Composite Frame Systems Research Articles

Cyclic performance of precast steel beam-to-CECFST column exterior sub-assemblages with dry connections: Experimental studies and mechanism analyses

Combining advantages of both reinforced concrete (RC) and concrete-filled steel tube (CFST), concrete-encased concrete-filled steel tube (CECFST) members demonstrate superior structural performance over pure RC or CFST counterparts. Nevertheless, current research in this domain has primarily focused on member and connection behaviour of CECFST columns, with no attention given to frame-level performance. This significantly impedes applications of this form of high-performance composite members into actual engineering practice. To bridge this research gap, a novel precast steel beam-to-CECFST column composite system is proposed in this study. This is followed by a comprehensive experimental programme, where seven precast steel beam-to-CECFST column exterior sub-assemblages were tested under cyclic loads. In the test specimens, three types of connections, including beam-to-beam (B-B), column-to-column (C-C) and beam-to-column (B-C), were incorporated to establish a precast steel beam-to-CECFST column sub-assemblage. Horizontal displacement versus shear force relationship and failure mode of the test specimens are reported, followed by a detailed analysis of test results and findings. Furthermore, a comprehensive mechanism analysis is presented, with emphasis on energy dissipation behaviour and deformation mechanism of the proposed precast composite system. The test results show that the proposed precast composite system has comparable load-carrying capacity and energy dissipation capacity in comparison with conventional cast-in-place counterparts. This indicates that despite using precast beam-to-beam and column-to-column connections, structural performance of the composite frame system would not be significantly affected, showing that this form of precast steel beam-to-CECFST column composite system has considerable potential to be adopted in actual engineering practice.

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.

Achieving sustainable built-environment using bamboo composite frame system with cow-dung masonry infills

In today's rapidly urbanizing world, there is dire need for adopting the principles of green/ sustainable built-environment so as to mitigate the ill effects of environmental degradation and climate change. However, demand for housing is on rise in developing countries like India, where sizeable population, especially the low-income strata, still lacks decent quality structurally safe housing. Extensive use of concrete and steel in construction over more than a century has led to detrimental environmental effects such uncontrolled release of greenhouse gases/ pollutants, deforestation and erosion, leading to now visible outcomes of climate change. Bamboo, on other hand provides a sustainable alternative to concrete and steel as a building material since it absorbs the atmospheric carbon dioxide, produces more oxygen than timber producing trees and is a lightweight and renewable building material. Unlike timber, it matures in four to five years and being grass family, is replenishable in nature. However, from structural point of view, the main drawback of bamboo culm is its large slenderness ratio, which renders it weak in resisting bending and compressive loads. This paper presents an alternate structural system utilizing fibre reinforced bamboo composite (FRBC) to overcome the structural deficiency of a single shoot bamboo and build a prototype structure after detailed laboratory evaluation and structural analysis. Structural elements made from FRBC are utilized for fabricating a prototype 3D frame structure, measuring about 24 m2 in plan, representing a modular unit amenable to horizontal and vertical expansion. Eco-friendly materials like cow-dung based bricks and mortar, which offer net zero additional carbon dioxide emissions and circumvent reliance on cement and river sand, have been utilized as masonry infills after structural evaluation. The built structure provides a proof-of-concept demonstration of the feasibility of using bamboo and cow-dung, sustainable building materials, for achieving a structurally safe built-environment. The technology is especially suitable for countries like India which are endowed with tropical climatic conditions. By adopting such environmentally friendly alternatives, the construction industry can create a healthier environment while addressing housing and infrastructure needs in sustainable manner.

