scholarly journals Research on the Reinforcement Mechanism and Safety Monitoring of Heavy-Duty Concrete-Encased CFST Columns

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Xiu-Hua Guo ◽  
Jin-Feng Jiao ◽  
Zhi-An Wu ◽  
Jian-Li Zhang
Keyword(s):  
Steel Tube ◽  
Steel Plates ◽  
Steel Pipe ◽  
Construction Simulation ◽  
Test Results ◽  
Heavy Duty ◽  
Whole Process ◽  
Axial Forces ◽  
Temporary Support ◽  
Cfst Columns

With the reinforcement project of a heavy-duty concrete-encased concrete-filled steel tube (CFST) column as the background, the mechanism of column reinforcement with supporting beams is proposed. The key mechanisms include the following: (1) designing the upper and lower corbel-shaped temporary support columns, (2) crack repairing the inner steel pipe using patch-shaped steel plates, and (3) replacing microwound concrete inside the steel pipe, which are all innovative and effective methods. Moreover, a system is developed for monitoring the safety during the reinforcement process and recovering the bearing capacity of the concrete-encased CFST column. The monitoring results indicate that the load conversion process of the temporary support columns lasts for 50 days, that the sum of the axial forces of the four supporting columns is 7,966.0 kN, accounting for 65% of the standard load, and that during the whole process, the structural components are safe and reliable. Finally, the construction simulation is in agreement with the field test results, which proves that the construction simulation developed based on the theory of slow time-dependent mechanics and the method of static nonlinear analysis is accurate.

scholarly journals Experimental and Numerical Analysis of Large-Scale Circular Concrete-Filled Steel Tubular Columns with Various Constructural Measures under High Axial Load Ratios

2018 ◽  
Vol 8 (10) ◽  
pp. 1894 ◽  
Author(s):  
Lidong Zhao ◽  
Wanlin Cao ◽  
Huazhen Guo ◽  
Yang Zhao ◽  
Yu Song ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Bearing Capacity ◽  
Axial Load ◽  
Large Scale ◽  
Steel Tube ◽  
Test Results ◽  
Welded Steel ◽  
Axial Forces ◽  
Circular Steel Tube ◽  
Cfst Columns

To investigate the effect of constructional measures (including horizontal and vertical stiffeners, rebar cages, embedded steel tubes, and cavity welded steel plates) under high axial load ratios on the seismic performance of concrete-filled steel tubular (CFST) columns, quasi-static tests for six large-scale CFST columns with various constructional measures are performed. All specimens are subjected to identical axial forces. The failure mode, hysteresis characteristics, bearing capacity, stiffness degradation, ductility, and energy dissipation of specimens are analyzed. The study shows that the horizontal stiffener delays the occurrence and severity of column base buckling, the vertical stiffener improves the bending resistance capacity and initial stiffness of the member, the rebar cage improves the ductility, and the embedded circular steel tube significantly improves the member’s bearing capacity, ductility, and energy dissipation. When an internal circular steel tube and cavity welded steel plate are applied in tandem, the section steel ratio increases by 4.42% and the bearing capacity improves by 42.72%. A finite element model is created to verify test results, and simulation results match the test results well.

Experimental Research and Finite Element Analysis of Concrete-Filled Steel Box Columns with Longitudinal Stiffeners

2011 ◽  
Vol 287-290 ◽  
pp. 1037-1042 ◽  
Author(s):  
Jun Guang Zhang ◽  
Yong Jian Liu ◽  
Jian Yang ◽  
Kai Lei Xu
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Local Buckling ◽  
Steel Tube ◽  
Steel Plates ◽  
Thin Wall ◽  
Test Results ◽  
Element Analysis ◽  
Longitudinal Stiffeners ◽  
Box Columns

For further study of mechanical properties of concrete-filled steel box columns (CFSBCs) with longitudinal stiffeners, axially loading tests of CFSBCs with longitudinal stiffeners was conducted to obtain their ultimate bearing capacity and failure modes. The test results were compared with those of hollow steel box columns with longitudinal stiffeners. Cross section of the test specimen was scaled from a chord member of Dongjiang Bridge. The experimental results show that failure mode of CFSBCs with longitudinal stiffeners is local buckling of steel plates, which is different from that of concrete-filled thin wall steel tube columns with longitudinal stiffeners. Although longitudinal stiffeners can prevent global buckling of steel plates, the effect is less obvious than that of concrete-filled thin wall steel tube columns. Meanwhile, three-dimensional finite element models (FEM) of the specimens were modeled using computer program ANSYS to obtain bearing capacities and load-strain curves. The FEM results coincide quite well with the test results. Further, influence of width to thickness ratio on mechanical behavior of CFSBCs was analyzed using FEM.

scholarly journals Derivation of the unified equation of axial compression of CFST columns

2020 ◽  
Vol 143 ◽  
pp. 01004
Author(s):  
Ruoyang Zhou ◽  
Xiaoxiong Zha
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Limit Equilibrium ◽  
Concrete Columns ◽  
Steel Tube ◽  
Steel Reinforcement ◽  
Steel Plates ◽  
Steel Tubes ◽  
High Rise ◽  
Cfst Columns

