Concrete Steel Research Articles

Impact response of SCS sandwich slabs with ultra-high performance concrete: Failure mechanism and influence of shear connector configuration

In the typical steel-concrete-steel (SCS) sandwich structure, the normal-strength concrete core fills the external steel skeleton. This paper describes a program of drop-weight tests and finite element investigations on reduced-scale SCS sandwich slabs with ultra-high performance concrete (UHPC) core material as a novel protective layer construction. Test results demonstrated that the steel-ultra-high performance concrete-steel (SUHPCS) sandwich slabs were adequate for forming enhanced dynamic resistance through the high strength of UHPC and tensile stiffening membrane of the steel skins. Also, this construction was found to perform a highly ductile behavior and sustain obvious bulges without penetration through the whole slab. Precise finite element models for sandwich slabs under impact loading conditions were established and the simulated time histories were verified against the test data. Furthermore, a parametric study of sandwich slabs designed with different configurations of shear connectors was subjected to a spherical hammer weighing 540 kg dropping from the height of 5 m. The simulation results showed that the failure mode of SUHPCS sandwich slab changed with various degrees of composite interaction. Moreover, a theoretical methodology was proposed to classify the failure mode involving stiffness, flexural and punching resistances. SUHPCS sandwich slabs with a reasonable layout of shear connectors were found to provide a means for effective energy absorption against severe impact attacks.

A Building Information Modeling-Based Life Cycle Assessment of the Embodied Carbon and Environmental Impacts of High-Rise Building Structures: A Case Study

High-rise buildings represent technological, urban, and life-style trends of the modern urban landscape, yet there are limited data regarding their embodied carbon and environmental impacts, particularly when compared to low- or mid-rise buildings. Given that the projected growth of the global urban population by 2050 requires cities with higher density and potentially a greater number of high-rise buildings, it is crucial to develop a clear understanding of the embodied carbon and environmental impacts of high-rise buildings. The primary structural materials used in high-rise buildings are reinforced concrete and structural steel. As of today, over 99% of tall buildings’ structures are built from those two materials. This article utilizes a building information modeling (BIM)-based life cycle assessment (LCA) in Revit and Tally to examine the embodied carbon and environmental impacts of an actual high-rise building structure case study in Chicago that uses a hybrid concrete steel structure. The results show that the embodied carbon and environmental impacts of the high-rise building structure are dominated by the impacts of the product stage in the building’s life cycle and by concrete being the main structural material. Specifically, this study reveals that concrete constitutes a substantial 91% share of the total mass of the building structure, with a 74% contribution to the life cycle global warming potential, 53% to the acidification potential, 74% to the eutrophication potential, 74% to the smog formation potential, and 68% to the non-renewable energy usage. On the other hand, steel accounts for 9% of the building’s structure mass, estimated to constitute 26% of the global warming potential, 47% of the acidification potential, 26% of the eutrophication potential, 26% of the smog formation potential, and 32% of the non-renewable energy usage.

Theoretical solution for bond-slip behavior of composite structures consisting of H-shape beam and concrete based on experiment, numerical simulation, and theoretical derivation

This paper presents a theoretical solution for bond-slip behavior of SRC interface based on experiment, numerical simulation, and theoretical derivation. Push-out tests of five specimens were firstly carried out, based on which, the simplified bond-slip model was proposed. The specimen was fabricated using the Q345H-shape steel (400 mm × 200 mm×13 mm × 8 mm) and C50 concrete (350 mm × 600 mm) with a bonding length of 500 mm. A FE model was established based on the bond-slip model to analyze the nonlinear bonding stress that are difficult to obtain from the experiment. The research shows that although the bonding stress in the elastic stage is not uniformly distributed, it is basically uniformly distributed when the ultimate bearing capacity is reached. It proves that assuming the average interfacial bonding stress under ultimate load to replace the maximum bonding stress is reasonable, which is crucial for designer to estimate interface bearing capacity and maximum bonding stress. Moreover, five different stages were obtained by the FE model analysis and the theoretical equations of bonding stress nonlinear distribution were obtained based on the boundary condition of each stage. The theoretical solution clearly showed the relationship between interface nonlinear stress distribution and influencing parameters including the bond area, elasticity modulus of material, section area of specimen, bond-slip constitutive model, and the external load. Based on the theoretical model, the influences of different parameters can be directly obtained without conducting further experiments and establishing different FE models.

