Illersteg is designed as a slender, partially fixed timber-steel hybrid structure. The main load-bearing system is a partially fixed two-span continuous beam, featuring a central steel box girder with a support at mid-span and monolithic, moment-resistant connections to the abutments. The design of the main girder follows the bending moment distribution: the girder height, width, and the thickness of the flange plates vary according to the changing structural demands along its length. The bridge girder is supported on a central pier, resulting in economical spans of 29 and 39 meters. The cantilevered bridge deck is constructed in timber, consisting of a cross-laminated timber deck slab supported by glulam ribs. The integral construction approach ensures a durable structure with minimal maintenance requirements, eliminating the need for joints and maintenance-intensive bearings.

Project data

Client City of Kempten

Architect Birk Heilmeyer und Frenzel Architekten

Services bridge construction, sustainability