ADVANCED ANALYSIS OF STEEL‐CONCRETE COMPOSITE BUILDINGS

AbstractThis paper presents a nonlinear simulation method for composite framing systems constituted from concrete‐filled steel tubular columns (CFST) and composite beam systems. A force‐based fibre beam‐column element in OpenSees was adopted. This element was capable of accurately capturing the local buckling of steel and the confining effect of concrete using the modified stress‐strain relationships of the steel and concrete fibres. A source code for the connection element was also developed in OpenSees to capture the semi‐rigid behaviour of the beam‐to‐column connections of the composite buildings. Through the verification with numerous experiments, the model has shown its capability of accurately simulating composite frames with simplicity and less computational cost. An extensive parametric study was conducted to examine the effect of the bracing systems and the rigidity of the connections on the behaviour and instability of the whole composite buildings.

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.

Steel-concrete composite beam-column connections utilizing prefabricated permanent steel form

To facilitate fast-built and economical constructions, a unique composite moment frame system with prefabricated permanent steel form is presented. A conventional steel wide flange beam is used at the mid-span of horizontal member which has typically small design forces. The so-called composite mechanism between the concrete and steel is utilized selectively on the beam-column connection regions of the moment frame structure, which requires higher strength and ductility demands compared to those in the mid-span. For this purpose, the permanent steel plate forms are prefabricated to the beam-column connection regions before composite with cast-in-place concrete. Since the steel beam is first connected to the steel columns, no additional false work requires during constructions, and high seismic performances can be secured at the beam-column joints, where the structural integrity should be firmly ensured. In this study, full-scale cyclic loading tests were carried out considering the various details at the connection regions as the key experimental variables to evaluate the seismic performances of the proposed composite system. Test results showed that the proposed method fully satisfies the required performances to be accepted as the composite special moment frame specified in the current design code.

High-rise structural stalling and drift effect owe to lateral loading

The challenge is to search out the economic structure system of high-rise buildings within the Indian scenario. This document covers numerous steel systems: moment-stabilizing frame system, composite frame system, luggage rack system with stabilizing belt, structural wall frame system, and frame tube system. Once coming up with multi-storey buildings, truss systems, cluster piping systems for high-rise buildings, lateral hundreds (wind or unstable loads) are principally chargeable for demolition, determining structural systems for high-rise buildings. To form the drift as slight as possible, the beams and columns should be more stiffed. In an exceedingly building with a bit of floor range, the lateral load seldom affects the rise within the building and, therefore, increases size. The part structure considers the aspect load and the doable arranging of the structure. In alternative side load resistance systems beneath study, the force frame’s side displacement is the highest. The lateral displacement of the double frame is the smallest, and the lateral displacement of the slippery wall system is slightly beyond that of the double system.

Experimental Investigation on Double Skin Composite Tubular Column

RCC and steel frames have been the most common frame systems for long times whereas composite frame system has also emerged as popular system for high rise buildings for few decades. Multi-storey composite frames are generally composed of structural steel members made composite with concrete. The use of Double-Skin Tubular columns in building construction has seen renaissance in recent years due to their numerous advantages, apart from its superior structural performance making a typical composite frame structure. Fiber reinforced polymers (FRPs), a relatively new class of non-corrosive, high-strength, lightweight material, have over the past approximately 15 years emerged as practical materials for a number of structural engineering applications. FRP has become one of the most popular methods in the repair and rehabilitation of concrete infrastructure due to its ease of application and the special physical characteristics. This paper focus to determine the compressive strength of columns in different type of specimens under Axial load.

Computational Intelligence on High Rise Structure with Effect of Diverse Load Conditions

The construction of high-rise buildings all overthe world and India is overgrowing. Steel has more advantages in the modern world. Itprovidesan innovativeframe system, easy assembly, a high weight-to-weightratio,differentstrengths, and a more extensive section range. The high-rise structures are environmentally friendly, which iswhy steel is used in high-risebuildingsworldwide. So far, designers have only considered gravity when planning buildings. Earthquakes, wind, and lateral forces havebeen addedto the design. The challenge is to find the economic structure system of high-rise buildings in the Indian scenario. Thisdocument covers various structural steel systems: moment stabilization frame system, composite frame system, roof rack system with stabilizingbelt,shear wall frame system, frame tube system. When designing multi-storey buildings, truss systems, clusterpiping systems for high-rise buildings, lateral loads (wind or seismic loads) are mainly responsible for demolition, which usually determines structural systems for high-rise buildings. Tomake the drift asa minimum, the beams, and columns to beenlarged.In a building with a small number of floors,the lateral load rarely affects the increase in the building and the increase in size. Considering the live and dead loads, the component structureis an option for possible rearrangement of the structure. In other side load resistance systems under study, the side displacement in the torque frame is the highest. The lateral displacement ofthe double frame is the smallest, and the lateral displacement of the sliding wall system is slightly higher than that of the double system.