Behavior of concrete-filled double steel tube stub columns under partial compression

This paper reports the investigation on the behavior of stub columns having two nested steel tubes filled with concrete, abbreviated as CFDST, consisting of core concrete, inner and outer steel section and sandwich concrete. A total of twenty-seven stub columns were fabricated and tested. The experimental parameters included the wall thickness of the outer steel tube, strength grade of the concrete, ratio of the partial compressive area and the cross-sectional shape of the bearing plate. The typical failure modes, load-displacement relationships, and stress-strain relationships were studied. The results showed that outward bulging of the upper end of the outer steel tube occurred for the CFDST columns, and the degree and extent of bulging increased with the ratio of the partial compressive area. The bearing capacity of the columns loaded on the partial compressive area increased with the wall thickness of the outer steel tube and concrete strength. When the wall thickness of the outer steel tube increased, the partial bearing capacity increased by 25.3% on average. Reduction of the ratio of the partial compressive area improved the compressive bearing capacity. However, the shape of the bearing plate had a minor effect of the bearing capacity. Based on the experimental results, the FEM model was developed for analyzing the bearing capacity of the CFST and CFDST columns. The results of the analyses were found consistent with the experimental results.

A simplified method for thermal buckling verification in steel–concrete composite elements

This paper delivers a comprehensive analysis of the thermomechanical behavior of steel–concrete (SC) composite elements under elevated temperatures, up to 200 °C, as these can be encountered in accidental scenarios within nuclear power plant operations. The focus lies on the thermal buckling of external thin steel plates. We undertake an integrated approach, combining an experimental campaign and numerical simulations, to investigate thermal buckling phenomena. Using these findings, along with principles from thermoelasticity and thin plate theory, we establish an analytical model to guide preliminary SC element design. The efficacy of this model is ascertained through rigorous comparisons with experimental and numerical results. The paper concludes by demonstrating the model’s practical utility for thermal buckling verification through a relevant case study.

Flexural Behavior of High-Strength Steel and Ultra-High-Performance Fiber-Reinforced Concrete Composite Beams

The flexural performance of steel and concrete composite beams can be further enhanced by utilizing advanced construction materials such as ultra-high performance fiber-reinforced concrete (UHPFRC) and high-strength steel. In this paper, the concept of critical elastic moment resistance is proposed and the equation for its estimation is derived. It was found that the high yield strength of steel calls for a narrow UHPFRC top layer to reach the critical state, whereas this ideal condition is not realistic for composite beams with normal-strength steel and UHPFRC. Small-scale composite beams composed of both high-strength and low-strength steel materials were tested under four-point bending to verify the critical state and performance of different types of connectors. The headed studs and plate connectors were first tested through small-scale push-out tests and then implemented in the composite beam with different spacing. The connection utilizing headed studs with 150 mm spacing performed the best among the three tested specimens in helping reach the critical elastic moment resistance. Finite element analyses of the composite beam were performed based on the estimated material properties under axial and biaxial stress conditions and the results align with the experiment results.

