Abstract:The axial compressive performance of novel L-shaped and T-shaped concrete-filled square steel tube (L/T-CFSST) column was assessed in this study. Ten L/T-CFSST columns were tested to failure under axial load. The experimental data were used to determine various failure modes, bearing capacities, and load-displacement curves. The test parameters included the section form, steel tube thickness, steel yield strength, and slenderness ratio. The axial compressive performance of the L/T-CFSST column proved favorable… Show more
“…On the other hand, the hoop coefficient, ξ, of the specimen decreases with the increase of the strength of concrete, which leads to the decrease of the restraint effect of multi-cavity steel tube on concrete. This further accelerates the decline rate of bearing capacity and reduces the ductility of the specimen (Wang, Zhou, et al, 2020).…”
Multi-cavity concrete-filled steel tube special shaped column (CFSTSSC) combines the excellent characteristics of multicavity steel tube and core concrete. CFSTSSC has the advantages of high bearing capacity, good ductility, and strong energy dissipation capacity. At present, accurate calculation methods for these kinds of structures are limited and research into crossshaped and L-shaped multi-cavity CFSTSSCs is not available. Therefore, the axial compression behavior of cross-shaped and L-shaped multi-cavity CFSTSSCs has been investigated, though experimental research and numerical simulation, in this study. First, axial compression tests were carried out on three cross-shaped and three L-shaped multi-cavity CFSTSSCs to analyze their failure modes, axial load-strain curve, ductility index, and ultimate bearing capacity. Then, finite element (FE) calculation models of cross-shaped and L-shaped multi-cavity CFSTSSCs were established. The FE models are in good agreement with the experimental results, which provides a foundation for further parameter analysis and failure mechanism study of special shaped columns. Finally, combining parameter analysis and limit equilibrium theory, equations for calculating the ultimate bearing capacity of cross-shaped and L-shaped multi-cavity CFSTSSCs were proposed. The results show that the error between the simplified equation and the FE result is less than 15%, indicating that the equations can provide reference for practical engineering applications.
“…On the other hand, the hoop coefficient, ξ, of the specimen decreases with the increase of the strength of concrete, which leads to the decrease of the restraint effect of multi-cavity steel tube on concrete. This further accelerates the decline rate of bearing capacity and reduces the ductility of the specimen (Wang, Zhou, et al, 2020).…”
Multi-cavity concrete-filled steel tube special shaped column (CFSTSSC) combines the excellent characteristics of multicavity steel tube and core concrete. CFSTSSC has the advantages of high bearing capacity, good ductility, and strong energy dissipation capacity. At present, accurate calculation methods for these kinds of structures are limited and research into crossshaped and L-shaped multi-cavity CFSTSSCs is not available. Therefore, the axial compression behavior of cross-shaped and L-shaped multi-cavity CFSTSSCs has been investigated, though experimental research and numerical simulation, in this study. First, axial compression tests were carried out on three cross-shaped and three L-shaped multi-cavity CFSTSSCs to analyze their failure modes, axial load-strain curve, ductility index, and ultimate bearing capacity. Then, finite element (FE) calculation models of cross-shaped and L-shaped multi-cavity CFSTSSCs were established. The FE models are in good agreement with the experimental results, which provides a foundation for further parameter analysis and failure mechanism study of special shaped columns. Finally, combining parameter analysis and limit equilibrium theory, equations for calculating the ultimate bearing capacity of cross-shaped and L-shaped multi-cavity CFSTSSCs were proposed. The results show that the error between the simplified equation and the FE result is less than 15%, indicating that the equations can provide reference for practical engineering applications.
