Steel-concrete Composite Frames Research Articles

Experimental Study of Novel Demountable Shear Connectors for Steel-concrete Composite Buildings

Sustainable composite structures in building construction are assembled using demountable structural elements that can be reused in the circular economy. The current research and development project, in cooperation with Budapest University of Technology and Economics and KÉSZ Group, bim.GROUP Ltd., Hungary, aims to design a novel demountable steel-concrete composite slab and frame system for buildings. The key component of this construction is the demountable shear connector. In the current research, novel bolted shear connectors with embedded bolts and threaded rods are developed and studied that can fit the applied technology of the industrial partner. One of the leading aspects of this connection is the consideration of bolt hole clearance, since it occurs initial slip and stiffness reduction of the composite beam. In the first phase of the research program, demountable and economical structural details were developed, which can reduce the stiffness reduction with the proper resistance and ductility features. To study the behavior of these shear connections, a push-out experimental program was designed and completed in March and April 2023. It is observed that novel shear connectors have a proper behavior with sufficient resistance and ductility, which is applicable according to the Eurocode 4 standard and fits the objectives of the research and development project. In the paper, the developed structural details and the push-out experimental program are presented with general results and statements besides a detailed evaluation of a specified specimen type.

Comparative Seismic Analysis of RCC, Steel & Steel-Concrete Composite Frame

The aim of the present study is to compare performance of a 3D (G+7) story RCC, Steel and composite building frame situated in earthquake zone V. All frames are designed for same gravity loadings. The RCC slab is used in all three cases. Beam and column sections are made of either RCC, Steel or Steel-concrete composite sections. Equivalent static method and Response Spectrum method are used for seismic analysis. SAP 2000 software is used and results are compared. Cost effectiveness based on quantity of materials of all types are determined.

Experimental and numerical study on seismic performance of L-shaped multi-cellular CFST frames

Steel-concrete composite frames have been widely used in high-rise buildings. To improve the utilization efficiency of the indoor area, irregular-shaped concrete-filled steel tubular (CFST) columns were proposed for an alternative of the traditional rectangular CFST columns. In this paper, the L-shaped multi-cellular CFST (LM-CFST) frame was proposed, consisting of LM-CFST columns and H-shaped steel beams. Firstly, four LM-CFST frames were tested under combined axial compression and cyclic lateral loads. The local buckling was observed at both the top and bottom ends of the column, and fracture of steel occurred when the drift ratio was large. The hysteresis curves were spindle-shaped with the ductility indexes of 2.61–3.24. Then, a refined finite element model was established and validated against the test results. A parametric analysis was conducted to study the effect of axial compression ratio, web cell length, concrete strength and steel tube thickness on the seismic performance of LM-CFST frames. It was found that the axial compression ratio could affect the seismic performance of LM-CFST frames significantly, while the concrete strength had little effect. Finally, the compression-bending capacities obtained from the sectional analysis method specified in EC4 were compared with those obtained from tests. It was found that this method could predict the compression-bending capacity of the LM-CFST frame under combined axial compression and cyclic lateral loads with reasonable discrepancies.

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.

Experimental and analytical study on steel-concrete-ECC composite frames with URSP-S connectors

To improve the slab crack resistance in the hogging moment region of steel-concrete composite frames, this paper proposes using Engineered Cementitious Composite (ECC) and Uplift-Restricted and Slip-Permitted Screw-type (URSP-S) connectors near the columns of the frames, the structural behavior of the innovative steel-concrete-ECC composite frames were experimentally and numerically investigated. Firstly, five 1/2-scaled steel-concrete composite frames were experimentally studied under vertical uniform slab loading and horizontal low cyclic loading. The failure mode and cracking, load-displacement relationship, stiffness and strength degradation, energy dissipating, and strain of composite frames with ECC and URSP-S connectors were analyzed, and good cooperative behavior and overall seismic performance were found. Then, it was compared with the results of the other four specimens with different slab materials and shear connector types. The experimental results showed that the use of ECC and URSP-S connectors improved slab crack resistance 55% in terms of crack width, and rarely influenced the structural performance of the composite frames. ECC played a major role in controlling the crack width while URSP-S connector played a major role in controlling the crack number. In addition, based on the test specimen with ECC and URSP-S connectors, an elaborate finite element (FE) model was developed and validated by the test results in terms of cyclic curves and failure mode. Moreover, supplementary modeling analyses with various parameters on the influence of the frame capacity were performed, where steel beam height was the most influential parameter.

