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

The lack of suitable connectors for thin-walled carbon concrete elements withtheir known resource and material saving properties still represents a majorobstacle for practical application. On top, the on-site installation remains alabor-intensive task. To overcome this limitation, we report the developmentof an active assembly connector that enables simple and safe installation ofcarbon concrete façade elements and increases assembly efficiency. Moreover,the active assembly features permit an assembly without physical access to theconnector, called blind assembly. Its concept is based on the recovery expan-sion of iron-based shape memory alloys (Fe-SMA). This paper presents mate-rial characteristics such as recovery stress and strain of the Fe-SMA incompression. The connector concept uses an anchor rail that blocks the recov-ery extraction of a Fe-SMA-fastener to produce a stable, frictional and linearconnection. Tensile tests show the impact of design parameters and high pull-out forces with sufficient design. Also, ongoing long term tensile tests showsmall creep, so far. The anchor channels integrate well with carbon concretefaçade panels. The heating concept with heating cartridges works well, evenunder cold winter conditions. Wind test results exceed requirements. Finally, afield test shows excellent installation results and proves the ease of assemblyas well as the ability for blind assembly.