Infill Steel Research Articles

Transverse compressive behavior of plain and polypropylene fiber-reinforced concrete infilled steel tubes as hybrid steel-concrete nodes for discrete reticulated shell structures

This study investigates using concrete infilled steel tubes as hybrid nodes for discrete reticulated shell structures under compressive loading transverse to the tube axis. Three configurations were tested: empty, plain concrete infilled and polypropylene fiber-reinforced concrete infilled steel tubes. Displacement-controlled loading was applied through welded steel plates. Simplified beam theory models and nonlinear finite element analysis were used to evaluate the structural behavior. The concrete infilled steel tube specimens had higher stiffness and load-bearing capacity than the empty ones. The structural behavior of the concrete infilled specimens could be split into pre- and post-split-tensile cracking phases. No significant difference was found between the plain and fiber-reinforced concrete specimens under loads up to 1500 kN, which was the load limit of the testing machine. An additional fiber-reinforced concrete specimen, tested on a higher capacity machine, had a load-bearing capacity of 2400 kN and exhibited ductile failure.

Mechanical properties of geopolymer recycled concrete infilled steel tubes with three sectional types

The steel tubes with geopolymer recycled concrete (GRC) infill are actively seeking environmentally friendly and low-carbon building materials as alternatives in the process of promoting sustainable development, maximizing the use of waste materials and resources, and reducing consumption of natural resources and environmental pollution. In this paper, three types of steel tube specimens with GRC infill were proposed, i.e., the geopolymer recycled concrete-filled steel tube (GRCFST), geopolymer recycled concrete-filled double skin steel tube (GRCFDST), and geopolymer recycled concrete-filled double section steel tubes (GRCFDSST). These GRC-steel tube structures were tested under axial compressive loading, and the influence of some crucial factors on bearing capacity, ductility and strain distribution of specimens was considered, such as the slag content, and the types of steel tube section and the replacement rate of recycled aggregate. The experimental results show that the steel tube can provide effective confinement for geopolymer recycled concrete and thus compensate for the adverse effect induced by recycled aggregate. The slag content has less effect on the bearing capacities of the GRCFDSST specimen compared with the GRCFST and GRCFDST specimens due to the stronger confinement effect of the former. The ductility of GRCFDSST specimens is better than the other steel tube specimens under the same parameter conditions. This study, building on existing literature, provides new insights and design recommendations for the mechanical performance of concrete-filled steel tube structures by using geopolymer recycled concrete as a filling material.

Study on the Shear Behaviors and Capacity of Double-Sided Concrete-Encased Composite Steel Plate Shear Walls by Experiment and Finite Element Analysis

Concrete-encased composite plate shear walls (C-PSW/CEs) can realize the in-plane shear yielding of infill steel plate with the buckling restrained from the concrete panel. Concrete panels also additionally resist portions of lateral loading in C-PSW/CEs, whereby the shear stiffness and strength of the C-PSW/CE are improved. However, research on the in-plane behaviors of concrete panels and the interactions between structural elements is limited. In this paper, the mechanical characteristics and the interactions and the shear resistances of C-PSW/CEs with double-sided concrete encasements were studied. First, the effects of concrete thickness on the damage process, steel plate buckling, and shear resistances of C-PSW/CEs under lateral loading were tested. Then, finite element analyses of the internal forces of the horizontal and inclined cross-sections and the shear force–drift ratio responses of C-PSW/CEs were undertaken with the extended finite element method (XFEM) to simulate the cracking behaviors of concrete panels. A shear force–drift ratio model based on mechanics was developed by considering the lateral load resistances of concrete panels and their effects on steel plates in C-PSW/CEs.