The structural design and earthquake resistance assessment of composite steel–concrete frame structures with welded dissipative fuses

Mitigation of earthquake damage to buildings is a major task in structural engineering. A reliable reinforced concrete structure with composite joints is crucial to create a high-performance structural system. The paper develops and investigates alternative dissipative systems with welded fuses in reinforced concrete structures, particularly, composite steel–concrete frame structures. This paper discusses the findings of an experiment on the mechanical properties of three types of plate flanges with different geometric parameters and power factors under different cyclic loadings. Sample ductility, dissipation, and durability made it clear that increasing the plate’s cross-sectional area leads to increased bending stiffness coefficient and reduced intensity of stiffness degradation during cyclic loading. The tensile strength is twice the yield in the case of sagging, while these values are very close in the case of hogging. Samples with a high power factor have low dissipative properties, thereby contributing to the rapid wear of non-replaceable parts. Plates with a 10 × 100 mm2 cross-section have a sufficiently high resistance and the ability to dissipate the seismic vibration energy. The findings can be used in the design of residential and industrial buildings with reinforced concrete structures with welded fuses. Further research involves studying the effect of other plate parameters on improving the composite structure’s plastic parameters.

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.

Spiral-based confinement in slabs for the seismic performance enhancement of steel-concrete composite frames

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 – Annex C for the optimal detailing of transversal 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 improve 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 is explored for several spiral-confined slabs, based on various arrangements. Major advantage is take from literature experimental data on RC slabs, that are further investigated by introducing the examined confinement technique. 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 steelcomposite frames as a whole.

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.

Experimental study on cyclic performance of steel-hollow core partially encased composite spliced frame beam

Novel frame beams differ from the traditional steel-concrete composite frame beam, named as steel-hollow partially encased composite spliced frame beam (SHSFB) and steel-partially encased composite spliced frame beam (SPSFB) is proposed herein. SHSFB and SPSFB are “false steel-concrete composite structures”, actually, they are regarded as steel structure in mechanism analysis. Plastic hinge is located on the stub beam, while the mid-span of the beam is a steel-concrete composite beam. Their deformation and bearing capacity are similar to that of the steel structures. The novel frame beams also have the advantages of easy construction, steel saving, and good lateral stiffness. In order to study the seismic performance of the novel structures, five specimens were tested under cyclic loading. All specimens showed excellent seismic capacity. When the stub beam was long, its hysteretic curve was more similar to that of the steel frame beam; when the stub beam was short, the ductility, energy dissipation capacity, and drift ratio of the specimen were better, especially for SHSFB. In addition, the flexural capacity of the novel frame beam was calculated. According to the test results and analysis, the thickness of independent beam flange, filling amount of concrete, and length of stub beam are optimized.

Experimental and numerical study on steel-concrete composite frames with engineered cementitious composites

Engineered cementitious composites (ECC) is a type of cement-based material with the characteristics of tensile strain-hardening and multiple cracking. In this study, the structural behavior of the composite frame, whose crack resistance is improved by using ECC in the hogging moment region, was investigated. A large-scale steel-concrete composite frame with ECC at the beam end was designed and tested under vertical and lateral hysteretic loads. The test results were reported and compared with those of the traditional steel-concrete composite frame conducted by the authors in a previous study. The application of ECC notably reduced the crack width by 18%-40% in terms of the results under vertical loading cases and enhanced the ductility by 87% in the positive loading direction. The steel-concrete-ECC composite frame exhibited excellent seismic behavior with similar strength, stiffness, energy dissipation, stiffness degradation and strength degradation as the traditional steel-concrete composite frame. In addition, a nonlinear elaborate finite element (FE) model was established to simulate the tested frames, whose results agreed well with the test results. Furthermore, parametric studies on the ECC composite frames were performed via FE simulations, from which the influence of the ECC length, ECC tensile strength, ECC compressive strength and the steel beam height on the bearing capacity and cracking performance were clarified. The design method of the ECC length was also suggested. The test and FE results showed that ECC notably improved the slab anti-cracking performance. The study of this paper will provide a scientific basis for the application of ECC in steel-concrete composite frames to some extent.

