Concrete Composite Frame Research Articles

Column-to-beam flexural strength ratio for rigorous strong-column–weak-beam design for steel–concrete composite frames

This study addresses the limited research and unclear principles surrounding the strong-column–weak-beam (S-C–W-B) criterion in steel–concrete composite frames, a critical aspect of structural engineering. Despite its widespread application in steel frames, the S-C–W-B criterion's adaptation to steel-concrete composite frames remains underexplored. The research aims to clarify and establish consistent guidelines for preventing column hinge formation at the joint, a key concern in S-C–W-B design. Beginning by analysing the definitions of ultimate flexural strength and flexural yielding strength of a section, essential components of the S-C–W-B criterion, the minimum column-to-beam flexural strength ratio (ηc, min) required for a robust S-C–W-B design was deduced. The methodology involves a novel parametric analysis using a fibre beam–column model. This model is used to derive a closed-form equation for ηc, min, which was then verified through time-history analysis using the finite-element software MSC.Marc. The findings indicate that the established ηc, min provides a stringent, nonetheless, reliable criterion for S-C–W-B design in steel-concrete composite frames. This research not only bridges a significant gap in existing structural engineering knowledge but also proposes a practical approach for safer and more efficient design in real-world applications.

Seismic Behavior of Steel Reinforced Ultra-High Strength Concrete Composite Frame: Experimental and Numerical Study

The seismic behavior of steel reinforced ultra-high strength concrete (SRUHSC) composite frame was investigated through finite element analysis (FEA) modeling. A FEA model for the seismic analysis of the SRUHSC frame was first established and verified with test results. The numerical model was subsequently used to study the seismic performance of the SRUHSC frame, including the P-Δ skeleton curves, the stiffness degradation, the failure mode, the subsequence mechanisms of plastic hinges and the stress–strain distribution. Finally, a parametric study was carried out to investigate the effect of salient parameters on the behavior of the SRUHSC frame. It was found that with the increment of the concrete strength, yield strength of steel, and linear stiffness ratio of beam to column, the horizontal load-bearing capacity and the elastic stiffness of the structure were improved, but there was no significant effect on the ductility. With the increment of the volume stirrup ratio and structural steel ratio, the horizontal load-bearing capacity and the ductility of the structure were both improved. However, with the increment of the axial-load ratio, there was no obvious change in the elastic stiffness of the structure, but the horizontal load bearing capacity and the ductility of the structure decreased obviously. In addition, the accuracy of a concrete constitutive model in the different degrees of constraint for the SRUHSC frame proposed by the authors was verified with the FEA model.

Bearing capacity and stability of reinforced concrete composite frame without collar beams at different operating stages

The paper studies the load-bearing capacity and stability of reinforced concrete composite frame without collar beams during linear and physically nonlinear operation of its materials under static loading.Purpose: The strength analysis of a reinforced concrete frame without collar beams using the coefficient of structural strength in the linear calculation and use factor by bearing capacity determined by the limit surface of elements, as well as linear and physically nonlinear stability based on the limit repulsion of the system.Methodology: The computational substantiation of the bearing capacity and stability of the reinforced concrete frame at different stages of materials performance, is carried out in the Ing+2021 MicroFe program with the proposed finite element spatial model.Research findings: The structural strength and bearing capacity are calculated for reinforced concrete composite frame without collar beams during linear and physically nonlinear operation of its materials under static loading.

Seismic behaviour of post-earthquake composite frame structures with different damage levels

