Study on Failure Performance of the Thin-Walled Steel-Reinforced Concrete Pier under Low Cyclic Loading
Abstract and Figures
Recently, the light-type pier can be easily observed in urban elevated roads and bridge structures. This type of pier is broadly used in the field of structural engineering. The Thin-Walled Steel-Reinforced Concrete Pier (TSRCP), as the typical pier of the light-type piers, shows a better mechanical performance than the conventional reinforced concrete pier due to the enhancement of the H-shape steel. In terms of the TSRCP, the designed parameters, including the depth–width ratio (DWR) and axial compression ratio (ACR), have been determined in this study as the concerned variables. Then, a low cyclic loading experiment is conducted based on the three test specimens to investigate the effects of the concerned variables on the failure of the specimens. Meanwhile, some comparative studies are carried out based on the failure processes and modes, critical loading values (cracking, yielding and ultimate state), strain and ductility. The obtained experimental results demonstrate that all specimens illustrate a bending failure mode under the vertical and horizontal low cyclic loadings. Furthermore, for the concerned variables, the increasing DWR will reduce the ultimate bearing capacity of the TSRCP but enhance the plastic deformation. For the ACR, the decrease positively affects the cracking load, further improving the ultimate bearing capacity; however, the deformation capacity will be restrained. Finally, Abaqus is adopted to model the failure processes of three specimens; the comparative study has been conducted based on the simulated and experimental results. After that, the effects of the concerned variables on the failure performances are discussed. Meanwhile, the horizontal ultimate bearing capacity calculated equation for the TSRCP was deduced and validated based on the experimental and simulated data; the verification proves that the proposed equation can obtain a good result. In this study, the complex calculated process of the original equation can be simplified, which not only provides a convenient and useful way to design and manufacture this type of component but can serve as a guideline for validating the practical engineering applications.
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... Nonlinear temperature changes not only affect a pier's alignment but also produce a large eccentric bending moment at the bottom of the pier that affects the bearing capacity of the pier [7][8][9]. Hence, studies of the effects of sunlight temperature differences on the alignment of such high piers [10][11][12][13] are urgently needed. ...
... The above analytical formula applies to both the calculation of pier top displacement along the bridge and the calculation of pier top displacement across the bridge under the measured sunlight temperature difference. When calculating the transverse displacement of the pier top, it is only necessary to exchange the position of the along-bridge parameter d i (d i0 ) and the transverse bridge parameter h i (h i0 ) in Formula (13). Furthermore, after calculating the longitudinal and transverse displacements of the pier top, the total displacement S of the pier top can be obtained by coupling these two displacements [40,41]. ...
Formulas for computing the line shape of a thin-walled hollow pier body based on structural characteristics and measured sunlight temperature difference are derived using an analytical algorithm. In a case study of the No. 5 pier of a newly constructed continuous beam bridge on a mountainous expressway of Guizhou Province in China, the pier top’s displacement calculated by the analytical algorithm, currently accepted code, and a FEM program were each compared to its measured values. Furthermore, the effects of sunlight temperature difference, pier height, and wall thickness on the line shape of the pier body were explored, and the results show that the calculation values from these formulas were closer to the measured values than the currently accepted code, with a maximum error of 0.507 mm, demonstrating that the formulas have a more dependable result, higher precision, and more specific applicability. Thus, the algorithm provides a better method for the line shape calculation and construction control of thin-walled hollow piers because it can accurately account for sunlight temperature differences and pier height.
... Reinforced concrete (RC) is a composite material composed of rebar and concrete. It takes advantage of the positive characteristics of both of its components and is widely used in roads, bridges, ports and offshore infrastructure [1][2][3][4][5]. As noted in previous studies, a large number of RC structures do not reach their predetermined design service life, but rather, fail due to insufficient durability [6][7][8][9][10][11][12][13][14][15]. ...