Behavior of steel tubed rubberized geopolymer concrete columns under axial compression: Experimental study and analytical modeling

Rubberized geopolymer concrete (RuG) has become increasingly popular due to its capability of sustainable utilization of resources, but the mechanical properties of RuG could deteriorate significantly with the increase of rubber content. To mitigate the adverse effects of rubber and further promote the engineering applications of eco-friendly building materials, a new type of composite column, i.e., steel tubed rubberized geopolymer concrete (ST-RuG) columns, was proposed and tested in this paper. The influence of concrete types, rubber replacement ratios, the configurations of steel tubes, and diameter-to-thickness ratios on the compressive behavior of specimens was analyzed. The test results show that the incorporation of rubber has a deterioration effect on the strength of ST-RuG columns with a maximum degradation of 37.6%, but it can improve the ductility of specimens to a certain extent, which is slightly superior to steel tubed rubberized ordinary concrete (ST-RuO) columns. Due to the inherent brittleness of geopolymer concrete (GPC), more obvious residual behavior is detected for ST-RuG compared with ST-RuO under the same rubber replacement ratio Rf. Moreover, with the increase of Rf, the confining pressure of ST-RuG specimens gradually decreases, and a significant decreasing trend is observed for both the peak stress ratio and residual strength ratio of confined RuG. Finally, a new stress-strain model considering the effect of rubber replacement ratio is developed, and comparisons with test results reveal that the proposed model possesses satisfactory accuracy in predicting the axial stress-strain curves of steel-confined GPC and RuG.

Push-out tests on steel composite sections with engineered cementitious composite

This paper investigates the shear strength and failure modes of steel-concrete-steel (SCS) sandwich composite member with Engineered Cementitious Concrete (ECC) and explores the influences of various shear connectors such as headed stud and bolt on shear behavior of SCS sandwich composite member by carrying out push-out testing program. Based on the test results in this study, the failure modes and the load-slip behavior of the specimens are investigated. In addition, the experimental results on the shear resistance of the headed stud connector with various connector spacing and numbers of connector is compared and explored.

Comparative Investigation of the Tensile Strength of Steel Bars With and Without Couplers

Connection in reinforced concrete is unavoidable due to limited length of steel. As known the maximum length of steel 12 metres and used for beams, columns, plates, foundations, etc. Sometimes several buildings use long spans between column to column for architecture causes longer steel needs. If spans are more than 12 metres the steels should be connected by welding, coupler drates, and other parts of connection. Coupler drates one of the most popular connection and it is easy to make connection between steels in the reinforcement concrete. This research aims to determine the behaviour of steels when they were tensioned at testing machine either full steel bar and connected steel bar by coupler drates. The testing was conducted at the materials laboratory the references for testing are Indonesian standards for testing materials like SNI - 2052 - 2017, SNI - 8389 - 2017 and SNI - 07 - 0408 - 1989. The type of steel bars for testing are drate steels of diameters 25 mm and 32 mm and the type of test is tensioning test. The results of testing for normal steel bar of D- 25 mm is 619.3 MPa and D-32 mm is 636 MPa respectively and steel bar with coupler drates for D- 25 mm is 428 MPa and D-32 mm is 522.5 MPa respectively. It means tension strength of D-25 mm coupler drates decreases 30.88 % and tension strength of D-32 mm decreases 17.84 % as compared with steel bars.

A Review of Research on the Bond-Slip Behavior of Concrete-Filled Steel Tubes with Varying Confinement Interface Damage

The structural safety of concrete-filled steel tubes primarily depends on the interfacial bonding between the steel tube and concrete, two heterogeneous materials. Simultaneously, varying confinement interfaces have diverse impacts on the bond-slip behavior of concrete-filled steel tubes, leading to a variety of damage and failure modes. This article reviews research on the performance of concrete-filled steel tubes, explores damage at different confinement interfaces, and collates findings on bond-slip behavior under various confinement interface conditions, aiming to provide a reference for subsequent studies.