Since earthquakes pose a huge threat to buildings, the post-earthquake safety assessment is quite important, especially in earthquake-prone areas. This paper investigates the seismic performance of post-earthquake composite frame structures with different damage levels. Two-stage nonlinear time history analysis is carried out for a ten-story steel–concrete composite frame and the peak ground acceleration (PGA) of the seismic waves is used as the main parameter characterizing the seismic intensity and damage level. In the first stage, the seismic waves with the PGAs of 0.20 g, 0.30 g and 0.40 g are applied to the frame to result in three different damage levels. The peak inter-story drift ratios, residual inter-story drift ratios and plastic hinge ratios of the structure in the first-stage earthquakes are analysed, which presents a uniform distribution pattern for the three damage levels. The composite frame is evaluated as structurally safe at all three damage levels based on the limits of residual inter-story drift ratios given in current standards. In the second stage, the seismic waves with the PGA of 0.40 g are used to explore the residual capacity of the structure subjected to strong earthquakes. The dynamic responses of the intact structure and the structure with different damage levels are compared. The results indicate that despite the recognised structural safety, pre-existing seismic damage can enlarge the lateral deformation, reduce the internal forces and resistance capacity and increase the plastic hinges when the composite frame is exposed to the second-stage earthquakes. Generally, the damage caused by earthquakes with the PGA of 0.40 g will have an obvious influence on the seismic behaviour of the post-earthquake structure, in which situation further safety assessment and structural repairs are necessary.

Numerical Study on the Seismic Behavior of Steel–Concrete Composite Frame with Uplift-Restricted and Slip-Permitted (URSP) Connectors

Uplift-restricted and slip-permitted (URSP) connectors have been demonstrated to effectively enhance the anti-cracking performance of RC slabs in negative moment areas. While their efficacy is recognized, studies of composite frames utilizing URSP connectors remain scarce, limiting their application in construction. This research undertakes a numerical analysis of the seismic performance of steel–concrete composite frames that employ URSP connectors. The influence of key design parameters on seismic behavior is scrutinized. Leveraging prior tests on composite frames with URSP connectors carried out by the authors’ group, a sophisticated three-dimensional FEM model is crafted. This model, built using the ABAQUS software (2016), accounts for the intricate mechanical behaviors of shear connectors. The fidelity of the FEM model is validated through a juxtaposition of numerical and test outcomes, assessing strain distribution, damage patterns, and load–displacement curves. This numerical model serves as a basis for the study, exploring the impacts of three crucial design parameters on structural seismic performance. The findings suggest that the arrangement length of URSP connectors should be constrained to less than half of the frame beam’s span to optimize mechanical performance during seismic events. Additionally, enhancing both the flange thickness and the steel beam’s height is recommended to further bolster structural integrity.

Seismic Behaviors of Novel Steel-Reinforced Concrete Composite Frames Prestressed with Bonding Tendons

To investigate the seismic behaviors of novel steel-reinforced concrete composite frames prestressed with bonding tendons (PSRCFs), 15 groups of PSRCF specimens were designed with the following main parameters: the cubic compressive strength of high-strength concrete (fcu), the axial compression ratio of frame columns (n), the slenderness ratio of frame columns (β), the steel ratio of angle steel (α), the span–height ratio of frame beams (L/hb), and the prestressing degree (λ). Based on the modified concrete constitutive model proposed by Mander and the prestressing effect applied by the cooling method, the finite element models of PSRCFs were established by using ABAQUS software, the static analysis on the frame structures under the combined actions of axial forces and horizontal loads was carried out, and the monotonic load–displacement curves were explored. By comparing with the skeleton curves obtained by the experimental hysteretic curves, the rationality of the modeling method was verified. The PSRCFs had good mechanisms of strong columns and weak beams. Based on this, the influences of different parameters on the seismic behaviors such as hysteretic curves, skeleton curves, stiffness degradations, energy dissipation capacities, and ductility of the specimens were investigated. The results show that the hysteretic curves of the PSRCFs are full and have no pinch phenomenon. The ultimate load and the stiffness degradation of specimens can be improved significantly by increasing α, and on the contrary, the ultimate load and stiffness degradation decreased by increasing β. The ductility of the specimens decreased gradually with the increasing β and n. The energy dissipation capacity of the specimens decreased with the increasing β. The trilinear model of the skeleton curves and the restoring force model of PSRCFS were established by statistical regression, which agree well with the numerically simulated results. These can provide theoretical support for the elastoplastic analysis on this kind of PSRCF structure.

