Aspects of continuity in steel and composite frames

This thesis concerns the continuity in steel and composite frame and specifically the region of the connections. It reports on five main areas as follows: 1. Seven beam-to-beam connection tests were conducted to study the structural performance of composite end plate connections. Various parameters such as the types of connections, amount of reinforcement, beams sizes, and the degree of shear connection were investigated. The investigation confirmed a similar overall response of moment-rotation (M-φ) curves to beam-to-column tests and justified the restriction by current design codes of having partial shear connection in hogging moment region. A prediction method to estimate the initial stiffness of composite connection has also been proposed. 2. The effects of concrete encasement on structural response of end plate joints of slimfloor beams were investigated. Five specimens of beam-to-column connection of slimfloor were tested. Parameters such as end plate thickness and bolt sizes are included in the study. The results have shown that proper reinforcement and design are needed if the connections are to be considered as a composite joint. 3. Tests were carried out to improve the bond capacity of encased slimfloor. A total of six push-out tests each with different type of “shear enhancer” were performed. The load at initial slip is not greatly depend on the types of enhancer and there were indications that the resistance of the enhancer only became effective after slip, due to bond failure, had occurred. 4. As far as stability of composite beams in the negative moment region is concerned, local buckling has been identified as one of the problems. The action of reinforcement may reduce many hot-rolled section to be in Class 3. Studies were conducted on published data to explore the possibility of upgrading Class 3 to Class 1. The studies indicated that beams of Class 3 web showed the characteristics of beams with higher class if the connection was full strength. Many of the Class 3 beams used in composite beams can only be upgraded to Class 2 and not to Class 1. 5. A method applicable to the design of unbraced multi-storey frames to specified limits on horizontal sway deflection is proposed. Only simple calculation are required by the method and its application is illustrated by worked example