is study assessed the mechanical properties and durability of latex-modified fiber-reinforced segment concrete (polyolefinbased macrosynthetic fibers and hybrid fiber-macrosynthetic fiber and polypropylene fiber) for a tunnel liner application. e tested macrosynthetic fiber-reinforced concrete has a better strength than steel fiber-reinforced concrete. e tested concrete with blast furnace slag has a higher chloride ion penetration resistance (less permeable), but its compressive and flexural strengths can be reduced with blast furnace slag content increase. Also, the hybrid fiber-reinforced concrete has higher compressive strength, flexural strength, chloride ion water permeability resistance, impact resistance, and abrasion resistance than the macrosynthetic fiber-reinforced concrete. e modified fiber improved the performance of concrete, and the hybrid fiber was found to control the formation of micro-and macrocracks more effectively. erefore, overall performance of the hybrid fiber-reinforced concrete was found superior to the other fiber-reinforced concrete mixes tested for this study. e test results also indicated that macrosynthetic fiber could replace the steel fiber as a concrete reinforcement.

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is study evaluated the performance of latex-modified fiber-reinforced concrete (RC) segments as a function of the substitution level of microsilica and type of reinforced fiber, to address the problem of corrosion of steel segments and steel-reinforced fiber segments, which are commonly used to shield tunnel-boring machine (TBM) tunnels in urban spaces. Our study compared macro synthetic, steel, and hybrid (macro synthetic fiber + polypropylene fiber) reinforcing fibers. e substitution levels of microsilica used were 0, 2, 4, and 6%. e target strengths were set at 40 and 60 MPa to test compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance. Testing of latex-modified and fiber-reinforced segment concrete showed that the compressive strength, flexural strength, and chloride ion penetration resistance increased with an increasing substitution level of microsilica. ese improvements were attributed to the densification of the concrete due to filling micropores with microsilica. Micro synthetic fiber was more effective in terms of improved compressive strength, flexural strength, and chloride ion penetration resistance than steel fiber. ese results were due to the higher number of micro synthetic fibers per unit volume compared with steel fiber, which reduced the void volume and suppressed the development of internal cracks. e optimal microsilica content and fiber volume fraction of micro synthetic fiber were 6% and 1%, respectively. To evaluate the effects of the selected mixtures and hybrid fibers simultaneously, other mixing variables were fixed and a hybrid fiber mixture (combination of macro synthetic fibers and polypropylene fibers) was used. e hybrid fiber mixture produced better compressive strength, flexural strength, chloride ion penetration resistance, and impact resistance than the micro synthetic fibers.

In this study, a number of fibre-reinforced concrete (FRC) cylinders, beams and dog-bone-shaped specimens were fabricated and tested under static loading conditions. The primary variables of the investigation were the fibre type (amorphous metallic fibres and steel fibres), water/cement (w/c) ratio (0·6 and 0·45) and fibre volume content (0–0·75%). With a lower w/c ratio, the compressive strength, elastic modulus, flexural strength and tensile strength increased, whereas the fracture energy decreased regardless of the fibre type or content. Compared with FRC with amorphous metallic fibres, FRC with hooked-end steel fibres exhibited much higher flexural toughness, residual strength and fracture energy, but showed lower compressive toughness and strain capacity. The volume content of amorphous metallic fibres had a pronounced effect on the flexural and tensile behaviours – higher fibre contents led to higher strength, deflection capacity, toughness and fracture energy because of the improvement of the fibre bridging capacity – whereas it had an insignificant influence on compressive strength and elastic modulus.

The numerical analysis was conducted to evaluate the behavior of slab-column connection subjected to blast loads using LS-DYNA. The typical form of slab-interior column connection for analysis was considered as a reference specimen and the drop panel slab-interior column was designed to verify the effects of drop panel. The slab-column connections, which were composed of interior, edge and corner column, were additionally analyzed to compare their confinement effects of specimens. Analysis results were contained the failure shape of connection, behavior of member and so on. From the results, the blast-resistant capacities of slab-column connection would be enhanced by reinforcing the drop panel. In addition, the performance of connections could be improved, when the confinement effects were enhanced.