Iron‐based shape memory alloy active assembly connectors for civil structures

The lack of suitable connectors for thin‐walled carbon concrete elements with their known resource and material saving properties still represents a major obstacle for practical application. On top, the on‐site installation remains a labor‐intensive task. To overcome this limitation, we report the development of an active assembly connector that enables simple and safe installation of carbon concrete façade elements and increases assembly efficiency. Moreover, the active assembly features permit an assembly without physical access to the connector, called blind assembly. Its concept is based on the recovery expansion of iron‐based shape memory alloys (Fe‐SMA). This paper presents material characteristics such as recovery stress and strain of the Fe‐SMA in compression. The connector concept uses an anchor rail that blocks the recovery extraction of a Fe‐SMA‐fastener to produce a stable, frictional and linear connection. Tensile tests show the impact of design parameters and high pull‐out forces with sufficient design. Also, ongoing long term tensile tests show small creep, so far. The anchor channels integrate well with carbon concrete façade panels. The heating concept with heating cartridges works well, even under cold winter conditions. Wind test results exceed requirements. Finally, a field test shows excellent installation results and proves the ease of assembly as well as the ability for blind assembly.