On the static analysis of laminated composite frames having variable cross section

The complementary functions method (CFM) is used to investigate the static behavior of laminated composite frames consisting of straight and/or curved members of variable cross section. The Timoshenko beam theory (TBT) is used to obtain the set of the governing equations. The fifth-order Runge–Kutta (RK5) algorithm is employed in the solution process of initial value problems via the CFM. A computer program is substantially coded in Fortran on rigidity matrix based on the CFM to acquire the rigidity matrices and load vectors of these structural elements. With the help of the suggested method, the influences of the symmetric layer stacking sequence, the ratio of E1/E2, and various boundary conditions on the nodal displacements and element end forces of the considered frames are investigated. Carrying out the static behavior of laminated composite frame systems which contain straight and circular axis elements for the first time by using the CFM is the novelty of this study. Verification and accuracy of the suggested scheme are intently performed through the comparison of the present results with those of the finite element method. The effectiveness of the method and good agreement of the results are observed.

Seismic behaviour of structural systems with separated gravity and lateral resisting systems

An innovative composite structural system with separated gravity and lateral resisting systems (SGLR system) was proposed to overcome the shortcomings of existing prefabricated structural systems. Two representative frame specimens with a scale ratio of 0.5 were tested under vertical floor loads and lateral cyclic loads to investigate the mechanical behaviour of the SGLR system. The slab crack patterns, failure modes, load–displacement curves, strength and stiffness degradations, energy dissipation capacity, deformation characteristics and strain development were analysed. The experimental results showed that the bent frame specimen (SGLR-1) exhibited good and stable seismic performance and the shear wall–bent frame (SGLR-2) with higher stiffness and capacity demonstrated obvious degradation due to buckling and fracture of steel plates at the bottom of shear walls. From test observations, flexural deformation was the dominated deformation pattern of the SGLR system under lateral loads. On the basis of test data, seismic performance assessment indicated that the SGLR system had larger safety margin than the conventional composite rigid frame (RF) system with the same design criteria of inter-storey drift ratios. The internal force analysis of the SGLR system showed that the base shear distribution in shear walls and columns varied with the increase of overall drift ratio. Moreover, it was revealed from the experimental analysis that the semi-rigidity of connections was significant and had conspicuous influence on both gravity and lateral force transfer mechanisms of the SGLR system.

Hysteresis performance of through bolted connections in CFST frame

This paper presents an experimental study on the seismic performance of composite structural frame systems consisting of concrete-filled steel tubes (CFSTs) and steel beams. The modified, extended end-plate connections were fabricated by straight through bolt for square columns and split bolt for the circular column with a curved endplate. Half-scale CFST composite moment resisting frames were tested under displacement-controlled quasi-static lateral cyclic load. Circular CFST columns possess better confinement than square CFST columns, but the application in construction is restricted due to the difficulty in joining with the steel beams. The present study investigates the strength, stiffness degradation, ductility, failure mode, and energy dissipation characteristics corresponding to the inter-story drift. The results from the tests indicate that the seismic resistance is at par with the American Institute of Steel Construction (AISC) seismic recommendations for composite special moment-resisting frame, and hence the split-bolt assembly can be used as an effective alternate for connection in circular columns. This work also tries to impart the experimental database on the effect of increasing the number of the bay in the resisting direction. Single-bay and double-bay frames were compared to quantify the improvement in seismic performance.