System reliability-based design of steel-concrete composite frames with CFST columns and composite beams

This paper presents an effective reliability analysis procedure and proposes the system resistance factors for the system design of steel-concrete composite frames that comprise of concrete-filled steel tubular (CFST) columns and composite beams. Advanced analysis is employed to predict the ultimate resistance of frames using fibre beam-column elements in OpenSees. The obtained predictions of the load-carrying capacity of frames compare well with experimental results with the mean value of the test-to-prediction ratio around 1.027 and the coefficient of variation (CoV) of 8.4%. Both Monte Carlo (MC) and subset simulations are used in the reliability analysis. The uncertainties of model error, geometric and material properties, and external loads are included to predict the system reliability index. Five different frame configurations are considered. The results of the reliability analysis show that the system resistance factors for both US and AS codes are quite similar. In the case of gravity load, the system resistance factor is from 0.78 to 0.90, whilst this value for the case of combined wind and gravity load is from 0.8 to 0.95. The resistance factors suggested herein become valuable reference information for the system design of composite frames.

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.

Analysis and cost comparison of framed structure using different building materials under different load combinations

In the present study, the analysis and cost comparison of framed structures using different building materials under different load combinations were carried out. G + 7 storey framed structure of 24 m high was analysed for 8 load cases and 4 different load combinations. The bay width was maintained as 4 m in both directions (16 m × 16 m) and analysis was achieved through the licensed version of STAAD.Pro CONNECT V22. The material properties assigned were concrete, steel, and steel-concrete composite. The total cost of material utilised was calculated, with reference to the unit costs mentioned in the Standard schedule of rates. The cost comparison was carried out for each type of material under different load cases and different load combinations. It was observed that under extreme load combination, the concrete frame showed the increase in cost of 77%. Whereas the corresponding increase in steel-concrete composite frame and steel frame were 62% and 50% respectively. Even though the initial cost of steel structures is high, these structures were found to be optimal with less increment in cost under extreme load combinations.

A Review on Multi-Storey RCC& Composite Building Under Seismic Effect using E-Tabs Software

The Steel-concrete composite constructions are commonly used in modern construction. Due to its several advantages over RCC and steel structures, composite structures consisting of steel and concrete are particularly popular. The structural members of RCC buildings are heavier and have larger cross-sections. Steel constructions have higher deflections and flexibility than concrete structures, helping resistance to earthquake loads. In composite structures, the appropriate qualities of RCC and steel structures are blended. The composite structures facilitate lower costs, quick construction, and fire protection, among other attributes. Present study covers comparison of high-rise (G+8) RCC and composite structures in seismic zone IV considering the provisions of IS: 1893 (Part1) -2002. The seismic behaviour of frames created using the suggested methodology is assessed using ETABS software's nonlinear time-history analysis and the results are compared using various parametric data, for structures in all sorts of building frames, maximum storey displacement, storey stiffness, storey drift, fundamental time periods, base shear, and weight are determined. The steel-concrete composite frames, along with RCC and steel constructions, are best suited for medium to high rise buildings, according to comparative research.

Comparative Study Seismic Analysis of RCC, Steel & Steel-Concrete Composite Frame: A Review

Abstract: This study examines how composite structures are gaining popularity in developing countries. For medium and high levels in RCC buildings are no longer economical due to increased weight, range limitations and low natural frequencies and dangerous formwork. Steel and concrete composite structures are becoming increasingly popular today and are safe throughout their useful lives. Round Steel and concrete structures are the best solution for modern buildings. In this article we will discuss the various results of building construction for RCC, metal and composite construction taking into account different studies. Keyword: RCC Structure, Steel Structure, Composite Structure, Joint Displacement, Base Shear

SEISMIC ANALYSIS OF STEEL-CONCRETE COMPOSITE FRAME STRUCTURES BASED ON THE ULTIMATE BALANCE THEORY

A simplified analysis method of steel-concrete composite frame structures under rare earthquake action is established based on the ultimate balance theory. The failure mechanism of composite frames is determined by theoretical analysis and experimental phenomena. Based on the ultimate balance theory and according to the distribution law of the deformation and internal force when the structure reaches the ultimate strength under earthquake action, the seismic strength of the composite frames is calculated when the top horizontal displacement of the frame is equal to H/50, H/40 and the lateral displacement corresponding to the limit load. The calculation results agree well with the low cyclic loading test results of 19 composite frames at home and abroad. It shows that the method can effectively predict the seismic strength of composite frame structures under rare earthquakes. A simplified method is proposed to control the deformation capacity and seismic strength of the composite frame at the same time to make the structure meet the seismic requirement under rare earthquakes.