Experimental Investigation on Beam with Composite Reinforcement Using Mild Steel Tube In-Filled with Crumb Rubber

In today developing consequence, innovative alternates are being familiarized from recycled wastages used in concrete construction. This study concentrates on alternate reinforcement in the structural elements. The conventional reinforcement is replaced by the rubber composite reinforcement using in-filled tubes. The bond relation among the mild steel tube and concrete is simply good. The performance of the composite reinforcement using rubber in-filled tubes are comparing to the conventional reinforcement. The composite reinforcement is made by in-filling the mild steel tubes with cement slurry and crumb rubber. And the crumb rubber gained from the cracker mill. This crumb rubber institutes to the solid waste management. The scrap tires are prepared into crumb rubber and mixed with water – cement in a mortar ratio of 1:1:2 (water: cement: sand) to attain the colloidal consistency. 40% of 177-micron size crumb rubber sieves replaced instead of sand. This crumb rubber constitutes to the solid waste management and light weight. Hence these composite reinforcements will reduce weight of steel in reinforced concrete along with the decrease in cost of construction. This idea inspects the flexural strength of concrete beam with composite reinforcement, Mild steel pipe reinforcement and ordinary reinforcement by third point loading.

无上弦空腹钢桁架–混凝土板组合楼盖弯剪承载力相关性研究

无上弦空腹钢桁架–混凝土板组合楼盖弯剪承载力相关性研究

Thermal Response Characteristics of Concrete-Filled Steel Tube Columns with Flame Encapsulation Thickness

In order to elucidate the influence of flame encapsulation thickness on the thermal response characteristics of concrete-filled steel tube columns in a fire environment, a study was conducted focusing on the primary control mechanism of heat radiation power from fire——the thickness of fire encapsulation. The thermal resistance effect at the interface between the steel tube and concrete, as well as the temperature rise characteristics of the flame, were comprehensively considered. A calculation method was established for the thermal response characteristics of concrete-filled steel tube columns under different flame encapsulation thickness conditions, providing support for the simulation of thermal response and temperature rise prediction of concrete-filled steel tube columns in fires. The results indicate that the flame emissivity and radiant heat power increase with the increase of flame encapsulation thickness. As the flame encapsulation thickness gradually increases, the growth trend of flame radiant power slows down. When the flame encapsulation thickness L < 1 m, the temperature rise rate of the concrete-filled steel tube column is significant. When the flame encapsulation thickness L ≥ 1 m, the temperature rise rate of the concrete-filled steel tube column tends towards a constant value.

Estudo comparativo de soluções para vigas mistas empregas em obras de arte especiais ferroviárias

Abstract Steel-concrete composite bridges are a popular solution due to the structural benefits of both steel and concrete. The typical system of a concrete slab and steel I-girders for small and medium-span bridges often displays the most economical results. However, other solutions emerge as innovative alternatives for bridge construction, such as composite beams with composite dowels and pre-cambered composite beams. This paper aims to develop a comparative study of these composite beam solutions to delimitate their efficiency, performance, and economy. Thus, a case study for the superstructure of a two-way simply supported railway bridge is detailed to define the composite beam’s performance indicators. The innovative alternatives presented benefits when compared to the traditional system, demonstrating the positive impact of their use on bridges.

In-Plane Shear Transfer between Thin Concrete Slabs with Concrete Shear Keys and Steel Shear Plate

In-Plane Shear Transfer between Thin Concrete Slabs with Concrete Shear Keys and Steel Shear Plate

ELASTIC-PLASTIC DEFORMATION OF STEEL-CONCRETE BEAMS WITH LOCAL CRUMPLING DURING THREE-POINT BENDING

The study presents the results of experimental modeling of elastoplastic deformation of bent massive concrete filled steel tube beams under three-point bending. It has been shown that local deformations and local crushing in such structures have a significant impact on their behavior. The applicability of the theory of bending of a hollow steel beam according to the Bernoulli model is analyzed. A comparison has been made of the bearing capacity and stress-strain state of hollow steel tubes (according to the Bernoulli model and the results of experiments) and concrete filled steel tube beams, and the contribution of the concrete core to the bending resistance during elastoplastic deformation has been quantitatively assessed. The actual load-bearing capacity of a hollow pipe during three-point bending does not exceed 50% of the calculated theoretically determined one, which indicates the impossibility of using the classical bending model when designing systems of this kind. In this case, the concrete filled steel tube beam not only ensures the full functioning of the metal during the deformation process, preventing its disruption, but also provides some increase in load-bearing capacity due to the inclusion of a compressed zone in the concrete work. The increase in the load-bearing capacity of a beam due to the introduction of a concrete core can reach 70%. Despite their significant weight, bendable tube-concrete rods can be recommended in conditions of a complex stress-strain state, in which, in addition to transverse bending loads, significant longitudinal forces arise, as well as local force factors that contribute to the occurrence of local crushing deformations, since, unlike a thin-walled hollow tube, concrete the core significantly prevents these effects. Based on the results of the study, the potential effectiveness of flexible tube-concrete elements for a number of structures was proven.