Experimental study on seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads

The steel–concrete composite frame systems are widely used in multistory and high-rise buildings owing to good mechanical performance and high construction efficiency. In previous research on the composite frame systems, many lateral cyclic tests were conducted on specimens with small-width floor slabs without floor loads, which could not precisely reflect the actual behaviour of composite frames in spatial multistory buildings. Therefore, this paper presents an experimental study on the seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads. The specimen was a two-story two-span composite frame with the scale ratio of 0.5, and three load cases, including the vertical floor loading test, the lateral cyclic loading test and the pushover test, were respectively applied to investigate the mechanical performance of the composite frame. The slab crack development, mid-span deflection and strain distribution of slab reinforcements in the vertical floor loading test were discussed. The overall responses of the specimen in the lateral cyclic loading test and pushover test were analysed, including failure phenomena, load–displacement curves, strength and stiffness degradation, energy dissipation capacity and deformation characteristics. Moreover, the seismic performance of columns, beams, slabs and joints in the specimen was discussed in detail and the force mechanism of the composite frame was revealed based on the structural analysis of components. The results indicated that the specimen exhibited sufficient load-bearing capacity, good ductility, stable strength and stiffness degradation and excellent energy dissipation capacity under the combination of vertical floor loads and lateral loads. The welds at the bottom flange near the exterior joint fractured under cyclic loading, which was found to have significant influence on the deformation pattern and force mechanism of the composite frame. The shear lag effect was obvious in the wide floor slabs and the effective width of the slabs was estimated to be nearly 0.75 times the column width.

Comparative Study on Seismic Behaviour of Multi Storeyed Building with Composite and Conventional Columns

RCC and steel frames have been the most common frame systems for long times, whereas the composite frame system has also emerged as a popular system for a few decades. Multi-story composite frames are generally composed of structural steel members made composite with concrete. This study includes a comparison of the seismic performance of a multi-story (G+19) RCC structure with Steel concrete composite structure using ETABS 2016. Here multi-story RCC structure is selected as a study frame and then replaced it by concrete-filled steel tube columns. The structures are assumed to be situated in seismic zone Ⅱ and Ⅳ on stiff soil. The modeling and analysis is carried out using the time history method. Seismic parameters like Displacement, Storey drift, Storey shear, Storey stiffness, Overturning moment, and Base shear are compared. The seismic performance of the CFST columns was found to be better than the conventional RCC structure, and is also found to be economical than conventional RCC structure.

Improvement to composite frame systems for seismic and progressive collapse resistance

Steel-concrete composite frame is one of the widely used structural systems. Earthquake and progressive collapse due to accidental localized damage are the main hazards that affect the safety of steel-concrete composite frames. Therefore, a seismic and progressive collapse resistant composite frame (SPCRCF) structural system is proposed based on a comprehensive consideration of the seismic and progressive collapse design requirements. The seismic and progressive collapse performances of the proposed SPCRCF were compared with the conventional steel-concrete composite frame using the experimental results of four specimens. The general-purpose finite element software, MSC.Marc, was used to simulate the specimens. The experimental and simulation results show that the proposed SPCRCF has better seismic resilience (low damage, self-centering, and easy repair) and larger progressive collapse resistance compared to conventionally designed steel-concrete composite frames.

Shakedown Analysis of Composite Steel-Concrete Frame Systems with Plastic and Brittle Elements Under Seismic Action

Abstract In this paper the earthquake analysis of composite steel-concrete frames is performed by finding solution of the optimization problem of shakedown analysis, which takes into account the nonlinear properties of materials. The constructions are equipped with systems bearing structures of various elastic-plastic and brittle elements absorbing energy of seismic actions. A mathematical model of this problem is presented on the base of limit analysis theory with partial redistribution of self-stressed internal forces. It is assumed that the load varies randomly within the specified limits. These limits are determined by the possible direction and magnitude of seismic loads. The illustrative example of such analysis of system is introduced. Some attention has been paid to the practical application of the proposed mathematical model.