Topology optimization of the flat steel shear wall based on the volume constraint and strain energy assumptions under the seismic loading conditions

In structural engineering systems, shear walls are two-dimensional vertical elements designed to endure lateral forces acting in-plane, most frequently seismic and wind loads. Shear walls come in a variety of materials and are typically found in high-rise structures. Because steel shear walls are lighter, more ductile, and stronger than other concrete shear walls, they are advised for usage in steel constructions. It is important to remember that the steel shear wall has an infill plate, which can be produced in a variety of forms. The critical zones in flat steel shear walls are the joints and corners where the infill plate and frame meet. The flat infill plate can be modified to improve the strength and weight performance of the steel shear walls. One of these procedures is Topology Optimization (TO) and this method can reduce the weight and also, increase the strength against the cyclic loading sequences. In the current research paper, the TO of the infill steel plate was considered based on the two methods of volume constraint and maximization of strain energy. Four different volumes (i.e., 60%, 70%, 80%, and 90%) were assumed for the mentioned element in the steel shear wall. The obtained results revealed that the topology configuration of CCSSW with 90% volume constraint presented the highest seismic loading performance. The cumulated energy for this type of SSW was around 700 kJ while it was around 600 kJ for other topology optimization configurations.

Seismic behavior of steel frame infilled with wall-panels connected by sliding joint

This paper presents the experimental study on the seismic performance of steel frame structures equipped with novel sliding connection joints and wall panels reinforced by the fiber-reinforced polymer (FRP) sheet. Based on the proposed sliding connection joints and reinforced wall panels, five specimens were tested under cyclic loading. The bearing capacity, ductility performance, and energy dissipation capacity of the specimens were analyzed. Experimental results proved that the failure modes of all specimens were the crack of the panels and the column end buckling. And the infill wall panels had a significant supporting effect on the frame. The sliding joint and FRP sheet can enhance the collaborative ability, strength, and cumulative energy dissipation of the infill steel frame. Finally, a simplified calculation method is developed to evaluate the load-bearing capacity of the infill steel frame, considering the effect of the panels. The results proved the method owned acceptable accuracy, which could direct the practical design of the high-rise structure buildings.

Experimental study on CFRP-strengthened bolted splicing modular steel plate shear wall

The seismic performance of the steel plate shear wall (SPSW) structure will be weakened by the modular splicing of the infill steel plates. To address this, carbon fiber reinforced plastic (CFRP) was used to strengthen its splicing joints. First, the specimens of CFRP-strengthened bolted joints with different CFRP laying methods were tested in uniaxial tensile control, and the corresponding design method was proposed. Next, this method was introduced into the vertical splicing joints of modular SPSWs. Three 1/3-scale SPSW specimens, with and without CFRP-strengthened modular SPSW and complete SPSW, were tested under quasi-static cyclic loading. The failure modes and hysteresis performance of the three structures were compared, and the effects of using CFRP-strengthened splicing joints on various properties of the SPSW structure were investigated. The force mechanism of the CFRP-strengthened bolted splicing modular SPSW structure was further investigated by finite element (FE) analysis. The results indicated that the CFRP strengthening vertical splicing joints can effectively reduce the stress concentration around the hole walls of the infill steel plate, improve the performance loss of wall plates due to modular segmentation, and reduce slippage of splicing joints and out-of-plane deformation amplitude of wall plate. The CFRP-strengthened vertically bolted modular SPSWs increased the stiffness and load capacity of the structure, with yield bearing capacity and stiffness increased by 11.40% and 19.57% compared with those of the vertically bolted modular SPSW, respectively.

Mechanisms of plasticity development and energy dissipation on concrete-encased steel plate shear wall with boundary steel frame under cyclic loading

Steel frame infilled with composite plate shear wall (SF-CPSW) is an efficient lateral load resisting structure with significant ductility and energy dissipation capacity. In this paper, CPSW comprises the infill steel plate, encased concrete panel and headed studs. The steel frames (SFs) are expected to sustain the vertical load, while as the boundary members of the CPSW, they also influence the lateral behaviors of structure. However, the research on the interactions or plasticity development of SF-CPSW is limited. Thus, its energy dissipation mechanism is unclear to date. This paper conducts finite element analyses on the hysteresis performance and energy dissipation mechanism of SF-CPSW structure under cyclic loading. The hysteresis and skeleton of lateral load-drift ratio responses, distributions and developments of internal forces, stresses and strains and the energy assignments are studied to reveal the mechanisms of lateral load-resisting and plasticity development of SF-CPSW. The effects of steel plate thickness, beam cross-section, column cross-section and concrete panel thickness on the hysteresis performance and energy assignment are investigated to propose the energy dissipation mechanism and associated design methods. The results indicate that the energy dissipation of SF-CPSW is governed by the plastic shearing of infill steel plate and beam web due to the shear force transfers and bending restraints from CPSW to the steel frame. Besides, the columns resist portions of lateral load under such interactions. The structural energy dissipation should develop successively by the shear yielding of steel plate, the shear yielding of beam and column, the flexural yielding of beam, the plastic buckling of steel plate and the flexural yielding of column. As the major members for energy dissipation, the yield shear strength of beam should be higher than 27.5% yield shear strength of infill steel plate.

