This issue of Structures and Buildings consists of four technical papers. The first paper, by Sheehan and Chan (2014), presents the response of hollow and concrete-filled circular tubes under cyclic axial loading. A test programme on hollow and concrete-filled circular tubes was conducted. The ductility, energy dissipation, tensile strength and compressive resistance of the circular tubes were investigated. It is shown that the presence of concrete in the tubes increased the number of cycles to failure in all test specimens, which in turn enhanced the total energy dissipation. It is also shown that the AISC (2002) guidelines for post-buckling resistance were excessively conservative, while the CSA (1994) allowance overestimated the capacity in this study.
The second paper, by Vidalis and Nethercot (2014), examines the issue of composite frames for progressive collapse. A step-by-step methodology to determine the most efficient and practically applicable changes was introduced, making it possible to redesign the composite frame so that it is sufficiently robust to cope with any sudden column removal scenario. The proposed methodology is capable of highlighting system weaknesses. The third paper, by Adhami et al. (2014), examines the detection of damage to structures through deformation in bending under the excitation of random forces using a crack index. The effect of the non-linear behaviour of affected structural members was investigated according to which damaged members can be identified by means of a crack index. Several bilinear stiffness reduction functions were assumed for the column stiffness coefficient and beam stiffness coefficient. The proposed damage identification method has been examined by a ‘closed-loop solution' for a six- and an eight-storey bending structure.
The fourth paper, by Setareh (2014), presents the evaluation and assessment of office floor vibrations. It is found that vibration duration based on a peak absolute frequency-weighted acceleration of more than 0·015 m/s2 provides consistent evaluations in terms of human reaction to vibration. The investigation also compares the provisions of various standards and design guides. In this study, it is shown that the use of ‘vibration dose value' provides a more consistent and less conservative outcome than other criteria.