The steel tube concrete columns with steel reinforcement cages, steel plates and steel tubes has been used in super high-rise buildings, which are called concrete-filled steel tubular (CFST) columns with internal stiffeners. Based on the theory of limit equilibrium, the unified equation for the axial bearing capacity of the CFST columns with internal stiffeners is obtained. The derived equation in this study can provide reference for the future engineering applications.

scholarly journals Diaphragm axial capacity for external diaphragm connections (EDCs) in square CFST column structures

2019 ◽  
Vol 52 (3) ◽  
pp. 134-140
Author(s):  
Helmy Tjahjanto ◽  
Gregory MacRae ◽  
Anthony Abu ◽  
Charles Clifton ◽  
Tessa Beetham ◽  
...  
Keyword(s):  
Finite Element ◽  
Steel Tube ◽  
Frame Structures ◽  
Finite Element Analyses ◽  
Moment Frame ◽  
Axial Capacity ◽  
Axial Forces ◽  
Beam Method ◽  
Cfst Columns ◽  
Lower Bound Estimate

This paper evaluates external diaphragm axial capacity in moment frame structures with square concrete-filled steel tubular (CFST) columns considering bidirectional loading. Three design methods were considered: (1) the CIDECT method; (2) the equivalent beam method; and (3) the tie method. Finite element analyses were conducted to investigate the behaviour of an external diaphragm plate connected to a square CFST column under varied bidirectional diaphragm axial forces. It is shown that the perpendicular diaphragm axial forces did not reduce the diaphragm axial capacity significantly, which is consistent with the assumptions made by the CIDECT method and the tie method. The CIDECT method, in some cases, was not conservative. Among the considered methods, the tie method was the most justifiable method, although in some cases the capacity predictions were too conservative. The tie method was later modified by considering the contribution of the steel tube in addition to the diaphragm plate in calculating the diaphragm axial capacity. The modified tie method was shown to accurately predict a lower bound estimate of the capacity of an external diaphragm connection.

INFLUENCE OF BOND AND FRICTION ON TENSILE STRENGTH OF PERFORATED STEEL PLATE CONNECTOR UNDER CONFINEMENT

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yuka Nagaoka ◽  
Takashi Fujinaga ◽  
Teruhisa Tanaka
Keyword(s):  
Steel Plate ◽  
Steel Tube ◽  
Steel Plates ◽  
Controlled Environment ◽  
Building Performance ◽  
Pull Out ◽  
Experimental Parameters ◽  
Cfst Columns ◽  
And Behavior ◽  
Pull Out Strength

Concrete-filled steel tube (CFST) columns are commonly used in Japan, which utilize onsite full-strength welded splices between columns. However, onsite welding requires high technical skill and a controlled environment. Further, this type of splice is expensive and, in most cases, is not necessary for dependable building performance under severe earthquake loading conditions. Recently, new types of CFST column splices have been developed that enhance constructability and avoid the need for onsite welding. In the proposed column splice method, perforated steel plates are placed on each column half and are welded into place. To evaluate the performance of this splice, it is important to determine the pull-out strength and behavior modes of the perforated steel plates embedded into the CFSTs. In this paper, a pull-out experiment with perforated steel plates embedded into a square CFST stub is conducted. The experimental parameters are the bond between the steel plate and the concrete, the embedded length of the perforation, and the extra length of the steel plate. The effect of the bond and friction strength between the steel and concrete are discussed, and a design formula for the pull-out strength of the perforated steel plate is examined.

scholarly journals Effect of Concrete Age and Creep on the Behavior of Concrete-Filled Steel Tube Columns

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
HaiYang Wang ◽  
XiaoXiong Zha ◽  
Wei Feng
Keyword(s):  
Numerical Models ◽  
Axial Loading ◽  
Steel Tube ◽  
Test Results ◽  
Empirical Formulas ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Concrete Filled Steel Tube ◽  
Practical Design ◽  
Cfst Columns

The influence of concrete age and creep on the ultimate axial loading capacity of concrete-filled steel tube (CFST) columns is experimentally and numerically investigated. After validation of numerical models, a parametric study is conducted and the results are used to formulate empirical formulas for predicting the ultimate axial load-bearing capacity of the columns. Formulas are also proposed for predicting both the composite creep and aging coefficients of the CFST columns, which consider the confinement action of steel tubes on concrete. Then, the proposed formulas are validated independently by comparing their predictions with existing test results performed by other researchers. The comparisons show that the empirical formulas have the potential to be used in the practical design of CFST columns.

