Mechanical properties of curved composite box girders with corrugated steel webs

Sumei Liu,Wouter De Corte,Hanshan Ding,Luc Taerwe 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

Several methods derived for use on traditional concrete curved box girders (CBGs) are used in design practice. However, these typically consider only one elastic modulus and one shear modulus, and consequently cannot be applied directly to CBGs with corrugated steel webs (CSWs) due to the large shear deformations and small longitudinal stiffness of CSWs, while these shear deformations are small and usually ignored for common concrete webs. In this paper, firstly, the flexure-torsion governing differential equations considering the shear deformations and the accordion effect of CSWs, and the distortion governing differential equation considering the accordion effect of CSWs are derived for CBGs with CSWs. A practical method which can solve the deflections, torsional angles, distortional angles, stresses and internal forces of simple and continuous CBGs with intermediate diaphragms is proposed. Secondly, the results of a series of tests performed on three CBGs with CSWs, published test results, as well as finite element analysis results and theoretical results of straight box girders (SBGs) with CSWs are used to verify the correctness of the analytical method. The agreement between analytical, experimental and numerical results is good. Finally, a parametric analysis is conducted and the results show that: (a) the influence of shear deformations of CSWs on the deflections of CBGs with CSWs increases with increasing curvature radius R. For SBGs with CSWs, the deflections may increase by 30% when considering shear deformations. For CBGs with CSWs, the deflection increase ranges between 8% and 30% for concentrated loads depending on the curvature radius. (b) the distortional shear stress, which is small and typically neglected for CBGs with concrete webs, may be as big as, or larger than the flexural shear stress, and must be considered. The restrained torsional shear stress, which is also small and typically neglected for CBGs with concrete webs, can reach 9% of the flexural shear stress, and also must be considered.

In-Plane Stability of Concrete-Filled Steel Tubular Parabolic Truss Arches

Changyong Liu,Qing Hu,Yuyin Wang,Sumei Zhang 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.4

For determining the in-plane buckling resistance of a concrete-fi lled steel tubular (CFST) arch, the current technical code GB50923-2013 specifi es the use of an equivalent beam-column method which ignores the eff ect of rise-to-span ratio. This may induce a gap between the calculated result and actual stability capacity. In this study, a FE model is used to predict the buckling behavior of CFST truss arches subjected to uniformly distributed loads. The infl uence of rise-to-span ratio on the capacity of truss arches is investigated, and it is found that the stability capacity reduces as rise-to-span ratio declines. Besides, the calculations of equivalent slenderness ratio for diff erent truss sections are made to consider the eff ect of shear deformation. Moreover, based on FE results, a new design equation is proposed to predict the in-plane strength of CFST parabolic truss arches under uniformly distributed loads.

Experimental Investigation into In-plane Stability of Concrete-Filled Steel Tubular Parabolic Arches Under Five-Point Concentrated Loads

Qing Hu,Changyong Liu,Changchun Yuan,Yuyin Wang,Sumei Zhang 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.6

This paper deals with experimental investigations into in-plane stability of fi xed concrete-fi lled steel tubular (CFST) parabolic arches. Three CFST arches with the same span but diff erent rise-to-span ratios were tested under fi ve-point symmetrical concentrated loads over the full span. All applied loads were controlled in synchronization. The test results show that the test arches buckled in an antisymmetric failure mode and the section positions with the maximum deformation were slightly diff erent for three test arches. It is found that the bearing capacity of CFST arches decreased signifi cantly with the decline of rise-to-span ratios, and the outer steel tube provided signifi cant confi nement eff ects on the core concrete after the load reaches 80% of the load-carrying capacity. Moreover, comparisons between the test and fi nite element results indicate that the existing beam-element modeling method can predict the in-plane stability performance of CFST arches very well.

