Concrete-filled Steel Tube Truss Research Articles

Performance of concrete-filled steel tube truss girders strength by adding reinforcement

Concrete filled steel tube (CFST) truss girder usually consists of CFST chords and hollow braces. The performance of steel tube truss girders filled with self-compacting concrete was investigated in this study. A total of eight CFST truss girders (Warren-vertical truss) specimens were tested. The main parameters were the concrete compressive strength and adding a reinforced bar in the concrete core of the bottom chord. Two of specimens without reinforcement were suggested as reference specimens. This study shows the load-deflection curves at the midspan, overall deflections, ultimate loads, flexural strength and failure modes of the tested specimens. The Proposed design equation found in the literature was used to predict the flexural strength of CFST trusses. The failure mode includes: weld fracture and shredding around joints and local buckling of the diagonal braces. Results show that the increase of concrete compressive strength caused a slight increase of the CFST truss strength by about (2.8%-10.34%), also the results showed that the best addition to the core concrete of the bottom chord was the circular steel tube compared with the addition of the steel bars.

Temperature action and effect of concrete-filled steel tubular bridges: A review

Abstract Concrete-filled steel tube (CFST) has been widely applied in bridges due to its excellent structural and constructional performance. In CFST bridges, temperature action is not only an important but also a special load that must be considered in bridge design, construction and structural evaluation. This paper presents an overview on current researches of the temperature action and effect of CFST bridges. The historical and spatial characteristics as well as corresponding influencing factors of temperature distributions are summarized, and classifications of temperature actions are also reviewed. Results show that in-depth investigations of the contributions of temperature influencing factors can help to effectively reduce the adverse temperature effects on CFST bridges in the design stage. Due to the lack of long-term measurements and insufficient use of historical meteorological data, research on the representative value along with correlation analysis of CFST temperature actions and meteorological parameters have to be further carried out. In the meanwhile, a decomposition method of temperature distribution is proposed based on structural effects of CFST bridges in this paper. The decomposed temperature actions can be used for more accurate effect calculation than traditional temperature action classification method, especially for CFST truss bridges. At last, specific temperature action patterns still need to be investigated in some of the special problems, such as longitudinal temperature differences along the CFST arch rib and thermal debonding in the CFST interface. Further investigations are required on the accurate simulation of temperature distribution of CFST bridges considering the shading effects of components and terrain.

Experimental Study of Self-Compacted Concrete-Filled Steel Tube (CFST) Truss Girders

Concrete filled steel tube one of the most important modern innovations in the world. This paper studies the performance of steel tube truss girders filled with self-compacting concrete. Four CFST truss girders specimens tested. The first novelty in this research was using square tubes to made truss girder; the main parameters were bottom chord concrete compressive grade and reinforce steel bar is embedded in the bottom chord (second novelty). One bar with a nominal diameter 16 mm was used to reinforce the concrete in the bottom chord while keeping the concrete in the top chord without reinforced. This paper shows the load-displacement curves at the mid-span, deflections along the span, peak loads, flexural strength, and failure modes of the tested specimens. The design equation was used to predict the flexural strength of CFST truss specimens. Results show that the flexural strength increased with increasing the concrete grade from 29.23MPa to 48.41MPa by about 4.5% and increased by about 10.27% when using reinforce steel bar embedded the concrete in the bottom chord.

Concrete-filled steel tube (CFT) truss girders: Experimental tests, analysis, and design

This paper investigates the behavior of Warren-vertical CFT truss girders by conducting both experimental tests and finite element analyses. Experimental tests on three CFT truss girders are first conducted. The test parameter is the compressive strength of the concrete infill. Finite element models, which were developed and benchmarked previously by the authors, are then used to further investigate the behavior of CFT truss girders and the influence of parameters such as the brace-to-chord strength ratio, shear span-to-depth ratio, and concrete compressive strength. Results from the parametric studies indicate that CFT truss girders are flexure dominated if (i) the brace-to-chord strength ratio ≥0.8 and (ii) the shear span-to-depth ratio ≥4.8. Both the experimental tests and FEM analyses indicate that the concrete compressive strength has negligible effects on the failure mode of CFT truss girders. Based on results from the experimental tests and FEM analyses, design equations are also proposed for estimating the flexural strength of Warren-vertical CFT truss girders.

