Editorial

Abstract

2 3This is the second part of a two-part themed issue 'Composite (steel and concrete) structures -new developments and trends'. The aim of themed issue is to capture the state-of-the-art in the design of composite structures made from steel and concrete as there has been a boost in the use of composite structures (steel and concrete) worldwide. This second part features seven papers contributed by authors from different countries including Brazil, China, Greece, Iran, Hong Kong, Portugal, and United Kingdom. Authors shared their latest technical assessment on the next Eurocode 4, composite columns, composite connections, steel truss reinforced composite joints, shear connection by adhesion and interlocking & friction, sandwich panel infilled steel frames and composite steel frames with reinforced concrete infill.The first paper by Johnson (2018) presents an overview of the challenges faced in developing the next Eurocode 4 for composite structures. The paper initially describes the nature of comments received and recent information from research followed by a discussion of the priorities for inclusion in Eurocode 4. The main requests are centred on the needs to make it easier to use, to shorten it and to include much new material. This paper also presents examples of where removal of uncertainty and a few deletions would make EC4 more user-friendly. As for the new material, it indicates that priority should be given to the inclusion of provisions which fills gaps in current recommendations. Some requests for extension of scope have also been listed, with reasons given why some of them should not be accepted.The second paper by Zhu and Chan (2018) is a contribution in the field of the novel trend in composite structures, that is the association of steel or high strength steel with high strength concrete (around 100 MPa). The study experimentally and numerically evaluates the axial behaviour of concrete-filled steel tubes (CFST) with triangular, hexagonal and octagonal cross-sections and using high-strength concrete. The paper discusses the impact of cross-section shape on the load capacity and ductility of these CFST sections. The outcome of the experimental studies were also used in the assessment of existing design provisions in European, American and Chinese standards. The paper also presents finite-element models incorporating three existing concrete constitutive models and compares these results to the previously performed experiments. Finally, design approaches for CFST were also reviewed and assessed.The third paper by Rodrigues et al. (2018) evaluates the structural response of composite joints situated in hogging moment regions. An experimental program was proposed and was centred on the development of an alternative for the standard push out tests. In hogging moment regions the concrete slab is not under compression forces and it can lead to an extensive concrete cracking that may affect the actual structural joint response. An alternative setup (i.e. pull out tests) was developed and described to repre...