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The main bridge of Wanlong Bridge under construction is the first spatial self anchored suspension bridge with elliptical steel tower in the world. The saddle of this bridge adopts an self-adaptive space cable saddle combined with casting and welding, which has the following technical difficulties: the force of space cable saddle is complex. The longitudinal stiffness of the elliptical tower is large, and the slip resistance of the main cable saddle is prominent. The bottom of the saddle is a flexible support, the cable saddle and the main tower are co-deformed, and the tower-saddle connection structure is complicated in force transmission. In order to master the key technology of the main cable saddle and the tower-saddle connection structure of the self-anchored suspension bridge with elliptical tower and space cable, this paper carries out a systematic study by using numerical analysis method. The research conclusions are as follows: (1) When the bridge is subjected to (dead load+car+crowd+tap water+temperature+wind), the minimum friction coefficient µ that satisfies the requirements is 0.215, and the 12 mm vertical friction plates are required. (2) The maximum Von Mises stress and maximum vertical deformation of the main cable saddle under the condition of maximum cable force are 186.2 MPa and 1.572 mm, which meet the requirements of strength and stiffness. (3) In the structure connecting the main cable saddle and the steel tower, the force of the main cable saddle is transferred to the web of the steel tower in the form of vertical shear force through the supporting baffle. The shear force of the supporting baffle at the end is significantly greater than that of the middle baffle, and the non-uniformity coefficient of shear transfer is 1.29. (4) The support plate of the main cable saddle has a certain angle at the edge of the saddle area. The maximum longitudinal angle under the condition of empty cable is 0.366‰ rad, which should be taken into consideration in the saddle pushing construction. [ABSTRACT FROM AUTHOR]

Bone fractures are the most common form of musculoskeletal trauma worldwide. Numerous microRNAs (miRNAs) have been suggested to be participants in regulating bone‐related diseases. Recent studies revealed the regulatory role of miR‐22‐3p in osteogenic differentiation, but its role in fracture healing has not been investigated previously. Here, a rat femoral fracture model was established, Bone marrow mesenchymal stem cells (BMSCs) were isolated to detect the specific function and underlying mechanisms of miR‐22‐3p. MiR‐22‐3p and sclerostin domain‐containing 1 (SOSTDC1) expression was determined by RT‐qPCR and immunohistochemistry staining. The levels of proteins associated with osteogenic differentiation were assessed by western blotting. Flow cytometry was conducted to identify the isolated rat BMSCs. Alizarin red staining, alkaline phosphatase staining and Oil Red O staining were used to evaluate the osteogenic and adipogenic differentiation of rat BMSCs. The interaction between miR‐22‐3p and SOSTDC1 was verified using a luciferase reporter assay. Haematoxylin and Eosin (H&E) staining of the bone tissues was performed to analyse the effect of miR‐22‐3p on histopathological changes in vivo. MiR‐22‐3p was downregulated in the callus tissues of rat femoral fracture, while the expression of SOSTDC1 was upregulated. The isolated rat BMSCs had the capacity for both osteogenic and adipogenic differentiation. The differentiation capacity of BMSCs into osteoblasts was increased by miR‐22‐3p overexpression. MiR‐22‐3p activated the PI3K/AKT pathway by targeting SOSTDC1. SOSTDC1 overexpression and PI3K/AKT signalling inhibitor LY294002 abolished the enhancing effect of miR‐22‐3p overexpression on the osteogenesis of BMSCs. Thus MiR‐22‐3p facilitated the femoral fracture healing in rats. MiR‐22‐3p overexpression promoted fracture healing via the activation of PI3K/AKT pathway by targeting SOSTDC1. [ABSTRACT FROM AUTHOR]

The newly built Wujiang Super Major Bridge on Weng-an-Zunyi Railway leaps over a deep valley between two mountains. The topography at the bridge site is complex and the bridge design is difficult. This thesis describes the conceptual considerations and structural design of the main bridge first, and then carries out the static and dynamic simulation analysis of the bridge by using the space finite element software. Research conclusions: The stiff skeleton deck-arch bridge with a main span of 337 m has the advantages of large rigidity, small creep and less maintenance work. The main arch is designed with small rise-span ratio, taking into account safety, economy, environmental protection and aesthetics. The arch rib is composed of concrete-filled steel tubular skeletons and the encasing nonshrinage C55 concrete, and the internal forces in different components of the arch are improved by means of casing concretet in layers and segments. The composite girder is consisted of two I cross-section steels and concrete slabs, and the steel girder are connected by bombination of bolting and welding, which is convenient for manufacture, transport and construction. The arch abutment is an expanded foundation with ladder-shaped section, and permanent and temporary measures are used in foundation excavation to reduce construction risk. The numerical analysis shows that the rigidity, strength and stability of the bridge structure can meet the requirements of the code and the safety and riding comfort requirements of the mixed passenger-freight line. It can provide some references for other mountain railway bridge design. [ABSTRACT FROM AUTHOR]

The Mabian fault zone, distanced ∼200 km to the east of the Xianshuihe–Xiaojiang fault system, is located in the western vicinity of the relatively stable South China Block. Since 1917, about 54  M > 4.7 earthquakes, including the 1974 M s = 7.1 Mabian event have occurred around this fault zone, suggesting that significant strain is localized within the Mabian fault zone. Here, we built a 3-D finite element model to investigate the main parameters that possibly control strain localization around the Mabian fault zone averaged over the active deformation timescale. In the model, the Xianshuihe–Xiaojiang fault system is specified as a discontinuous contact interface for its motion governed by a Coulomb-friction law, and the crustal rheology is simplified as a frictional upper crust underlain by a viscoelastic lower crust. In addition, global positioning system (GPS) data are used to mimic the horizontal tectonic loading, and the model base is supported by a hydrostatic pressure. Numerical results show that with the weak fault strength and the low viscosity contrast between the Tibetan plateau and the South China Block, strain rates from motion of the southeastern Tibetan plateau could be propagated across the Xianshuihe–Xiaojiang fault system more widely within the Mabian fault zone. Constrained by the estimates on slip rates of the faults and on rheological structures of the crust, our optimal model predicts the effective friction coefficient of the Xianshuihe–Xiaojiang fault of 0.05–0.1. Under this condition, relative motion across the Xianshuihe–Xiaojiang fault system is largely partitioned by the geometric bend near the central portion of the fault system, resulting in a relatively high strain rate of 2.1–3×10–8 yr–1 accumulating around the Mabian fault zone. Keeping the weak strength of the fault, numerical results also show that if the central portion of the Xianshuihe–Xiaojiang fault system follows the Daliangshan fault, strain accumulation around the Mabian fault zone could be significantly reduced. It thus can be concluded that the strain partitioning from the weak strength and the special geometry of the Xianshuihe–Xiaojiang fault system must play a crucial role in active deformation around the Mabian area out of the Tibetan plateau deformation domain. This in turn means that in the Xianshuihe–Xiaojiang fault system, the Anninghe–Zemuhe fault is still the main boundary between the southeastern Tibetan plateau and the South China Block. [ABSTRACT FROM AUTHOR]