Papers by Keyword: CFST

Abstract: The demolished concrete lumps (DCLs) have been demonstrated to replacement partial coarse aggregates when casting concrete. However, few studies had focused on the sensitivity of factors affecting mechanical behavior of slender square steel slender columns filled with DCLs and fresh concrete (FC) under axial compression. This research was carried out on the basis of Bo Wu's study. The Orthogonal design method was adopted in this experiment. The experimental studied involved 12 Concrete-Filled Steel Tube (CFST) columns. Each columns diameter was 159mm, the length of specimens was 2000, 2200 and 2400 mm. The Diameter-to-thickness (D/t) ratio was 79, 53 and 40. The replacement ratio of FC by DCLs was 0, 20, 40 and 60%. Test results indicated that the slenderness ratio was the most sensitive factor on the bearing capacity of slender columns under axial compression, followed by D/t ratio, and the DCLs replacement ratio was smallest factor. The ultimate bearing capacity decreased slightly with increasing DCL replacement ratio. The DCLs had slightly affect on the mechanical performances of slender CFST columns. the code CECS 28:2012 was used to calculate the bearing capacity of slender CFST columns filled with DCLs under axial compression.

Abstract: With the span of CFST (Concrete Filled Steel Tube) arch bridges getting much longer, the dynamic performance of them is becoming more and more advanced. In order to evaluate the structure of CFST arch bridges in a comprehensive way, it is necessary to take the dynamic performance of this kind of bridges into consideration. Methods of doing the dynamic analysis can be divided into two kinds: one is traditional theoretical analytical method, which is only suitable for simple arch bridge models; the other is FEM (Finite Element Methods), which is able to simulate the real structure and lead to more precise results. This paper attempts to study the calculation theory of free vibration characteristic of arch bridges through theoretical analytical method, and then it will do an empirical study on the dynamic performance of a CFST arch bridge by FEM to test the conclusion of theoretical study.

Abstract: In order to provide a basis for designing outer annular-stiffener type steel castellated beam (OATSCB) - concrete filled steel tube (CFST) joint, the factors that influence the load-displacement skeleton curve of this kind of joint is analyzed. OATSCB - CFST joint with different influencing factors are designed, and their loading process is simulated by using finite element software ABAQUS. Before simulating, the simulating method is verified by previous test result. The corresponding load-displacement skeleton curves of those joints are also extracted. By comparing these curves in diagram, the following conclusions can be gotten: OATSCB - CFST joint has good seismic performance; steel yield strength, steel ratio and beam to column linear stiffness ratio are the important factors that influences the skeleton curve of this type of joint; opening rate is an important factor for this type of joint to form "strong column weak beam" yield mechanism.

Abstract: Through the experiment of the six node models, this article obtained the axial force-deformation curves of the web members, the equivalent stress distribution curves under different loads of the tower within the scope of the node plate length. The result shows that: the stress level in the node area increases with the growth of the radius-thickness ratio; the node without stiffening ribs prone to appear node plate out-of-plane buckling with a lower carrying capacity, and the pillar got a higher stress concentration at the front end of the node plate; while the exists of the stiffening rib can not only improve the bearing capacity of the tube plate nodes, but also avoid the early out-of-plane buckling of the node plate, the failure mode of these node is compression web member buckling failure, meanwhile, the distribution of the tower equivalent stress at the node area gets much more uniform. It follows that, the bearing capacity of the node is not only associating with the thickness of the node plate and the radius-thickness ratio, but also suffering the important influence of stiffening rib.

Abstract: The mechanical behavior of joints on lattice wind turbine tower of concrete-filled steel tubular(CFST) is very complex, the safety and reliability of joints is very important for the whole structure. To better understand the mechanical properties of the joints, we design a static loading test of 3 KT-type CFST joints. According to the test, we make analysis about the failure progress, equivalent stress of joint intersection and the relation of load-defomation. The results showed that due to the presence of concrete, the failure mode of CFST joints is web members failed. The failure characteristic of overlap joints is the instability of compression web member while the gap joints are the weld tear of tensile web member. With the increase of the overlap ratio, the distribution of the equivalent stress is more uniform. The high stress area is in the gap and the tower wall which between the crown point and saddle point in tensile side.

Abstract: The impact of blast load is always taken into consideration in significant pillar bearing component and protective construction. The LS-DYNA software was employed to simulate three typical concrete filled steel tubular (CFST) columns under blast load. The JHC model was used for concrete material and the MAT_PLASTIC_KINEMATIC model which accounted for the strain rate used for steel. Three section concrete-filled steel tube columns are analyzed in different proportion of distance and get the damage form of pillars and displacement of key points. The results show: In proportion to the same distance, the antiknock ability of circular cross section is better than the other two sections. Although in filled concrete damage is serious, but the steel tube columns improve the ductility of the columns. With the increase of proportion of distance, pillar deformation gradually decrease.