Effects of LED Light Quality Combinations on Growth and Leaf Colour of Tissue Culture-Generated Plantlets in Sedum rubrotinctum

Si Chuncan,Lin Ying,Luo Sumei,Yu Yanhua,Liu Ruiqing,Naz Misbah,Dai Zhicong 한국원예학회 2024 원예과학기술지 Vol.42 No.1

Different plants have different requirements with regard to light quality, including combinations of R/B LED light on tissue-culture-generated plants. However, the effects of R/B LED light combinations on the growth and colour changes of leaves in succulent plants remains unknown. In this study, to identify the most beneficial light quality and R/B light ratios for the growth of the succulent plant species Sedum rubrotinctum and its production of attractive colours, the growth parameters, pigment levels and leaf colour phenotypes of tissue-culture-generated S. rubrotinctum plantlets were evaluated when the plantlets were exposed to R, 4R1B, 3R1B, 2R4B, B and W treatments for 90 days. The results showed that light quality obviously influenced the growth and leaf colour of tissue-culture-generated S. rubrotinctum plantlets. R light hastened the elongation of stems, and B light was more beneficial for biomass accumulation and leaf and root growth. However, compared with B light, R light, and W light, the R/B combination resulted in a greater amount of fresh biomass and higher values for the shoot/root FW, stem diameter, crown width, total root length, root surface area, and root volume. The R/B combination also markedly increased the contents of anthocyanins and the R/green chromaticity of the leaves. In addition, a principal component analysis (PCA) revealed the following comprehensive ranking: 4R1B > 2R4B > 3R1B > W > B > R. Therefore, the 4R1B combination is suggested as the best treatment for promoting the growth of tissue-culture-generated S. rubrotinctum plantlets and their production of attractive colours. This study provides a practically significant and optimal solution for growth regulation via light quality for the production of S. rubrotinctum as well as important implications for other succulent plant species in the Crassulaceae family.

Treatment of Syringomyelia Characterized by Focal Dilatation of the Central Canal Using Mesenchymal Stem Cells and Neural Stem Cells

Mo Li,Wang Xinyu,Qi Boling,Cui Shengyu,Zheng Tianqi,Guan Yunqian,Ma Longbing,Liu Sumei,Li Qian,Chen Zhiguo,Jian Fengzeng 한국조직공학과 재생의학회 2024 조직공학과 재생의학 Vol.21 No.4

BACKGROUND: Syringomyelia is a progressive chronic disease that leads to nerve pain, sensory dissociation, and dyskinesia. Symptoms often do not improve after surgery. Stem cells have been widely explored for the treatment of nervous system diseases due to their immunoregulatory and neural replacement abilities. METHODS: In this study, we used a rat model of syringomyelia characterized by focal dilatation of the central canal to explore an effective transplantation scheme and evaluate the effect of mesenchymal stem cells and induced neural stem cells for the treatment of syringomyelia. RESULTS: The results showed that cell transplantation could not only promote syrinx shrinkage but also stimulate the proliferation of ependymal cells, and the effect of this result was related to the transplantation location. These reactions appeared only when the cells were transplanted into the cavity. Additionally, we discovered that cell transplantation transformed activated microglia into the M2 phenotype. IGF1-expressing M2 microglia may play a significant role in the repair of nerve pain. CONCLUSION: Cell transplantation can promote cavity shrinkage and regulate the local inflammatory environment. Moreover, the proliferation of ependymal cells may indicate the activation of endogenous stem cells, which is important for the regeneration and repair of spinal cord injury. BACKGROUND: Syringomyelia is a progressive chronic disease that leads to nerve pain, sensory dissociation, and dyskinesia. Symptoms often do not improve after surgery. Stem cells have been widely explored for the treatment of nervous system diseases due to their immunoregulatory and neural replacement abilities. METHODS: In this study, we used a rat model of syringomyelia characterized by focal dilatation of the central canal to explore an effective transplantation scheme and evaluate the effect of mesenchymal stem cells and induced neural stem cells for the treatment of syringomyelia. RESULTS: The results showed that cell transplantation could not only promote syrinx shrinkage but also stimulate the proliferation of ependymal cells, and the effect of this result was related to the transplantation location. These reactions appeared only when the cells were transplanted into the cavity. Additionally, we discovered that cell transplantation transformed activated microglia into the M2 phenotype. IGF1-expressing M2 microglia may play a significant role in the repair of nerve pain. CONCLUSION: Cell transplantation can promote cavity shrinkage and regulate the local inflammatory environment. Moreover, the proliferation of ependymal cells may indicate the activation of endogenous stem cells, which is important for the regeneration and repair of spinal cord injury.