Soda residue soil (SRS) is a man-made engineering foundation soil formed by soda residue; it is mainly distributed in coastal areas in China. SRS is rich in a variety of corrosive salts, among which the concentrations of chloride ions are about 2–3 times that of seawater. These highly concentrated chloride ions migrate and diffuse in reinforced concrete (RC) structures built on coastal SRS through multiple transport mechanisms. However, current research on the durability of RC structures exposed to the coastal SRS environment has not led to the publication of any reports in the literature. SRS may be classified by analyzing the quantitative relationships among the corrosive ions it contains. In this paper, the deterioration of RC structures due to the corrosive saline-soil environment in China is discussed, and advances in RC structure durability under such circumstances are reviewed. Our findings show that a corrosive environment, especially when this is a result of coastal SRS, has a significant influence on the deterioration of RC structures, greatly threatening such buildings. A series of effective measures for enhancing the durability of RC structures in saline soil, including improvements in concrete strength, reductions in the water–binder ratio, the addition of mineral admixtures and fiber-reinforcing agents, etc., could provide a vital foundation for enhancing the durability of RC structures which are at risk due to coastal SRS. Vital issues that must be investigated regarding the durability of RC structures are proposed, including the transport mechanism and a prediction model of corrosive ions, dominated by chloride ions (Cl−), in SRS and RC structures, the deterioration mechanism of RC materials, a long-term performance deduction process of RC components, durability design theory, and effective performance enhancement measures. The findings of this paper provide some clear exploration directions for the development of basic theories regarding RC structure durability in coastal SRS environments and go some way to making up for the research gap regarding RC structure durability under corrosive soil environments.
In this study, with the aim of investigating the confinement behavior and stress–strain response of concrete columns strengthened with carbon textile reinforced concrete (CTRC) under a uniaxial load, a total of 20 column specimens with square cross-sections were cast and subjected to monotonic axial compression. Next, the effects of the number of textile layers, stirrup reinforcement ratio, concrete strength and short fibers on the efficiency of CTRC confining system were evaluated. The experimental results indicated that the CTRC-confined columns obtained a maximum improvement of up to 67.3% in bearing capacity and 65.2% in displacement ductility compared to the un-strengthened reference columns, and exhibited a more significant ductile failure characteristic. Moreover, the bearing capacity and displacement ductility of the confined columns were characterized by increasing with an increase in the number of textile layers and stirrup ratio, and a decrease in the concrete strength. The short fibers mixed in the strengthening layers also made a beneficial contribution to the bearing capacity and displacement ductility, particularly to the cracking load of the confined columns. Finally, a semi-empirical model was proposed to predict the axial stress and strain of concrete column specimens strengthened with CTRC based on the experimental results and theoretical analysis. The results calculated by the proposed model were evidenced to be fundamentally consistent with the experimental results. Therefore, the proposed model in this study could effectively predict the stress–strain response of square RC columns confined with CTRC composites.
In order to combine the advantages of steel reinforced concrete column, high-strength concrete and precast structures, a novel steel reinforced high-strength concrete composite column is presented in this paper. With the aim to explore the seismic performance of this composite column, three column specimens were designed and tested under cyclic loading. The cyclic behavior of test specimens was evaluated through the failure patterns, hysteresis loops, skeleton curves, energy dissipation, stiffness degradation and displacement ductility. The test results indicated that the shear failure could be found in the specimens subjected to low aspect ratio, and the rest specimens all failed in flexural-shear failure. The initial stiffness and bearing capacity decreased with the increasing of aspect ratio, and the energy dissipation capacity and displacement ductility increased with the increasing of aspect ratio.
In this paper, the confinement performance and stress–strain response of reinforced concrete (RC) with corroded reinforcement were studied, with consideration given to such key parameters as corrosion levels, size effect, stirrup configurations, and effects of synchronized corrosion of the stirrups and longitudinal reinforcements. A total of 29 square RC columns, which had been corroded through accelerated corrosion tests, were examined using axial compression evaluations. The theoretical corrosion levels of the stirrups ranged from 0% to 20%. The column size coefficient (defined as the volume ratio of the corroded columns to the standard prism) varied from 1.0 to 4.17, and the spacings of the stirrups ranged between 50 mm and 125 mm. The test results revealed that the confinement behaviors were significantly affected by the severity of the corrosion of the stirrups, including the failure mode, bearing capacity, and deformability. The highest reductions in load and displacement ductility were found at a theoretical corrosion level of 20%, up to 22.37% and 77.05%, respectively. Meanwhile, the confinement performance was also found to be influenced by the stirrup spacings and specimen sizes. It was found that although the corrosion of stirrup was much higher than that of longitudinal reinforcement, the corrosion of longitudinal reinforcement would still less affect the compressive performance of the RC column. The semiempirical and semi-theoretical formulas for calculating the compressive strength and corresponding strain were proposed based on the experimental data and theoretical analysis results. Then, an optimal stress–strain prediction model for concrete confined with corroded stirrups was successfully established. The proposed model showed a good correlation with the experimental data when compared with the existing prediction model.
