Laing O’Rourke (LOR) have developed and patented a novel form of connection between precast
concrete panels utilising lapped headed bars, known as the “E6 joint”. Headed reinforcement bars
protrude from adjacent faces of precast lightweight concrete panels, such that a reduced lap length can
be used in the cast-in-situ joint region, thereby decreasing the joint width, when compared to straight
bar lap splices. Confining reinforcement in the form of vertical shear studs and transverse bars is also
installed in the joint. The aim of this research, funded by LOR, is to study the mechanical behaviour
of this novel form of connection, at the serviceability and ultimate limit states, by means of numerical
analysis, experimental testing and reliability analysis. The experimental results are used to validate a
three dimensional non-linear finite element (NLFEA) model of the joint. A strut-and-tie model (STM)
developed by LOR and reviewed by Arup, is used to determine the E6 design joint strength. Analysis
shows that the STM gives conservative results compared with numerical and experimental results
whilst not fully capturing the observed joint behaviour. More refined alternative design approaches
will be considered to overcome these shortcomings. Improved understanding of joint behaviour will
enable the joint design to be optimised and facilitate the development of an improved simplified
design method. Furthermore, a more widespread use of this system would lead to improvements in
buildability, sustainability and health and safety in construction of concrete structures.