Development of numerical model capturing cyclic behavior of Two-Side clamped infill plates

This study aims to propose a simple numerical model methodology for two-side clamped infill steel plates with various aspect ratios, slenderness ratios and even different steel grades. The modeling element constructed using the methodology expects to be directly implemented into computer structural software for nonlinear time-history analyses of structures employing two-side clamped infill plates. The suggested model is constructed with their force–displacement relation including nonlinear and cyclic effects which can be defined by modeling parameters evaluated from empirical equations. The empirical equations are developed using regression analyses to agree with the parametric analysis results with detailed finite element models of two-side clamped infill plates. A proposed numerical model including the hysteretic characteristics was validated by comparison with existing experimental results conducted by other studies. It is confirmed to utilize the proposed numerical model that can accurately represent cyclic behavior over entire response ranges including buckling, tension field action representing the post-buckling behavior, and fracture of steel plates.

Study on the shear mechanism and resistance of single-side concrete-encased composite plate shear wall

Concrete-encased composite plate shear walls (C-PSW/CEs) are effective structural elements for the lateral load-resisting. With the restraints from concrete panels and headed studs, the shear yielding of infill steel plate can be realized. In service, concrete panel can also provide a significant shear resistance to C-PSWCEs. Especially for the single-side concrete-encased ones, the post-buckling strength for the local buckling of steel plate can be utilized in ductility. However, research on the in-plane behavior of concrete panel or the post-buckling behavior of steel plate in the single-side C-PSW/CE is limited. In this paper, the shear behavior of single-side C-PSW/CE under lateral loading was studied by experiment and finite element analysis. The damage process and shear resistance of C-PSW/CE with different concrete thicknesses were tested. The extended finite element method (XFEM) was employed in the finite element model (FEM) to simulate the cracking of concrete panel. The internal forces in the horizontal and inclined cross sections of steel plate and concrete panel and in the pure shear zones and diagonal tension fields of steel plate were investigated to reveal the shear mechanisms of C-PSW/CE. Based on the parametric analysis results, formulas for the shear stiffness and yield shear force and a mechanics-based model for the shear force-drift ratio response of single-side C-PSW/CE were proposed.

Assessment of cyclic behavior and performance of hybrid linked-column steel plate shear wall system

An innovative hybrid linked columns steel plate shear wall (HLCS) system provided, and its cyclic behavior and energy absorption are investigated by finite element method in this study. The objective of the designed HLCS system was to reduce or possibly prevent damage to the SPSW at low and medium seismic levels by focusing the seismic damage to interchangeable link beams (the energy dissipation components of the presented HLCS system). In this study, the cyclic behavior and energy dissipation of HLCS systems were investigated using numerical methods. To evaluate the hysteresis behavior and energy absorption of the proposed HLCS system, parametric studies were performed. Also, the accuracy of finite element models was evaluated by comparing test results that showed the good accuracy of finite element models in predicting the specimens' hysteresis behavior and failure modes. Due to the failure mechanisms, the coupling ratio amounts meaningfully affect the onset of the first surrender mechanism between the infill steel plate and link beams. In general, by increasing the number of link beams in the floor, the ultimate shear force to the weight ratio of the structure was increased. Also, the type of beam in terms of flexural and shear behavior did not significantly affect the ratio of base shear force to the structure weight. The proposed HLCS system has increased the ratio of base shear force to the weight by an average of 4%–27%, indicating that this system is economically comparable to the SPSW systems. Moreover, the energy dissipation in the HLCS system exhibited a 14%–91% enhancement compared to the SPSW system.

Evaluation and Numerical Investigations of the Cyclic Behavior of Smart Composite Steel-Concrete Shear Wall: Comprehensive Study of Finite Element Model.