Structural-Performance Tracking to Multitype Members of Shenzhen Vanke Center in Construction Phase

AbstractThe Shenzhen Vanke Center is constructed of a composite frame and cable system, which is a novel structural system and leads to a tedious, complex, and lengthy construction process. The str...

Experimental study of flush end plate beam-to-column composite joints with precast slabs and deconstructable bolted shear connectors

Composite steel-concrete floor systems represent a ubiquitous structural steel framing system for commercial and industrial buildings in the developed world, which exploit the strengths of reinforced concrete and structural steel both symbiotically and in a complementary fashion. However, as attention is being focused increasingly towards minimising emissions and maximising recycling, these composite systems are problematic for many reasons. This paper describes the results of tests on three full-scale sustainable flush end plate semi-rigid beam-to-column joints and three push-out tests with deconstructable tensioned bolted shear connectors, needed to establish the strength of the shear connection in order to design the joints. For this system, precast concrete slabs having a reduced content of ordinary Portland cement are attached compositely to the steel beam using post-tensioned high-strength friction-grip bolts that are unbolted readily at the life-cycle end of the building. This innovative connection system is proposed to circumvent the high-carbon attributes associated with the demolition of conventional steel-concrete composite framing systems. The push-out tests show that the behaviour of specimens with post-installed bolts in clearance holes is significantly different to that of members with stud shear connectors in slabs cast in situ, and the bolted connectors provide reliable and adequate shear connection to composite beams and joints with precast concrete slabs. The test results show that these composite joints have credible rotation and moment capacities within the recommendations of EC3 and EC4, and that fracture of the joint occurs after substantial rotational deformations had been achieved.

Seismic performance factors for moment frames with steel‐concrete composite columns and steel beams

SummarySteel‐concrete composite moment frames have been shown to be an effective alternative for use as the primary seismic force‐resisting system of building structures. However, little data are available to justify the structural system performance factors (i.e., R, Cd, and Ωo) given in codes to characterize the overstrength and ductility of these systems. Reasonable values for these factors are vital for successful seismic design. Based on a suite of new finite element formulations, this work investigates the behavior of composite special moment frames under seismic loading and develops rational system performance factors according to the Federal Emergency Management Agency P695 methodology. A set of archetype frames, selected to be representative of the range of frames seen in practice, were designed according to current design specifications. Nonlinear static pushover and dynamic response history analyses were performed on the frames to generate the statistical data on the seismic response from which the performance factors are quantified. The results from this investigation enable a better understanding of the variability in collapse performance of composite frame systems and will facilitate more effective designs of these systems. Copyright © 2016 John Wiley & Sons, Ltd.

Experimental study on seismic behaviors of steel-concrete composite frames

Steel-concrete composite frames are seeing increased use in earthquake region because of their excellent structural characteristics, including high strength, stiffness, and good ductility. However, there exist gaps in the knowledge of seismic behavior and the design provisions for these structures. In order to better understand the seismic behaviors of composite frame systems, eight steel-concrete composite frames were designed. These composite frames were composed of steel-concrete composite beams and concrete filled steel tube columns. The axial compression ratio of column, slenderness ratio and linear stiffness ratio of beam to column were selected as main design parameters. The low reversed cyclic loading tests of composite frame system were carried out. Based on test results, the seismic behaviors of composite frames such as failure mode, hysteresis curve, strength degradation, rigidity degradation, ductility and energy dissipation were studied. Known from the test phenomenon, the main cause of damage is the out-of-plane deformation of steel beam and the yielding destruction of column heel. The hysteretic loops of composite frame appear a spindle shape and no obvious pinch phenomenon. The results demonstrate that this type of composite frame has favorable seismic behaviors. Furthermore, the effects of design parameters on seismic behaviors were also discussed. The results of the experiment show that the different design parameter has different influence rule on seismic behaviors of composite frame.