Identification of Damage in Steel‒Concrete Composite Beams Based on Wavelet Analysis and Deep Learning

Identification of Damage in Steel‒Concrete Composite Beams Based on Wavelet Analysis and Deep Learning

Fatigue Performance of a Novel Steel–Concrete Joint of a Long-Span High-Speed Railway Hybrid Girder–Cable-Stayed Bridge

Fatigue Performance of a Novel Steel–Concrete Joint of a Long-Span High-Speed Railway Hybrid Girder–Cable-Stayed Bridge

Axial compressive behavior of recycled aggregate concrete steel composite columns

In this Study the axial load-carrying capacity and behavior of a “Axial Compressive behavior of Recycled Aggregate Concrete Steel Composite Columns” (RACSCC) is investigated experimentally and simulated numerically. The study emphasizes the utilization of materials contributing to the circular economy in construction, specifically integrating steel and recycled aggregate into concrete. The environmentally sustainable concrete columns are formed by filling square steel tube sections with recycled aggregate concrete (RAC). The study includes six SRACC specimens and one bare conventional steel column. The specimens are subjected to axial compressive loading using the displacement control method. The investigation explores the impact of different coarse aggregate sizes of 12 mm, 16 mm, 22.4 mm, 25 mm, and 30 mm, obtained through sieving of demolished buildings materials. The study aims to address the impact of varying aggregate sizes on parameters such as maximum load-carrying capacity, strain, stress, lateral displacement, and failure patterns. The experimental results are validated and compared with the maximum load-carrying capacity, Strain, Stress, Lateral displacement, and failure patterns using numerical simulations conducted with the Ansys Workbench tool. The SRACC column comprises a hollow tube with 20 mm to 22.4 mm and 22.4 mm to 25 mm recycled aggregate and has a maximum load carrying capacity of 610.28 kN at 10 mm displacement. The local buckling failure occurred near the area load applied. The numerical simulations result for the composite columns agreed well with the experimental results. The results show the recycled aggregate concrete (RAC) have a massive potential for construction support in circular economy. To create composite columns using the RAC as an alternative building material that will help to create an environmentally Sustainable construction

Optimal Design of a Novel Large-Span Cable-Supported Steel–Concrete Composite Floor System

This paper optimizes the design of a novel large-span cable-supported steel–concrete composite floor system in a simply supported single-span, single-strut configuration, aiming for cost-effective solutions and minimal steel consumption. The optimization considers various cross-sectional dimensions, adhering to building standards and engineering practices, and is based on a non-linear programming (NLP) algorithm. Parameters of live loads ranging from 2 to 10 kN/m2 and spans from 20 to 100 m are considered. The optimization results show that cable-supported composite floors with a single strut exhibit robust economic feasibility for spans of less than 80 m and live loads under 8 kN/m2. Compared to conventional composite floors with welded I-beams, the cable-supported system offers more cost-effective cross-sections and reduces steel consumption. The savings in economically equivalent steel consumption range from 20% to 60%. Discussion on the area ratio of cables to steel beam in the optimal cross-section reveals that the secondary load-bearing system (i.e., bending of the main beam with an effective span length of L/2) may require more steel in cases of ultra-large spans. Therefore, the economical efficiency of cable-supported composite beams with multiple struts and smaller effective span lengths warrants further exploration in future studies.