Experimental behavior and analysis of prestressed concrete-filled steel tube (CFT) truss girders

Prestressed concrete-filled steel tube (CFT) truss girders usually consist of CFT chords, hollow steel tube braces, and high-strength prestressing strands. This paper investigates the behavior of prestressed CFT truss girders by conducting both experimental tests and finite element analyses. Experimental tests on five prestressed CFT truss girders are first conducted. The test parameters are the prestress level and shear span-to-depth ratio. Results from the experimental tests indicate that: (i) the initial flexural stiffness and flexural strength of prestressed CFT truss girders increase as the prestress level or shear-span-to-depth ratio increases, and (ii) the failure modes of prestressed CFT truss girders are influenced by the prestress level and shear span-to-depth ratio. Finite element models, which were developed previously by the authors for CFT truss girders, are then modified to predict the behavior of prestressed CFT truss girders. Comparisons with experimental load-deformation responses indicate that the developed finite element models can reasonably predict the behavior of prestressed CFT truss girders.

Study on Seismic Performance of CFST Frame and Truss

Concrete filled steel tube (CFST) got a good application in actual project. In order to further the seismic performance of the CFST, experiment was carried on two 1/5 scale models, which included one CFST frame, one CFST truss. Based on the experimental study, load-carrying capacity, stiffness, ductility, hysteretic property, energy dissipation and failure phenomena of each model were analyzed. The study shows that the seismic performance of CFST truss has high bearing capacity, stiffness, energy dissipation capacity and good ductility.

Behaviour of Composite Beam of CFST Truss with Diagonal Web Members

This paper presents the results of an experimental program for a novel composite beam of concrete-filled steel tube (CFST) truss with diagonal web members. This paper investigated the static performance and failure modes of the composite beam. Load-deformation relationships and deflection regulation of the test beam were obtained and its performance was evaluated in terms of its stiffness and bearing capacity. The strain distribution within critical components was also analyzed. The experimental results showed that the composite beam of CFST truss with diagonal web members has high strength and ductility performance. It markedly improves the stiffness and strength of the composite beam of CFST truss with straight web members

Behaviour of Composite Beam of CFST Truss with Diagonal Web Members

This paper presents the results of an experimental program for a novel composite beam of concrete-filled steel tube (CFST) truss with diagonal web members. This paper investigated the static performance and failure modes of the composite beam. Load-deformation relationships and deflection regulation of the test beam were obtained and its performance was evaluated in terms of its stiffness and bearing capacity. The strain distribution within critical components was also analyzed. The experimental results showed that the composite beam of CFST truss with diagonal web members has high strength and ductility performance. It markedly improves the stiffness and strength of the composite beam of CFST truss with straight web members

Finite Element Analysis on Static Performance on Combined Truss with Rectangular Steel Tube and Concrete-Filled Steel Tube

Finite element analysis on three trusses was carried out in order to study the performance of combined truss with steel tube and concrete filled steel tube. The first specimen was a RHS truss, the second one was a combined truss with steel tube and concrete filled steel tube, and the third one was a concrete-filled steel tube truss. The results show that the finite element model can reflect the static performance of combined truss and can carry out the affective parameters analysis, which can offer theory evidence for engineering application of combined truss. The damage of three trusses was all due to the joint failure and the failure mode was all punishing shearing failure, but the concrete filled changed by the failure place of joints. The bearing capacity of three trusses was controlled by the jionts and the strength and stiffness of jionts were increased by the concrete filled in the chord, therefore the bearing capacity of trusses was increased while the deformation of trusses was decreased. In combined truss with steel tube and concrete filled steel tube, the concrete-filled steel tube joints can improve the bearing capacity and the steel tube joint can satisfy the requirements of deformation, which have obvious advantages in the engineering application.