Experimental assessment of an asymmetric steel–concrete frame under a column loss scenario

Several noteworthy accidents clearly pointed out the risk of disproportioned collapse of framed structures. Design codes recently recognized it by adding a new requirement: the structural robustness. Among the different approaches to check robustness, the most popular is associated with the column loss scenario: the analysis should verify that, in case of a column loss, an alternative load path does exist, limiting the portion of structure affected by collapse. Consequently, numerous experimental and numerical studies of 2D and 3D structures were carried out in recent years to identify the mechanism of load transfer from the damaged to the undamaged part of the structure. This knowledge becomes an essential and fundamental key for assuring adequate resistance against progressive collapse by the development of catenary action in the beams and membrane action in the floor slab. Studies of reinforced concrete systems and of bare steel sub-assemblies are numerous. More recent is the focus on the response of steel–concrete composite structures subjected to accidental events. Furthermore, most of these studies focused on the characterization of 2D sub-assemblies or 3D in-scale framed structures. This paper presents an experimental assessment of the structural response of a 3D full-scale steel and concrete composite frame under the column loss scenario. The results are finally compared with the response of a frame with the same overall geometry but different columns’ layout, tested by the Authors within the same research programme.

Experimental study on the seismic performance of a cold-formed thin-walled steel–concrete composite column-H steel beam frame

For lightweight steel frame structures consisting of steel H-beams and cold-formed steel columns filled with concrete, seismic performance comparison tests and numerical simulation analyses were performed for bare and infilled frames. The effects of the lightweight wall panels, the axial compression ratio and the wall thickness of the steel sections of the columns on the seismic properties of the structure were investigated. The failure of the bare frame was concentrated in the weld fractures at the beam-column joints. When the wall panels were embedded in the frame, the damage was concentrated at the corners and edges of the wall panels and the connectors. The wall panels significantly improved the initial stiffness of the frame, early energy dissipation and resistance, and the wall panel energy dissipation rate was initially as great as 91%. As the axial compression ratio increased, the resistance of the structure significantly decreased. Under monotonic loading, the resistance on the structure with an axial compression ratio of 0.4 was reduced by nearly 44% compared to the structure without axial compression. Increasing the wall thickness of the steel sections of the columns increased the load-bearing capacity of the structure, but the increase diminished with increasing wall thickness.

Experimental study on in-plane behavior of composite frame slabs and the influence of out-of-plane effect

This paper experimentally investigated the in-plane behavior of a steel–concrete composite frame slab under cyclic loading by considering the influence of the out-of-plane effect. A pure in-plane loading test and two in-plane loading tests of frame slabs with different out-of-plane loads were designed and conducted. Subsequently, the test observations, load–displacement relationships, and shear and flexural deformation components were discussed to investigate the in-plane load resistance behaviors and failure mechanisms of the composite frame slabs with different out-of-plane loads. The experimental results of the pure in-plane loading test demonstrated an evident shear cracking concentration behavior and a pinching hysteretic curve associated with a typical shear-tension failure mode of the composite frame slab. Further, the in-plane loading test of the composite frame slab with small out-of-plane loads also exhibited a typical shear-tension failure mode, and thus had a load–displacement relationship similar to that of the pure in-plane loading test. In contrast, the in-plane loading test with large out-of-plane loads exhibited a horizontal shear failure mode, and thus exhibited a load–displacement curve with a more obvious pinching effect and significantly decreased ultimate load capacity. In addition, the influence of the out-of-plane loads on the in-plane stiffness of the composite frame slab was analyzed.

