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In this paper we present an investigation of the impact of cold-formed steel channel section columns when subjected to an axial impact by a rigid impactor. The work involves both the numerical simulations and experimental tests. The former was done by using nonlinear finite element analysis method and the latter was done by using drop hammer tests. In the present finite element analysis, material nonlinearity, strain rate effect, initial geometric imperfection, and interactions between the impactor and column are considered. It is shown that the impact deformation of the channel-section column under the axial impact of rigid impactor can be characterized initially by its axially compressive deformation, followed by the localized bending deformation in the region where the geometric imperfection is large. The validation of the numerical results using the drop hammer test results demonstrates the appropriateness of the numerical model developed in the paper. • It presents original experimental data of axial impact tests of CFS channel section columns. • FE analysis is provided to simulate axial impact tests of CFS channel section columns under different impact velocities. • Initial geometric imperfection of CFS columns and uses strain rate-dependent elstoplastic stress-strain equation. • The results show that impact velocity significantly affects the final residual deformation of columns. [ABSTRACT FROM AUTHOR]

• Light metal exoskeletons are used for integrated seismic-energy retrofit of existing RC buildings. • Three different solutions are applied to increase the seismic performances of an existing RC school buildings. • Seismic behaviour before and after interventions is investigated in the static non-linear field. • The comparisons among intervention techniques are made in terms of the seismic safety index provided by the Italian technical standard. • Local reinforcement interventions on RC school building columns are performed together with the applied exoskeletons to attain the minimum safety index required by the standard code for this building category. Italian built heritage is highly vulnerable due to old public and private buildings designed without recent seismic and energy regulations. In particular, school buildings represent a critical typology that should be retrofitted to guarantee safety and comfort to the users. In this framework, interventions from building outside able to avoid interruption of school activities should be required. A solution to solve this issue can be found in the retrofit solution with exoskeletons. In this scenario, the paper presents the comparison among three similar solutions of metal lightweight exoskeletons for the integrated seismic-energy retrofit of a RC school building assumed as a case study. The RC structure of the school is firstly modelled with a finite element software and then subjected to pushover analysis before and after retrofit interventions to assess the benefit of each exoskeleton solution. The comparisons among intervention techniques are made in terms of the seismic safety index (ζ E) provided by the Italian technical standard. The results show the more or less efficacy of the different inspected systems, even if integrative local interventions are needed to reach the minimum safety index (0.60) required for school buildings. As a conclusion, these novel light metal exoskeletons have proven to be efficient retrofitting systems for residential buildings or even for school buildings with regular façades and plan layouts. [ABSTRACT FROM AUTHOR]

Steel pallet racks (SPRs) are used in the industrial buildings, warehouses and superstores for storing a multitude of different kinds of goods. Because of changing needs over the years, it is often desirable that such installations be readily demountable and capable of reassembly. Therefore, the beam-to-column connections (BCCs) used in SPRs are boltless in nature. SPR BCCs govern the stability of the frame in the down-aisle direction. The design of SPR BCCs is one of the problems for designers that cannot be handled routinely within the existing design specifications available for bolted and welded connections. Moreover, the studies on the considerations necessary for the design and performance of SPR BCCs solely are rarely available. It is therefore, essential to bring to light the factors that play significant role to improve the design and performance of SPR BCCs. A critical review of the research performed over the last few decades into the global stability of SPR structures in the down-aisle direction only is presented in this paper. The information about the design methodologies and testing procedures defined in the literature and design codes as well as the factors governing the performance of boltless connections are identified. The major failure modes are highlighted. The characteristics of the main elements constituting SPRs are also succinctly discussed. Based on the findings, the limitations of current study are highlighted and future research areas are identified. [ABSTRACT FROM AUTHOR]

• A new type of SPSW structure is proposed. • The mechanical properties and failure modes of the specimens were analysed. • The design method of the shear capacity of buckling-restrained beam-only-connected SPSWs was proposed. In this paper, a new type of steel plate shear wall (SPSW) structure comprising square concrete-filled steel tube (CFST) boundary frame and infilled cold-formed steel (CFS) buckling-restrained beam-only-connected SPSWs is proposed. To study the lateral behaviour and failure modes of the buckling-restrained beam-only-connected SPSWs with square CFST frame, tests on a buckling-restrained beam-only-connected SPSW and a comparison specimen with unstiffened beam-only-connected SPSW with square CFST frame were conducted. The failure mode, hysteretic curve, shear capacity and energy dissipation capacity of the specimens under horizontal cyclic load were reported. The results showed that the two specimens had good lateral resistance and stiffness, which indicated that this structural system was a reliable SPSW structure. Besides, the arrangement of the CFS buckling-restraining strips could improve the seismic performance of beam-only-connected SPSWs. A total of 84 finite element (FE) models were developed and validated. Upon validation, the parametric analysis was carried out, and design method of the shear capacity of buckling-restrained beam-only-connected SPSWs was proposed. The results show that the newly developed design method is accurate and can better predict the yield capacity of CFS buckling-restrained beam-only-connected SPSWs. [ABSTRACT FROM AUTHOR]