Steel reinforced concrete columns are the key vertical load-bearing members in the frame composite structures of super high-rise buildings. The steel sections and steel ratios of these columns are the major factors affecting their seismic performance. In this paper, four large steel reinforced high-strength concrete (SRHC) columns were designed. The influences of closed and open steel sections on the seismic performance of SRHC columns with different steel ratios were analyzed. The test results show that the SRHC columns with closed steel sections had plumper hysteresis loops, a higher and more stable bearing capacity, and greater deformation and energy dissipation capacities than the columns with open steel sections. The influences of the steel ratio on the plumpness of the hysteresis loops, residual deformation and energy dissipation capacity of the columns with open steel sections were greater than those of the columns with closed steel sections. The fiber-based method was adopted to predict the F-Δ curves and N-M interaction curves of the SRHC columns with closed and open steel sections. The calculated results show good agreement with the test results, and the experimental results can provide evidence for the seismic design of SRHC columns with both closed and open steel sections.
The lack of seismic capacity of piers leads to bridge collapse in recent earthquakes, such as the 1994 Northridge (USA), 1995 Kobe (Japan) and 2008 Wenchuan (China) earthquakes. For precast bridge piers, the performance of pier connection determines the seismic capacity of the whole bridge. Therefore, a new connection between precast bridge column and footing using ultra-high performance concrete (UHPC) is developed in this paper. The precast column and footing are connected by longitudinal rebars of the column and the footing anchored into the UHPC-filled cage. The connection allows force to be transferred from the column rebars to UHPC, then to the footing rebars by bond effects. To investigate the seismic behavior of precast bridge piers with this new UHPC connection, cyclic tests with two large-scale (1:2.5) models are carried out. One is the precast reinforced concrete (RC) specimen using the proposed new connection, and the other is the cast-in-place (CIP) RC reference. The results show that the failure modes of the specimens are similar, both denoted by crushing of the core concrete above the connection segment. No obvious damage is observed in the connection region, which demonstrates that the precast bridge pier with the proposed connection is emulative of the CIP pier. Furthermore, a finite element model is developed to simulate the cyclic response of the precast column with proposed connection. The deviation between the calculated and measured force–displacement relationships is about 5%, which indicates that the numerical model used herein can be effective to capture the performance of the precast pier with new UHPC connection.
A computational model for studying the mechanical performance of steel-concrete columns under combined torsion is established via ABAQUS. The model is validated by experimental results. Through numerical simulations, the influence of the axial load ratio, torsion-bending ratio, concrete strength, steel ratio, longitudinal reinforcement ratio, stirrup ratio, and shear-span ratio on the torsional behaviour of steel-concrete columns is comprehensively investigated. The initial torsion stiffness and ultimate torsion strength of the column increase with increasing concrete strength and decreasing shear-span ratio. The parameters in descending order of influence on the ultimate torsion strength are steel ratio, torsion-bending ratio, stirrup ratio, longitudinal reinforcement ratio, and axial load ratio. Furthermore, the seven parameters in descending order of influence on the ductility coefficient are the steel ratio, shear-span ratio, concrete strength, axial load ratio, stirrup ratio, torsion-bending ratio and longitudinal reinforcement ratio.
This paper aims to develop two kinds of innovative precast steel reinforced concrete columns, which are partially precast steel reinforced concrete (PPSRC) columns and hollow precast steel reinforced concrete (HPSRC) columns. Both the two kinds of composite columns have precast reactive powder concrete (RPC) shells, and the PPSRC column has a cast-in-place column core. In this paper, a series of cyclic loading tests on 10 column specimens subjected to combined static axial loading and cyclic lateral loading were carried out to explore their seismic performances. All specimens were evaluated by the failure modes, hysteresis characteristics, strength and stiffness degradation, energy dissipation capacity and ductility. The effects of section shape, stirrup spacing, axial compression and concrete strength of cast-in-place inner-part were investigated in details. The experiment results indicated that the PPSRC columns exhibited more satisfactory seismic behavior than the HPSRC columns in terms of hysteretic behavior, strength degradation, ductility and energy dissipation, while their bearing capacities were almost identical under low axial compression. Steel fibers could effectively prevent the cracked concrete from spalling, therefore, the encased steel shape was efficiently confined by the surrounding concrete during the entire test process. Higher stirrup ratio and lower axial compression of the column leaded to more satisfactory energy dissipation capacity, stiffness degradation and higher ductility. Based on the plastic stress theory, the seismic bending moment capacity analysis was conducted, and the results obtained form the formulas agreed well with those from the experiments.