Numerical investigation of collapse behavior of steel–concrete composite frames containing corrugated webs with and without openings

As an alternative to flat webs (FWs), corrugated webs (CWs) in composite beams have been employed extensively in steel construction systems. However, the collapse behavior of steel–concrete composite frames containing CW beams has not yet been studied and requires urgent investigation. In this study, numerical models were developed to explore the collapse behavior of these composite frames in an internal column removal scenario. Subsequently, the verified modeling methods were used to conduct a comparative study on the collapse resistance performance of models containing FW and CW beams with and without openings to explore the evolution of their collapse behavior. The results reveal that the load-resisting mechanisms of the composite frames containing FW and CW beams are substantially different. The total resistance of the composite frames containing FW beams is a result of both flexural and catenary action, whereas that of the frames containing CW beams is mainly a result of flexural action only. Appropriate openings on the beam web can intensify the catenary action. Furthermore, an extensive numerical parametric study of the composite frames containing CW beams was conducted to elucidate the effect of key parameters, such as the corrugate shape, type, and angle, on the collapse behavior. The effects of the opening type, diameter, end distance, and spacing on the collapse behavior of these frames is also investigated. Finally, three strategies for improving the bearing capacity of the composite frames containing CW beams with openings are proposed: reinforcement by stub tubes, kinked plates, and a skin diaphragm. The results reveal that all these strategies can substantially improve the bearing capacity.

Seismic Response Analysis of Steel–Concrete Composite Frame Structures with URSP Connectors

The uplift-restricted and slip-permitted (URSP) connector is a new type of connector used in steel-concrete composite structures that has been proven to improve the structural performance of negative moment regions. Since this connector changes the interface restraint between the slab and steel beam, there is an imperative to study the seismic performance of steel-concrete composite frame systems with this new type of connector. In this study, the dynamic behavior of composite frame structures with URSP connectors under seismic loads was numerically investigated. First, a beam-shell mixed model was used and complex interfaces of different connectors were considered while establishing a numerical model to conduct elasto-plastic time history analysis under various seismic loads. This numerical model was validated with the frame sub-assemblage experimental results of quasi-static cyclic tests. Second, the model analysis results of structures with URSP connectors were obtained and compared with those of traditional structures. Third, dynamic response results including roof displacement, inter-story displacement, and the distribution and failure modes of plastic hinges were analyzed and compared. The comparisons indicated that the arrangement of full-span URSP connectors had a non-negligible influence on the dynamic behavior of the systems. The arrangement increased the maximum inter-story displacement by 31.5% and induced adverse effects in certain cases, which is not suggested in the application of URSP connectors. The partial arrangement of URSP connectors had little influence on the dynamic behavior of the systems, and the frame systems still showed a good seismic performance, which was the same as the traditional composite structural system. These findings may promote the application of URSP connectors in composite structures.

Configuration Features and Calculation Mechanisms of the Composite RC Column-Steel Beam (RCS) Joints: State of the Art

Reinforced concrete and steel (RCS) composite moment frame structures consist of reinforced concrete (RC) columns and steel (S) beams. Such systems combined with several advantages of the two structural members have larger structural stiffness, lower cost, and faster construction speed than the traditional concrete or steel frame system to be a particularly well viable alternative for use in seismic risk regions. The calculation of joint shear capacity is an essential step in seismic design. This study introduces the typical configuration characteristics of the RCS connection and reviews the state of the art of the shear bearing capacity in terms of failure models, shear distribution mechanisms, calculation mechanisms, and requirements given in the experimental and theoretical study to provide reference and foundation for the subsequent study. Finally, the development of recommendations and further research studies on seismic performance of RCS composite frames are provided.

Progressive collapse analysis of experimental building skeleton based on stress-strain state of columns and joints

Purpose: The aim of this work is to compare three methods of the progressive collapse analysis of the experimental building skeleton based on the stress-strain state of the columns and joints. Design technique: The stress-strain state modeling of the columns is performed for the building with the removed intermediate column in the basement. The building includes a basement and represents a reinforced concrete composite frame without collar beams. The MicroFe software is used for three modeling methods, which include quasi-static, dynamic, and kinematic method of limit equilibrium. The MicroFe analysis is combined with the development of the three-dimensional model on a rigid foundation. Findings: The progressive collapse is proven to be impossible for the building skeleton after the removal of the intermediate column in its basement. Originality/value: Based on the three analytical methods, the limit load reproducibility is 15 %. The dynamic analysis gives higher values of the limit load as compared to the quasi-static and kinematic methods. Practical implications: The proposed procedure of three methods for the progressive collapse analysis can be used for the seismic vulnerability analysis.

Restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall

SummaryTo study the restoring force model of steel‐recycled concrete composite frame with infilled recycled block wall, the experimental results of two recycled concrete‐filled steel tube frames with infilled recycled block walls and three steel‐reinforced recycled concrete frames with infilled recycled block walls under low cyclic loading were analyzed. The four broken‐line skeleton curve model which was suitable for this kind of composite frame was proposed, and the calculation methods for different stages of the skeleton curve were given respectively. According to the hysteretic characteristics of different frame specimens, the hysteretic loops for steel‐recycled concrete composite frame with infilled recycled block wall were simplified by using the treat methods of positive and negative symmetry and sudden drop of bearing capacity, and the restoring force model for different type of steel‐recycled concrete composite frame with infilled recycled block wall was established. At the same time, combing the experimental results, the proposed restoring force model was verified. The results show that the established restoring force model can predict the hysteretic behavior of steel‐recycled concrete composite frame with infilled recycled block wall well, and it can provide theoretical support for the elastic–plastic time history analysis of this kind of frame structures under earthquake.

Improving the seismic capacity of steel–concrete composite frames with spiral-confined slabs

The seismic performance analysis of steel–concrete composite frames involves, as known, the interaction of several load-bearing components that should be properly designed, with multiple geometrical and mechanical parameters to account. Practical recommendations are given by the Eurocode 8 (EC8) – Annex C for the optimal detailing of transverse rebars, so as to ensure the activation of conventional resisting mechanisms. In this paper, the attention is focused on the analysis of effects and benefits due to a novel confinement solution for the reinforced concrete (RC) slab. The intervention is based on the use of diagonal steel spirals, that are expected to enforce the overall compressive response of the RC slab, thanks to the activation of an optimized strut-and-tie resisting mechanism. The final expectation is to first increase the resistance capacity of the slab that can thus transfer higher compressive actions under seismic loads. Further, as shown, the same resisting mechanism can be beneficial for the yielding of steel rebars, depending on the final detailing of components, and thus possibly improve the ductility of the system. To this aim, a refined finite element (FE) numerical analysis is carried out for several configurations of technical interest. The in-plane compressive behaviour and the activation of resisting mechanisms are explored for several spiral-confined slabs, based on various arrangements. Major advantage is taken from literature experimental data on RC slabs that are further investigated by introducing the examined confinement technique. The attention is hence given to the local and the global structural effects due to different arrangements for the proposed steel spirals. As shown, once the spirals are optimally placed into the slab, the strength and ductility parameters of the concrete struts can be efficiently improved, with marked benefits for the overall resisting mechanisms of the slab, and thus for the steel–composite frames as a whole.

Experimental investigation on the behavior of the steel–concrete composite frames with uplift-restricted and slip-permitted screw-type (URSP-S) connectors

The uplift-restricted and slip-permitted screw-type (URSP-S) connector is proved be very useful to improve the crack resistance of the concrete decks in the negative bending moment areas in steel–concrete composite bridges, thus it has been widely used recently in China. However, its application in building structures is very limited. In this paper, the structural behavior of steel–concrete composite frames with URSP-S connectors was experimentally investigated. A total of three composite frame specimens with different connector types and arrangements of the interface of composite beams were designed and tested. The load–deflection curves, hysteresis behavior, slab crack, strain, and interface slip under vertical and lateral cyclic loading cases were analyzed. The results indicated that compared with full-span stud connectors, after applying URSP-S connectors, the crack number and width of the concrete slab was effectively reduced, as well as the tensile strain of the concrete and rebar of the slab, while the interface slip of composite frame beam was notably enhanced, the stiffness of the composite frame with URSP-S connectors became slightly lower under vertical and lateral loading cases. Moreover, the composite frame with URSP-S connectors exhibited good seismic behavior under lateral cyclic loads, and the use of URSP-S connectors rarely affected the bearing capacity of the structures.