The composite shear wall has various merits over the traditional reinforced concrete walls. Thus, several experimental studies have been reported in the literature in order to study the seismic behavior of composite shear walls. However, few numerical investigations were found in the previous literature because of difficulties in the interaction behavior of steel and concrete. This study aimed to present a numerical analysis of smart composite shear walls, which use an infilled steel plate and concrete. The study was carried out using the ANSYS software. The mechanical mechanisms between the web plate and concrete were investigated thoroughly. The results obtained from the finite element (FE) analysis show excellent agreement with the experimental test results in terms of the hysteresis curves, failure behavior, ultimate strength, initial stiffness, and ductility. The present numerical investigations were focused on the effects of the gap, thickness of infill steel plate, thickness of the concrete wall, and distance between shear studs on the composite steel plate shear wall (CSPSW) behavior. The results indicate that increasing the gap between steel plate and concrete wall from 0 mm to 40 mm improved the stiffness by 18% as compared to the reference model, which led to delay failures of this model. Expanding the infill steel plate thickness to 12 mm enhanced the stiffness and energy absorption with a ratio of 95% and 58%, respectively. This resulted in a gradual drop in the strength capacity of this model. Meanwhile, increasing concrete wall thickness to 150 mm enhanced the ductility and energy absorption with a ratio of 52% and 32%, respectively, which led to restricting the model and reduced lateral offset. Changing the distance between shear studs from 20% to 25% enhanced the ductility and energy absorption by about 66% and 32%, respectively.

Modelling of Cyclic Load Behaviour of Smart Composite Steel-Concrete Shear Wall Using Finite Element Analysis

In recent years, steel-concrete composite shear walls have been widely used in enormous high-rise buildings. Due to their high strength and ductility, enhanced stiffness, stable cycle characteristics and large energy absorption, such walls can be adopted in auxiliary buildings, surrounding the reactor containment structure of nuclear power plants to resist lateral forces induced by heavy winds and severe earthquakes. The current study aims to investigate the seismic behaviour of composite shear walls and evaluate their performance in comparison with traditional reinforced concrete (RC) walls when subjected to cyclic loading. A three-dimensional finite element model is developed using ANSYS by emphasising constitutive material modelling and element type to represent the real physical behaviour of complex shear wall structures. The analysis escalates with parametric variation in reinforcement ratio, compressive strength of the concrete wall, layout of shear stud and yield stress of infill steel plate. The modelling details of structural components, contact conditions between steel and concrete, associated boundary conditions and constitutive relationships for the cyclic loading are explained. The findings of this study showed that an up to 3.5% increase in the reinforcement ratio enhanced the ductility and energy absorption with a ratio of 37% and 38%, respectively. Moreover, increasing the concrete strength up to 55 MPa enhanced the ductility and energy absorption with ratios of 51% and 38%, respectively. Thus, this improves the contribution of concrete strength, while increasing the yield stress of steel plate (to 380 MPa) enhanced the ductility (by a ratio of 66%) compared with the reference model. The present numerical research shows that the compressive strength of the concrete wall, reinforcement ratio, layout of shear stud and yield stress of infill steel plate significantly affect ductility and energy absorption. Moreover, this offers a possibility for improving the shear wall’s capacity, which is more important.

Numerical Study on Steel Plate Shear Wall with Slit having Rectangular Opening

Steel plate shear wall with slit (SPSWS) is one of lateral load resisting systems that can be used in new buildings as well as in upgrading existing structures. It possesses efficient energy dissipation capacity and good ductility as a result of the installed slits within the infill steel plate. Cutouts might be required to let utility lines and other services pass through, for weight reduction and/or aesthetics. In this study, the effect of introducing rectangular cutout on SPSWS system will be examined under cyclic loading using finite element method. The paper considered the buckling load, ultimate bearing capacity, energy dissipation capacity, initial stiffness and stiffness degradation, ductility, and cracking patterns of the SPSWS. The parametric study includes: the effect of the presence of the vertical slits, thickness of steel plate and presence of edge stiffeners. The result showed that the presence of the vertical slits has highly minimized the negative effect of the rectangular cutout on the desired hysteretic behavior of the wall. Buckling resistance of slit wall with edge stiffeners tends to increase with cutting rectangular opening while it declines when the rectangular cutout is introduced to slit wall without edge stiffeners. It was also found out that when cutting a rectangular opening in the slit wall system, edge stiffener is more influential parameter than thickness of plate.

