Steel-concrete Composite Sections Research Articles

Axial slenderness limits for duplex and lean duplex stainless steel-concrete composite columns

The present study is focused on the local stability of concrete-filled and partially-encased stainless steel sections, fabricated from duplex and lean duplex plates, under axial compression. A total of 34 specimens with box, circular, and I-shaped sections are investigated. Geometrical imperfections of the fabricated stainless steel specimens are measured prior to testing. Following the experiments, a comprehensive parametric study is conducted using finite element method. Results of the experiments as well as the parametric study are then synthesised to recommend axial slenderness limits for the investigated section types. The recommended limits are compared with those stipulated by current design specifications for carbon steel-concrete composite sections. The findings are also compared with the previous data available in the literature for austenitic composite sections and the similarities and differences are highlighted and discussed. The experimental and numerical results are further investigated to calibrate effective width relations to exploit the post-local buckling reserve strength of the studied sections. To facilitate the comparison of the findings with current codified requirements and other studies, the recommendations are presented in three notations used typically by the Australian, American, and European standards.

Plastic stress distribution method for predicting interaction strength of steel-concrete composite cross sections

Steel-concrete composite columns are efficient structural members that possess significant strength, stiffness, and ductility. Accurate methods of assessing the strength of these members are necessary to realize their benefits. Several design codes rely on the plastic stress distribution method for computing the cross-sectional strength of composite columns subjected to axial compression and flexural bending. However, there has been limited validation of this method over the wide range of material properties, cross-sectional geometries, and loading conditions to which it is permitted to be applied. This paper presents a study of the behavior of short composite columns and methods of evaluating their strength. The use of the plastic stress distribution method and the strain compatibility method to evaluate the strength of composite columns is validated against detailed fiber cross section analyses and published experimental data. The results of this study indicate that the plastic stress distribution method can yield significantly unconservative strength predictions, especially for encased composite members with high steel yield strengths and high steel ratios. Motivated by these results, a simple modification factor which can be applied to the results of the plastic stress distribution method to achieve greater accuracy was derived. This modification factor is suitable for use in design practice and enables better predictions of the strength of short composite columns.

Optimized dimensioning of steel-concrete composite beams

Abstract The steel-concrete composite sections are often used in civil building in Brazil and around the world. The connection of the steel profile and the concrete slab increases the performance of the composite structural element due to the use of the advantages of each material. In this article, a bar element is used with an interface element for nonlinear analysis of steel-concrete composite beams with partial interaction. The objective is to develop an algorithm that uses this analysis tool to design steel-concrete composite beams looking for project optimized in terms of material costs. Defined spans, supports, ultimate and service load, an optimization algorithm is used to define the dimensions of the rectangular cross section of the concrete slab, I-shaped steel profile, and the reinforcement bars of the concrete slab, so that the quantity of these materials are the minimum to ensure structural safety, considering the ultimate and service limit states. The design constraints are obtained from building code requirements for concrete, steel and composite structures. The objective function is defined as the cost per unit length of the composite beam, obtained from the unit cost of each material, steel, concrete and reinforcement. In the optimization process, the iterative method sequential linear programming is used, in which the nonlinear problem is approximated by a sequence of linear problems, which has its optimum point defined step by step by the Simplex method. Examples of composite beams with ultimate loads defined in the literature were used to validate the implementations. Other examples were analyzed, being evaluated at each iteration the restrictions and objective function to verify the efficiency of the algorithm.

Axial slenderness limits for austenitic stainless steel-concrete composite columns

The use of stainless steel in steel-concrete composite construction is an emerging topic considering the higher durability, corrosion resistance, and fire resistance as well as aesthetic benefits and ease of maintenance of stainless steel compared to carbon steel. In line with this, the present paper reports the results of a series of experimental and numerical investigations on the local and post-local buckling of austenitic stainless steel-concrete composite columns with an aim to propose axial slenderness limits as well as effective width/diameter formulae for these members. Such limits have not yet been established for stainless steel-concrete composite members in international design standards. Three section types, namely, concrete-filled box, concrete-filled circular, and partially-encased I-sections are thoroughly studied. The investigated columns include some of the largest and most slender stainless steel-concrete composite sections studied to date. The obtained results are compared with theory as well as approaches currently in use by international design standards. It is demonstrated that the codified slenderness limits developed for carbon steel-concrete composite columns cannot be directly used for the stainless steel counterparts and modifications are required. The modifications are recommended in light of the findings of the present study. In addition to axial slenderness limits, effective width/diameter formulae are also recommended for the studied section types.

DETERMINATION OF THE LIMIT HEIGHT OF THE COMPRESSED ZONE OF STEEL-CONCRETE COMPOSITE SECTIONS

A brief review of power resistance of cross sections with a complex composition was made using the examples of steel-concrete composite structures. The features and difficulties that appear when calculate steel- concrete composite structures, materials of which have different strength characteristics, are noted. The proce­dure for calculation the limit height of the compressed zone for steel-concrete composite beam section is given.

