The Timber-Precast UHPC Composite Connection

Abstract

This paper deals with the connection of timber beams and precast concrete slabs. The connection of timber and concrete has many advantages associated with the efficient use of both materials, not only in terms of their stress. Timber is a natural renewable material. It can be achieved some savings of volume of the concrete by its application and thereby also reducing of the environmental burden. By the combining of the timber and ultra-high performance concrete (UHPC), it can be designed very subtle, bearable, aesthetic and durable structures. The conventional timber-concrete composite structures are most often realized by joining of the timber beams and the cast in-situ reinforced concrete slabs. However, the cast in-situ slab is not very suitable for UHPC application and it has some structural disadvantages, in particular the need to protect the timber beams against moisture penetration from the fresh concrete mix, the need for formwork, etc. The prefabrication eliminates some disadvantages of the cast in-situ design, increases the quality of the structure and speeds up the construction process. In the case of the timber-concrete composite structures, the prefabrication has a positive impact on the reduction of the concrete shrinkage projections as the development of deflections and the redistribution of internal forces between the connected parts of the cross-section. Some special coupling elements must be used for connection in the case of precast slabs. This paper summarizes the research findings in the field of development of special coupling elements for composite timber-precast concrete structures. The development of the new coupling elements for pedestrian and cyclist timber-UHPC composite footbridges is presented.