Semi-supported Steel Plate Shear Wall with Oblique Sides

This paper presents a new configuration for semi-supported steel plate shear walls to increase their efficiency. For this purpose, the infill steel plate is proposed to be a trapezoidal shape instead of a rectangular one. To find the most efficient inclination angle of lateral sides, a numerical parametric study was conducted. Five different values of inclination angle including 60, 75, 90, 105, and 120 degrees were considered. Furthermore, two thicknesses of 1.75 and 2.00 mm were considered for the steel plate. The area of the steel plate was the same for all the models. The models were analyzed using finite element software ABAQUS. Both geometric and material nonlinearity have been considered. To validate the finite element modeling, the available experimental results were used. According to the results, comparing to the wall with rectangular plate, the inclination angle of 60° increases the ultimate lateral strength and stiffness of the 1.75 mm-thick walls by 46% and 66%, respectively. Furthermore, a simple approximate model is presented to calculate the load-deformation response of the proposed wall using SAP 2000 program. Despite the simplicity of the method, the results were in good agreement with the results of ABAQUS.

Seismic behavior of hollow-core infilled steel frames; an experimental and numerical study

This study describes an experimental program designed to investigate the influence of the presence and orientation of hollow-core wall panels as well as beam to column connection rigidity on the seismic performance of steel frames infilled with hollow-core wall units. For this purpose, four half-scale, single-story, and single-bay specimens, including three infilled steel frames and one bare moment frame, were subjected to cyclic lateral loading. The bare steel frame and two infill specimens had rigid connections, while the last one had pinned connections. One of rigid connections specimen was constructed with hollow-core wall panels placed vertically, whereas the other was fabricated with wall panels with the horizontal core. The experimental results indicated that the vertical placement of hollow-core wall units controlled structural damage and improved the seismic performance through the rocking mechanism within the steel frame. In addition, the strength, stiffness, and energy dissipation capacity of the infilled pinned connections frame were less than those in rigid connections specimen. In another part of this study, a parametric study was conducted with finite element method using ABAQUS software. The parametric nonlinear analyses study revealed that the infilled frames with hollow-core wall panels placed vertically had less initial stiffness and more strength than those with horizontal core panels. On the other hand, the initial stiffness and strength of the infilled steel frame, bare steel frame, and infill contribution were reduced by the decrease in the rigidity of the steel frame connections, regardless of infill aspect ratio and the relative stiffness of the hollow-core panels to the surrounding steel frame.

Cyclic behavior of semi-rigid steel frame infilled with damping wall panels

Semi-rigid connected steel frame is characterized by excellent displacement ductility and energy dissipation capacity, while detrimental infill-frame interaction from the traditional infill would be a key role in seismic behaviors for such steel frames and may damage both infill and steel frame. In this study, the solution to partition the infill with low-strength mortar sliding joints and uncouple the infill from the surrounding frame by flexible connections for the semi-rigid steel frames is presented. Three specimens designed in this context were examined experimentally and numerically. The test results show that the frame with low-strength sliding joints and flexible connections behaves similarly to the bare steel frame, and improves the energy dissipation capacity by about 19.83%. Unlike the semi-rigid steel frame with traditional infill, significant crack of the infill or local stress concentration on the columns is undetected even at a drift ratio of 3.33% in the proposed infilled steel frame. Parametric analysis results confirm that the friction factor of the low-strength sliding joints is the key parameter to improve the lateral bearing capacity of the infill system.

Performance of repaired steel plate shear wall with earthquake-induced damage

To investigate the repair method of damaged steel plate shear wall in a steel frame, a scaled specimen was designed and tested under a two-phase pseudo-static loading. The damaged infilled steel plates were replaced with new steel plates between the two loading phases. The test results showed that after replacing the damaged infilled plates, the stiffness of the specimen increased. The bearing capacity was 577.3 kN, with a ductility of 3.5. The seismic performance of the repaired specimen was favorable. Replacing the infilled plate was an effective repair method for the steel plate shear wall structure while the columns were still in good integrity. To ensure a reliable post-earthquake performance of the boundary frame and an easy repair for the steel plate shear wall, the plastic development of the boundary column was investigate. By introducing the damage criterion into the finite element (FE) model, the stress redistribution caused by the damage of the infilled steel plate was considered. The shear force of the column at different lateral displacement, especially in the inelastic phase, was obtained. The yielding and damage state of the boundary column can be determined from the proportion of sustained shear force of the column at different displacements.

