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By the powder metallurgy, as well as subsequent forging and annealing processes, a series of W-3Re-HfC (WRH) composites were fabricated successively. Microstructure and performance of WRH composites were investigated comparatively. It is found that the sintered, forged and annealed WRH composites are consistently made up of W-Re matrix, HfO 2 and HfC second phase particles. The larger HfO 2 particle is derived from the oxidation of HfH 2 powder, playing an important role in purifying grain boundary and refining grain of matrix. The smaller HfC particle inside W-Re grains has a dispersion reinforcement effect. The forged WRH composites can obtain the highest relative density (99.9%), the micro-hardness (534.1 HV) and ultimate tensile strength (758 MPa), which is ascribed to the refinement of grains and dispersion strengthening. Although the performance of annealed WRH composites has a slight drop, an excellent interfacial matching between second phase particles and W-Re matrix can be produced, which facilitates to gain a better interfacial strength and homogenized microstructure. • Composites are composed of W-Re matrix, HfO 2 and HfC second phase particles. • The HfO 2 particle can effectively purify and pin the grain boundary. • Composites after forging can obtain superior micro-hardness and tensile strength. • Composites annealed at 1700 °C can yield an excellent interface strength. [ABSTRACT FROM AUTHOR]

• Six PCFT columns with internal energy dissipation bars were cyclically tested. • UHPC bedding layer and steel tube can ensure the larger ductility of PCFT columns. • The effects of initial PT force and ED bars on PCFT columns are identified. • The PCFT column is a minimal-damage precast structure with superior seismic behavior. In this paper, a promising construction option, which combines the concrete filled steel tubular (CFT) column and the self-centering rocking system, is introduced and its seismic behavior is experimentally investigated. In this hybrid system, named as post-tensioned concrete filled steel tubular (PCFT) column, the unbonded post-tensioned (PT) tendons and energy dissipation (ED) devices are employed to provide recentering and ED properties, respectively. The steel tube acts as a protective jacket, stay-in-place formwork, and transverse reinforcement. Six PCFT columns with different amounts of initial PT force and ED bars were tested. All columns failed due to the fracture of ED bars and the crushing of mortar bed which though was cast from ultra-high performance concrete (UHPC). The column shafts of specimens suffered little damage after testing. The amount of ED bars greatly affected the self-centering capacity and ED capacity of the PCFT columns when the ratio of ED bars was less than 1.2%. Beyond this ratio, its effect was negligible. Additionally, increasing initial PT force made only a little difference to the load-carrying capacity but significantly enhanced the self-centering capacity of the column. [ABSTRACT FROM AUTHOR]

• A novel cold-formed thin-walled steel beam-column joint entirely using self-tapping screws. • Influence of different connection modes on static load carrying effect. • Seismic behavior of H-section beam-square steel column joints connected by self-tapping screws. • The calculation method for yielding moment strength based on the improved component method. This paper proposes a novel thin-walled steel beam-column joint entirely using self-tapping screws. Compared to bolted and welded connections, its advantages of easy construction, low precision requirements, and fast construction are suitable for low-rise steel structures. Four full-scale H-section beam-square steel column joints connected by self-tapping screws were tested and the force transfer mechanism was investigated. Three of the specimens were loaded monotonically at the beam ends. The effects of the L-shaped connecting plate thickness and the arrangement of stiffening ribs on the bending performance of the joints are analyzed. Monotonic loading tests have demonstrated that the increased thickness and the arrangement of stiffening ribs enhance the common forces in the clusters of self-tapping screws, thereby increasing the bending stiffness of the joints. One of the specimens was tested with cyclic loads. The cyclic loading test revealed that the hysteretic curve of the self-tapping screws connection is relatively full, with high energy dissipation capacity and low degradation of strength and stiffness. Finally, the improved component method proposed the calculation method of bending resistance of self-tapping connection joints. The calculation accuracy is within 10 %, which can be used as a reference for the design of bending resistance. [ABSTRACT FROM AUTHOR]