Study on shear performance of the connection with external stiffening ring between square steel tubular column and unequal-depth steel beams

2020 ◽  
pp. 136943322098166
Author(s):  
Shuhao Yin ◽  
Bin Rong ◽  
Lei Wang ◽  
Yiliang Sun ◽  
Wuchen Zhang ◽  
...  
Keyword(s):  
Failure Modes ◽  
Plastic Hinge ◽  
Steel Tube ◽  
Nonlinear Finite Element ◽  
Steel Beams ◽  
Finite Element Models ◽  
Test Results ◽  
Panel Zone ◽  
Load Paths ◽  
Shear Performance

This paper studies the shear performance of the connection with the external stiffening ring between the square steel tubular column and unequal-depth steel beams. Two specimens of interior column connections were tested under low cyclic loading. The deformation characteristics and failure modes exhibited by the test phenomena can be summarized as: (1) two specimens all exhibited shear deformation in steel tube web of the panel zone and (2) weld fracture in the panel zone and plastic hinge failure at beam end were observed. Besides, load-displacement behaviors and strain distributions have been also discussed. The nonlinear finite element models were developed to verify the test results. Comparative analyses of the bearing capacity, failure mode, and load-paths between the equal-depth and unequal-depth beam models have been carried out.

Design of Static Test Model for Three-Tower Cable-Stayed Self-Anchored Suspension Composed Bridge

2011 ◽  
Vol 243-249 ◽  
pp. 1528-1535
Author(s):  
Yu Zhao ◽  
Yong Jun Zhou ◽  
Jing Sun ◽  
Jin Tao Tang ◽  
Xu Li
Keyword(s):  
Complex System ◽  
Finite Element ◽  
Element Model ◽  
Test Model ◽  
Test Results ◽  
Static Test ◽  
Whole Process ◽  
Aesthetic Appearance ◽  
Load Carrying ◽  
Novel Structures

Cable-stayed self-anchored suspension composed bridges have novel structures and aesthetic appearance with complex system and difficulty for design and construction. In order to acquire a better knowledge of the load-carrying capability of this type of bridges, based on a real bridge and the theory of abnormal similarity, a full-bridge scaled down(1:20) test model was built to simulate the whole process of construction. The test results were preferably fit the theoretical calculation value. It can be seen that the design of the bridge was reasonable, and the accuracy of the calculation of finite element model was verified at the same time. The test and the related results can be used as the reference for the test and design of the similar bridges.

Cutting of a Longitudinally Stiffened Plate by a Wedge

1994 ◽  
Vol 38 (04) ◽  
pp. 340-348 ◽  
Author(s):  
Jeom Kee Paik
Keyword(s):  
Plate Thickness ◽  
Wedge Angle ◽  
Steel Plates ◽  
Test Results ◽  
Stiffened Plate ◽  
Absorbed Energy ◽  
Dimensionless Analysis ◽  
Cutting Length ◽  
Plate Aspect Ratio ◽  
Stiffened Steel

The aim of this study is to obtain test data for longitudinally stiffened steel plates which are quasistatically cut by a rigid wedge, idealizing the deck or bottom platings in ship collision or grounding, and also to derive an empirical formula relating the absorbed energy and cutting length. A series of tests for longitudinally stiffened high-tensile steel plates is conducted, varying several factors, namely plate thickness, plate aspect ratio, angle/shape of wedge tip and property of stiffeners. A total of 50 specimens with thicknesses in the range of 3.4 to 7.8 mm and wedge angles of 15, 30, 45, and 60 deg, including one unstiffened and two horizontally stiffened plate specimens, were tested. The importance of each parameter and its effect on the cutting response are investigated. By dimensionless analysis of the test results obtained here, the energy absorbed while a longitudinally stiffened plate is cut by a wedge is expressed as a function of cutting length, yield stress, equivalent plate thickness, and wedge angle. Incorporation of dynamic effects into the static formula is suggested. A comparison of the proposed solutions with the previous formulas or drop-hammer test results is made.

scholarly journals Axial Behaviour of Slender RC Circular Columns Strengthened with Circular CFST Jackets

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yiyan Lu ◽  
Tao Zhu ◽  
Shan Li ◽  
Weijie Li ◽  
Na Li
Keyword(s):  
Bearing Capacity ◽  
Ductile Failure ◽  
Steel Tube ◽  
Experimental Results ◽  
Strengthening Effect ◽  
Load Bearing Capacity ◽  
Rc Columns ◽  
Load Bearing ◽  
Cfst Columns ◽  
Material Utilization

This paper investigates the axial behavior of slender reinforced concrete (RC) columns strengthened with concrete filled steel tube (CFST) jacketing technique. It is realized by pouring self-compacting concrete (SCC) into the gap between inner original slender RC columns and outer steel tubes. Nine specimens were prepared and tested to failure under axial compression: a control specimen without strengthening and eight specimens with heights ranging between 1240 and 2140 mm strengthened with CFST jacketing. Experimental variables included four different length-to-diameter (L/D) ratios, three different diameter-to-thickness (D/t) ratios, and three different SCC strengths. The experimental results showed that the outer steel tube provided confinement to the SCC and original slender RC columns and thus effectively improved the behavior of slender RC columns. The failure mode of slender RC columns was changed from brittle failure (concrete peel-off) into ductile failure (global bending) after strengthening. And, the load-bearing capacity, material utilization, and ductility of slender RC columns were significantly enhanced. The strengthening effect of CFST jacketing decreased with the increase of L/D ratio and D/t ratio but showed little variation with higher SCC strength. An existing expression of load-bearing capacity for traditional CFST columns was extended to propose a formula for the load-bearing capacity of CFST jacketed columns, and the predictions showed good agreement with the experimental results.

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