Displacement incompatibility between reinforced concrete moment frames and precast flooring systems has been shown experimentally, and in historical earthquakes, to be an area of concern. Plastic hinge formation necessitates beam damage and the resulting elongation of the beam reduces the seating length of the floor, exacerbates the floor damage and induces unanticipated force distributions in the system. In severe cases this can lead to collapse.The slotted beam is a detail that protects the integrity of the floor diaphragm, respects the hierarchy of strengths intended by the designer and sustains less damage. The detail provides the same ductility and moment resistance as traditional details, whilst exhibiting improved structural performance. This is achieved with only a subtle change in the detailing and no increase in build cost. This paper briefly presents the development of the slotted beam in reinforced concrete. The design and construction of a large scale reinforced concrete slotted beam superassembly is described. The experimental method used to undertake biaxial quasi-static testing is introduced. Preliminary observations from the experiment are presented. It is shown that the reinforced concrete slotted beam is a viable replacement for the traditional monolithic detail. Extremely promising structural performance and significantly reduced damage compared to monolithic reinforced concrete details is presented.

This paper describes the development of the slotted beam detail. The design, construction, testing and results of two large experimental programs investigating the seismic performance of the slotted beam detail, described herein as Phase I and II, are presented.In Phase I a two-storey, two-by-one bay, reinforced concrete slotted beam superassembly was tested under quasi-static cyclic loading. The specimen was designed, constructed and erected to closely replicate New Zealand construction techniques for a typical multi-storey building, which enabled the practicality of the detail to be assessed. A demanding biaxial loading protocol was applied to enable performance assessment of the slotted beam connections. In addition, the threedimensional interactions between structural elements in the lateral load resisting system were examined.In Phase II five three-dimensional exterior beam-column subassemblies with floor slabs were tested under a similar regime to Phase I. Two subassemblies were directly extracted from the superassembly tested in Phase I and tested to determine the residual capacity of the subassemblies, following a large earthquake. The tests on the remaining three subassemblies investigated viable options for, and performance of, repair retrofit solutions for reinforced concrete slotted beam connections following large earthquakes. The retrofit solutions utilised tension-compression yielding, sliding friction and lead extrusion external energy dissipation devices. The tests also served to assess the performance of the replaceable dampers for new build applications.

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