“…Yang et al [28] researched the seismic behavior of four-legged square CFST latticed members under lateral cyclic loading and revealed that the fourlegged square CFST latticed specimens outperformed hollow steel ones in terms of hysteretic behavior. Wang et al [29] experimentally investigated the axial compressive performance of novel L-shaped and T-shaped concretefilled square steel tube (L/T-CFSST) columns and established formulae to calculate the axial compressive strength and stability bearing capacity of the L/T-CFSST columns accordingly. Shariati et al [30] presented a numerical investigation into the behavior of built-up concrete-filled steel tube columns under axial compression and indicated that the raise of concrete strength with greater cross section led to a higher load bearing capacity compared to the steel tube thickness increment.…”
The behavior of H-shaped honeycombed stub columns with rectangular concrete-filled steel tube flanges (STHCCs) subjected to axial load was investigated experimentally. A total of 16 specimens were studied, and the main parameters varied in the tests included the confinement effect coefficient of the steel tube (ξ), the concrete cubic compressive strength (fcu), the steel web thickness (t2), and the slenderness ratio of specimens (λs). Failure modes, load-displacement curves, load-strain curves of the steel tube flanges and webs, and force mechanisms were obtained by means of axial compression tests. The parameter influences on the axial compression bearing capacity and ductility were then analyzed. The results showed that rudder slip diagonal lines occur on the steel tube outer surface and the concrete-filled steel tube flanges of all specimens exhibit shear failure. Specimen load-displacement curves can be broadly divided into elastic deformation, elastic-plastic deformation, and load descending and residual deformation stages. The specimen axial compression bearing capacity and ductility increase with increasing ξ, and the axial compression bearing capacity increases gradually with increasing fcu, whereas the ductility decreases. The ductility significantly improves with increasing t2, whereas the axial compression bearing capacity increases slightly. The axial compression bearing capacity decreases gradually with increasing λs, whereas the ductility increases. An analytical expression for the STHCC short column axial compression bearing capacity is established by introducing a correction function (
w
), which has good agreement with experimental results. Finally, several design guidelines are suggested, which can provide a foundation for the popularization and application of this kind of novel composite column in practical engineering projects.
“…e confinement effect of external steel pipe changes the concrete from two-way stress state to three-way stress state, which can improve the compressive properties of concrete. e internal concrete can improve the buckling of steel pipe and ensure the full play of material properties [9][10][11].…”
Section: Introductionmentioning
confidence: 99%
“…Concrete-filled steel pipe has been widely used in ground buildings due to its high strength and good ductility [9,[11][12][13][14][15][16]. In recent years, some scholars have begun to propose the introduction of concrete-filled steel pipe into coal mine roadway support.…”
A large number of gas drainage pipes are obsoleted in the coal mine gas drainage system, and it causes serious waste. If concrete is poured into the discarded gas drainage pipes as components for underground roadway support, it is very significant for sustainable development of mine. Therefore, it is necessary to study the mechanical properties of the concrete-filled gas drainage steel pipe. Most frequently used gas drainage pipes are spiral welded steel pipe (SSP-I) and spiral external rib steel pipe (SSP-II). In this study, three different concrete-filled steel pipes are taken as the research object: SSP-I concrete-filled steel pipes, SSP-II concrete-filled steel pipes, and RSP concrete-filled ordinary round steel pipes. Through the axial compression test, the failure mode and relationship between stress-strain of concrete-filled steel pipes were obtained. Subsequently, the ultimate bearing capacity of three types of specimens was calculated based on the unified strength theory, limit equilibrium theory, and superposition theory. The test results show that both the SSP-I concrete-filled pipe columns and RSP concrete-filled pipe have good post-peak load-bearing capacity and ductility, and the second peak load reaches 70.38% and 81.92% of the ultimate load, respectively. The load-bearing capacity of SSP-II concrete-filled pipe columns is dropped sharply after bearing ultimate load, and the second peak load reaches only 36.47% of the ultimate load. The failure characteristics of concrete-filled gas drainage pipe columns show that the core concrete is compressed to powder and explain that the gas drainage pipe has fully exerted its restraint on the concrete. The FE method was used to simulate the compression test of three types of concrete-filled steel pipes, and the numerical simulation results show good agreement with the experimental results. Theoretical calculations show that the calculation of concrete-filled gas drainage pipe columns based on the superposition theory EC4-2004 is the closest to the measured value. Therefore, the EC4-2004 standard is recommended to calculate the ultimate bearing capacity of concrete-filled gas drainage pipe columns.
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