Axial Behavior of Concrete Filled-steel Tube Columns Reinforced with Steel Fibers

Concrete filled steel tube (CFST) columns are being popular in civil engineering due to their superior structural characteristics. This paper investigates enhancement in axial behavior of CFST columns by adding steel fibers to plain concrete that infill steel tubes. Four specimens were prepared: two square columns (100*100 mm) and two circular columns (100 mm in diameter). All columns were 60 cm in length. Plain concrete mix and concrete reinforced with steel fibers were used to infill steel tube columns. Ultimate axial load capacity, ductility and failure mode are discussed in this study. The results showed that the ultimate axial load capacity of CFST columns reinforced with steel fibers increased by 28% and 20 % for circular and square columns, respectively. Also, the circular CFST columns exhibited better ductility than the square CFST columns due to better concrete confinement. Circular and square CFST columns with steel fibers showed improved ductility by 16.3% and 12%, respectively. The failure mode of the square CFST columns were local buckling which occurred near the end of columns, while, for the circular CFST columns, local buckling occurred near the mid-height. Also, the study involved sectional analysis that captured the behavior of CFST columns very well. The sectional analysis showed that increasing steel fiber content to 2% increased the axial load capacity by 51 and 38% for circular and square CFST columns, respectively. Furthermore, sectional analysis showed that doubling section size increased axial load capacity by approximately 4 and 5 times for circular and square columns, respectively.

Confinement Effect and Efficiency of Concentrically Loaded RACFCST Stub Columns.

Recycled aggregate concrete-filled steel tubular (RACFST) columns are widely recognized as efficient structural members that can reduce the environmental impact of the building industry and improve the mechanical behavior of recycled aggregate concrete (RAC). The objective of this study is to investigate the behavior of recycled aggregate concrete-filled circular steel tubular (RACFCST) stub columns subjected to the axial loading. Three-dimensional finite element (FE) models were established using a triaxial plastic-damage constitutive model of RAC considering the replacement ratio of recycled aggregates. The FE analytical results revealed that the decreased ultimate bearing capacity of RACFCST stub columns compared with conventional concrete infilled steel tubular (CFST) columns was mainly due to the weakened confinement effect and efficiency. This trend will become more apparent with the larger replacement ratio of recycled aggregates. A practical design formula of the ultimate bearing capacity of RACFCST stub columns subjected to axial load was proposed on the basis of the reasonably simplified cross-sectional stress nephogram at the ultimate state. The derivation process incorporated the equilibrium condition and the superposition theory. The proposed equation was evaluated by comparing its accuracy and accessibility to some well-known design formulae proposed by other researchers and some widely used design codes.

Shear force demand for headed stud of composite plate shear walls‐concrete encased under cyclic loading

SummaryIn composite plate shear walls‐concrete encased (C‐PSW/CE), the headed studs are used to anchor concrete panels on both sides of the infill steel plate and make them resist lateral load together. The finite element models of C‐PSW/CE are developed and validated by testing three C‐PSW/CE specimens under cyclic loading. The responses of the components in C‐PSW/CE under cyclic loading are simulated by finite element method. The effects of the number of headed studs, stud diameter, concrete panel thickness, infill steel plate thickness, and wall aspect ratio on the shear force of headed studs are studied. The equation is proposed to evaluate the shear force demand of headed studs in C‐PSW/CE under cyclic loading using the numerical results. The shear force demand of headed studs increases with decreasing the number of headed studs and wall aspect ratio, increasing the stud diameter, and increasing the thicknesses of concrete panel and infill steel plate. Compared with the shear force demand of headed studs in C‐PSW/CE under monotonic loading, it is recommended that the shear force demand of headed studs in design of C‐PSW/CE in high seismic regions adopts the larger of shear force demands of headed studs under monotonic and cyclic loadings.