The reuse of leather waste is a global challenge because of the increase of leather products. In this paper, collagen fiber (CF) was extracted from leather waste and polyvinyl alcohol (PVA) gel membranes containing CF with high mechanical property are fabricated by freeze–thaw method. Results shows that the composite gel membrane maintains the helical structure of CF. The tensile strength of the PVA/3CF‐FW increases to 58.5 MPa, while its elongation at break increases to 365%. The swelling ratio increases with the addition of CF, and the PVA/7CF composite gel membrane has the highest swelling ratio, which is 11.65. However, the crystallinity reduced with the addition of CF. Compared to the pure 24PVA gel membrane and the PVA/GA gel membrane, the PVA/CF composite gel membrane prepared by freeze–thaw method has a better mechanical property.Highlights
Taking leather waste as raw material to extract collagen fiber.
The gel membranes containing collagen fiber have hardly been reported.
The gel membranes show good swelling ratio and mechanical properties.
The SRC (steel-frame reinforced concrete) arch bridge is an important part of the development of arch bridges. Scholars worldwide have studied it from various aspects because of its stronger stiffness and stability than other types of bridges especially when crossing the canyon. The steel frame is a stress bracket during construction. Concrete becomes the main axial-pressure bearing structure when it fills the inner pipe and the encased frame. This article mainly focuses on the crack problems of SRC arch bridging during the postconstruction operation, local model of the midspan arch rib, and the equivalent relationship between the coefficient of expansion and the temperature of concrete. This study uses a cooling method to simulate the shrinkage process with detailed analysis of three properties including concrete shrinkage, temperature gradients, and concentrated hanger rod force. It is concluded that the SRC arch bridge will have large tensile stress on both inner and outer surfaces of slab and web when the temperature changes, and it is the main cause of cracks. The results agree well with measured data. At last, we come up with some reference suggestions in the design and construction of similar bridges in the future.
This paper presents a numerical study on the high-temperature mechanical properties of a long-span double-deck suspension bridge. The main focus of this paper is the behavior analysis of Wuhan Yangtze River Bridge. A three-dimensional thermal model of the bridge was established by the Fire Dynamics software (FDS) to obtain the 3D temperature field distribution, and the thermal analysis result was then applied to the three-dimensional finite element model of the suspension bridge. The shortest failure time of the main cable and sling was determined to obtain the rescue time of a bridge fire. According to the calculation results of the suspension bridge under a tanker fire initiated at the upper deck of the bridge, the middle lane in the upper deck of the suspension bridge was determined to be a safe lane. Thus, the tanker should be guided to go in this lane of the bridge. The numerical analysis of the experimental results shows that when the fuel tanker is located on the upper and lower floors of the bridge, the bridge structure is affected by the fire. When the oil tanker burns in the outermost lane of the upper bridge, it will have a great impact on the main cables and slings of the bridge. When the fuel tanker burns in the lower nonmotorized lane of the bridge, it will have a great impact on the upper stiffening beam steel plates and truss rods.
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