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Changyuan Dai,Qingtian Su,Changyu Shao,Chunlei Zhang 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.2
The outer lanes and emergency lanes of the bridge deck of long-span bridges in which orthotropic steel deck is adopted were replaced with Ultra-High-Performance-Concrete (UHPC) composite deck to create a hybrid bridge deck system. A transverse connection detail was proposed to connect the two diff erent bridge deck forms. Static bending tests and theoretical analysis were conducted on the transverse connection detail to obtain failure modes, ultimate load-carrying capacity, crack resistance, and the collaborative bending performance under positive and negative moments. A calculation method for the ultimate load-carrying capacity considering residual stresses in the UHPC after cracking was provided. The results show that the transverse connection detail has good plastic deformation capacity and collaboratively supports both sides of the bridge deck. The error in predicting the ultimate load-carrying capacity of specimens under positive bending moments using the proposed theoretical calculation method is 3.9%, and for specimens under negative bending moments, the load-carrying capacity is controlled by local buckling of the steel, with a 3.1% diff erence between theoretical and measured values.
Chen Xu,Boyu Zhang,Siwei Liu,Qingtian Su 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.3
The steel-concrete double composite girder in the negative flexural region combines an additional concrete slab to the steel bottom flange to prevent the local steel buckling, however, the additional concrete slab may lower down the neutral axis of the composite section, which is a sensitive factor to the tensile stress restraint on the concrete deck. This is actually of great importance to the structural rationality and durability, but has not been investigated in detail yet. In this case, a series of 5.5 m-long composite girder specimens were tested by negative bending, among which the bottom slab configuration and the longitudinal reinforcement ratio in the concrete deck were the parameters. Furthermore, an analytical study concerning about the influence of bottom concrete slab thickness on the cracking and sectional bending-carrying capacity were carried out. The test results showed that the additional concrete at the bottom improved the composite sectional bending stiffness and bending-carrying capacity, whereas its effect on the concrete crack distribution was not obvious. According to the analytical study, the additional concrete slab at the bottom with an equivalent thickness to the concrete deck slab may provide the best contributions to the improvements of crack initiation bending moment and the sectional bending-carrying capacity. This can be applied for the design practice.
Dan Sun,Changyu Li,Hongyan Qin,Qingtian Zhang,Yiming Yang,Jun Ai 한국식물학회 2016 Journal of Plant Biology Vol.59 No.5
Resveratrol are the most important bioactive compounds found in Vitis amurensis. In this study, a somatic embryo induction system for V. amurensis was established in air-lift bioreactors for the production of biomass and resveratrol. The somatic embryos biomass growth was low on solid medium (69.60 g L−1) compared to in liquid medium in bioreactor (329.45 g L−1). Bioreactor cultures were found to be superior compared with solid medium culture not only in terms of biomass but also resveratrol productivity. Various culture parameters, including culture method, inoculum density, carbon source, and organic compounds were optimized. An inoculum density of 20 g L−1 embryogenic calli was found suitable for the accumulation of biomass and resveratrol production, whereas 10 g L−1 embryogenic calli increased the amount of resveratrol per fresh weight in somatic embryos. For bioreactor culturing, sucrose was an optimum carbon source and 500 mg L–1 casein hydrolysate acid was conducive to the biomass and resveratrol production. This result indicates that an efficient protocol for the large-scale production of resveratrol can be achieved by bioreactor culturing of V. amurensis somatic embryos and can be used as a source of medicinal raw materials.