Seismic Performance of Steel Concrete Composite Multi-Storey Frame

To investigate seismic behaviour of steel concrete composite multi-storey frame structures, based on researches of composite frame, a concrete encasement rectangular is suggested for the beam and filled steel tube for column. The preliminary demonstrate the excellent performance of the element, and reaffirm the applicability of composite beam-columns to the earthquake-resistant design of multi-storey structures. Then the mode analysis, the response spectrum and time history analysis under rare earthquakes are carried out. Result of ongoing experimental and numerical investigations are shown.

Experimental Analysis of the Behavior of Composite Column-Reinforced Concrete Beam Joints

This study assesses the seismic performance of steel-reinforced concrete (SRC) composite columns connected to reinforced concrete (RC) beam joints, and their ability to dissipate seismic energy through inelastic deformations. In this article, experimental aspects regarding the seismic performance of high-ductility and low-ductility steel–concrete composite frame were investigated. The principle design parameter in this study was ductility, which is considered a conceptual framework in Efficiency-Based Seismic Engineering. Thus, attention was focused on assuring various ductility ranges of joints obtained through a detailed study of the Turkish Earthquake Code (TEC 18) [Ministry of Public Works and Housing.: Turkiye Bina Deprem Yonetmeligi (Turkey’s Earthquake Code for Buildings). Official Gazette (2018) (in Turkish).]. After identifying deficiencies and the energy dissipation capacity in the newly proposed joints, two half-scaled frames with specific ductility-related designs were constructed, instrumented, tested, and analyzed. The specimens were tested under displacement-controlled lateral cyclic loading that incorporated constant axial loading to create cyclic tension and compression facets across the joint areas. The test results proved that the SRC column-RC beam frames employing an extra column reinforcement ratio exhibit slightly better seismic performance. Due to the presence of structural steel, the shear failure of the joint was effectively prevented, even after the formation of the plastic hinge on the interface of the beam. During the testing, the column rebars, to some extent, made a minor contribution to the joint strength of the specimen compared to the structural steel that absorbed almost all of the load applied to the frame.

Finite Element Analysis of Mechanical Performance of Concrete-filled Steel Tube Composite Frame under Different Fire Time

Research on the mechanical properties of concrete-filled steel tube composite frames at high temperatures is one of the current hot issues. In this paper, the finite element simulation software is used to analyze the concrete-filled steel tube composite frame, introduce the failure mode of the concrete-filled steel tube composite frame under high temperature, and deeply study the simulation results of the single-story mechanical performance. The single-span concrete-filled steel tube composite frame structure based on the analysis of the concrete-filled steel tube bearing capacity, including the role of each beam and column in different temperature fields, structural fields and coupling fields, as well as the role in the entire section. As the temperature increases and decreases, its mechanical properties will change significantly under the action of concentrated loads. The bearing capacity of the composite frame at high temperature is somewhat lower than that at room temperature. The research results can provide a reference for the reinforcement and repair of the steel tube concrete composite frame under high temperature.

Mechanical behavior of RC and ECC/RC composite frames under reversed cyclic loading

In this paper, the seismic behaviors of assembled monolithic engineered cementitious composite (ECC)/steel reinforced concrete (RC) composite frame and RC frame were investigated based on both experimental and simulational methods. During the horizontal cyclic loading test, it was found that the ECC/RC composite frame generally kept its integrity while concrete spalling and crushing were observed for RC frame. The energy-dissipating capacity, ductility as well as stiffness for ECC/RC composite frame are higher than those for RC frame. A new finite element (FE) model was also proposed and the accuracy was verified with the experimental results. Based on the proposed FE model, the failure processes of both ECC/RC composite frame and RC frame were analyzed and compared. It was found that the maximum plastic ratio of steel reinforcements for ECC/RC frame is 2.3 times higher than that for RC frame, indicating ECC/RC composite frame has better deformation compatibility between different components. The influences of different parameters on the cyclic behaviors of ECC/RC composite frame, i.e., ECC compressive strength, ECC tensile strain, axial load ratio, and ECC width ratio were also discussed in this paper.