Papers by Keyword: Concrete-Filled Steel Tube (CFST)

Abstract: In many developed countries, concrete filled steel tubular arch bridges are being constructed for roads and railway lines. The CFST arch bridges use steel tubular arches with self consolidating concrete pumped inside and the steel tube provides confinement to the concrete infill. Also, these concrete filled steel tubes have enhanced ductility, better seismic performance, aesthetic quality, lesser consumption of materials and self weight, speedy construction and small vibrations according to studies conducted earlier. Due to the presence of steel tube, local buckling of arch is delayed and reduces the ingress of moisture when exposed to harsh environmental conditions. This paper aims to find the seismic performance of CFST arch bridges in terms of seismic output and deformation when compared to conventional bridges being currently constructed.

Abstract: Diagrid structures are exterior structures, consisting of diagonal struts and ties in the periphery and an interior core. These diagonal members carry gravity load and lateral load by the axial action of the member. Due to the structural efficiency of diagrids, interior and corner columns can be avoided thereby providing flexibility in the floor plan. The diagrid structures are emerging as popular structural system in many developed countries of the world, but in India it is yet to gain importance. This paper presents a review on the literature of diagrid structures. Studies conducted on diagrid structures to determine the diagrid angle for the efficient design is presented. The stiffness-based methodology adopted for determining preliminary member sizes of steel diagrid structures and the effect of shear lag on high rise buildings with diagrid and its comparison with framed tube structures are discussed. The distribution of the load resisted by interior frame and diagrids is outlined. The parameters used in the comparison of analysis are time period, top storey displacement, inter-storey drift and storey shear. This paper also reviews the studies on the comparison of diagrids with regular configuration and diagrids with varying angles. The analysis and comparison of diagrid and conventional structural system on the basis of consumption of steel, structural weight and displacement are also highlighted. This review covers diagrids with all the materials in practice namely concrete, steel and concrete-filled steel tube(CFST).

Abstract: Every year our country will produce large amounts of waste concrete, bring negative effect to the ecological environment. How to realize the recycling of waste concrete utilization has great significance for the sustainable development of ecology, environmental protection and social. This paper introduces the characteristics of recycled concrete and domestic experts and scholars research on it, and put forward prospect of the future of recycled concrete.

Abstract: The finite element analysis method of variable cross-sectional Concrete-Filled Steel Tubular (CFST) laced columns is put forward. The influence of longitudinal elements slope and slenderness ratio on stability factor are analyzed, and the computational formula of slenderness ratio of variable cross-sectional CFST laced columns is presented. On the basis of the analytical results, a rational methodology for calculating the stability factor of four-element variable cross-sectional CFST laced columns is proposed.

Abstract: Utilization of waste concrete has a great significance for environmental protection; concrete filled steel tube is a way of utilization of waste concrete. At the same time, the recycled concrete on the center tube has a "hoop" function, can compensate for the deviation of mechanical properties of recycled aggregate concrete. This paper introduces the characteristics of steel recycled concrete, and introduces the research status of domestic experts and scholars on it, based on the above; the future application of the recycled concrete in steel pipe is presented.

Abstract: Nonlinear finite element parameters analysis on the lattice type steel pipe concrete wind turbine tower, it shows the entire process of load bearing, failure mode and ultimate bearing capacity, researches on the influence law of aspect ratio, form of tower webs, tower diameter to thickness ratio and web member stiffness to tower column stiffness ratio on the ultimate bearing capacity and tower failure mode. The finite element analysis results shows that the tower aspect ratio λ, the diameter-thickness ratio γ of tower columns and the increase of stiffness ratio β between web members and tower columns has great influence on ultimate bearing capacity and failure mode, while the form of webs has small influence on that. with the increase of tower aspect ratio λ, the decrease of diameter-thickness ratio γ of tower columns and the increase of stiffness ratio β between web members and tower columns, the ultimate bearing capacity of this kind of latticed towers increase, the failure mode changed from Web local buckling to The combined damage of Web local buckling and the tension tower yield. This paper suggests that in the design of wind turbulent generator tower, the tower aspect ratio λ should be best controlled at 1/9, the bottom layers of this kind of tower should best use the re-divided web members, and other web member forms used on above layers, the diameter-thickness ratio γ of tower column should be taken less than 30, and the stiffness ratio β between webs and columns should be controlled less than 0.05 in order to avoid damage occurring on the tower columns earlier than the webs. The results can provide evidence for the engineering design.

Abstract: The concrete filled steel tubular (CFST) structure takes full advantages of the interaction of two materials in the process of loading, while the thermal performance parameters between steel tube and concrete are different, and the outside temperature changes makes the structural section produce a greater temperature gradient, which leads to the uncoordinated deformation between them. In this paper, the thermal conductivity of experimental system is carried on the theoretical analysis, then the distribution regularities of sectional temperature are obtained through the testing its of CFST under variable temperature effect, and the larger temperature difference will produce the temperature stress, which affects the bonding performance of structural interface. So in order to better analyze the influence which is impacted on the mechanical performances of structure by the combination effect of multiple factors such as temperature and load, such paper can provide the theoretical and experimental foundation.

Abstract: The focus of this research program is T-shaped CFT central column to steel frame beam connection. 3 joints with strong columns-weak beams and 1 joint with strong beams-weak columns 1:2 scale specimens were tested under constant axial loads and cyclic horizontal loads. Overall impact of axial force ratio and beam to column linear stiffness ratio on joint failure mechanism, hysteretic behavior, deformation ductility, and energy dissipation capability was investigated. Results showed that the failure mechanism for specimens with strong columns-weak beams was local buckling of the steel beam flanges and formation of the plastic hinges. There was minimum damage on the concrete column and joint panel zone. For a specimen with strong beams-weak columns, there was local buckling fracture on steel tube above and below the joint panel zone. Crushing of the core concrete was also observed with formation of the column hinges. It was found that both axial forces and beam to column linear stiffness ratio had impacts on joint capacity and ductility behavior of the specimens. Experiment results showed that the joint models had deformation ductility factor between 3.39 and 3.91 and viscous damping ratio between 0.46 and 0.51.

Abstract: Concrete filled double skin steel tubes which is developed on the basis of concrete filled steel tube, it is a new member. Combination of Chinese and foreign literature, this paper comprehensively discusses the research results about concrete filled double skin steel tubes member, then put forward the further research work, for concrete filled double skin steel tubes structure in deeply study to play a guiding role.

Abstract: The measurement accuracy of the cable tensions in the hanger rods of concrete filled steel tube arch bridges is important for the correct evaluation of bridges condition. Based on Jinpan Bridge-a half through concrete filled steel tube arch bridge with 80 m span in Tiantai, it was put forward the vibration frequency method for testing and evaluate suspender tensions with the help of analysis vibration characters of the suspender. The precision of cable force calculation formula was verified after comparing the practical tension with the designed tension obtained from tension jack method. Then, according to the test results and values predicted by the presented cable force calculation formula, the cable tensions were adjusted. Cable tension test results in the finished bridge show that this method is feasible.