Local and post-local buckling of fabricated high-strength steel and composite columns

High-strength structural steel plates are being increasingly used as composite columns in tall buildings, bridges and large infrastructure. The presence of concrete infill in these composite sections enhances their local buckling strength, and thus very slender steel plates can be used in their fabrication. This paper presents the results of an experimental study and numerical investigation of the local buckling slenderness limits for high-strength steel plates. A set of sixteen tests were conducted on both hollow steel and steel-concrete composite sections to explore their local and post-local buckling behaviour under axial compression. A numerical model which accounts for the effects of residual stresses and initial geometric imperfections was developed to predict the local buckling and post-local buckling response of box and I-section columns. This model was verified against the test results. Yield slenderness limits obtained from numerical results were compared with existing codes of practice for both hollow steel and composite sections incorporating high-strength steel plates.

Post-fire damage assessment of Korean bridges using thermal–structure interaction fire analysis

To evaluate fire-induced damage to bridge structures, the thermal–structure interaction (TSI) fire analysis method is proposed, verified and applied to examine the behaviour of bridge superstructures with steel–concrete composite sections and prestressed concrete (PSC) exposed to fire loading. The proposed TSI fire analysis consists of two different modelling parts: thermal transfer analysis and thermodynamic structural analysis. The body temperature inside the structure is first calculated using fire curve boundary conditions in an overall non-linear transient thermal transfer analysis. Thermodynamic structural analysis is then performed based on the entire temperature and heat distribution in the structure. To validate the proposed method, comparisons are made with standard fire test results: the temperature distribution and the deflection of the steel–concrete composite superstructure agreed closely with the results of the standard fire test. The proposed fire analysis method is finally applied to two bridges with different superstructures (steel–concrete composite and PSC) damaged by recent fire events in Korea.

Thermal analysis of steel-concrete composite cross sections via CS-ASA/FA

Abstract When exposed to high temperatures, such as in a fire situation, the physical and resistance characteristics of the materials employed in the structure deteriorate as the temperature increases. This fact promotes a considerable loss in the bearing capacity and stiffness of the structural system. The verification of a structure exposed to fire depends primarily and principally on the thermal analysis of the cross section of the structural element. This analysis permits determination of the temperature variation or temperature range in the element from the boundary conditions provided by the fire model adopted. As such, this study had the objective of performing a thermal analysis in a transient regime by means of a finite element method on steel-concrete composite cross sections that are employed in civil construction through use of the Computational System for Advanced Structural Analysis/Fire Analysis (CS-ASA/FA). Two cross sections are analyzed and the results obtained were satisfactory. In addition, different iterative solution processes were adopted in the analysis. Parametric studies were also performed related to the mesh variation of the finite elements and time increase. From the results, it was possible to conclude that CS-ASA/FA can supply the necessary information when a thermo-structural analysis is performed for the evaluation of strength and stiffness losses of the structural material when exposed to fire.

Parameters estimation of Drucker-Prager plasticity criteria for steel confined circular concrete columns in compression

This paper explores the possibility to use Drucker-Prager model in Steel-Concrete composite section. Numerical simulation was conducted using finite element package to simulate the steel-concrete composite section subjected to uniaxial compressive loading. After calibration with experimental study, parametric study was conducted to evaluate the effect of the friction angle and the cohesion constant c on the stress-strain curve of composite section. Empirical relationship between the friction angle and the confined concrete compressive strength was developed and a range of cohesion constant c between 5-10 MPa was suggested for confined concrete strength range of 25 to 100 MPa, respectively.

Parameters estimation of Drucker-Prager plasticity criteria for steel confined circular concrete columns in compression

This paper explores the possibility to use Drucker-Prager model in Steel-Concrete composite section. Numerical simulation was conducted using finite element package to simulate the steel-concrete composite section subjected to uniaxial compressive loading. After calibration with experimental study, parametric study was conducted to evaluate the effect of the friction angle and the cohesion constant c on the stress-strain curve of composite section. Empirical relationship between the friction angle and the confined concrete compressive strength was developed and a range of cohesion constant c between 5-10 MPa was suggested for confined concrete strength range of 25 to 100 MPa, respectively.

Developments and Prospects of Long-Span High-Speed Railway Bridge Technologies in China

Abstract With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including combined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railway bridges are provided.

An Experimental Verification on the Compressive Behavior of Corrugated Steel Plates and Concrete Composite Section

An Experimental Verification on the Compressive Behavior of Corrugated Steel Plates and Concrete Composite Section

Finite element analysis and parametric study of continuous steel–concrete composite beams stiffened with post-tensioned tendons

Externally post-tensioned tendons can cause an initial compressive stress in steel–concrete composite sections at the hogging moment region, and then a part of the tensile stress in the concrete fl...

Cost Analysis of RCC, Steel and Composite Multi-Storied Car Parking Subjected to High Wind Exposure in Bangladesh

Steel-concrete composite constructions in Bangladesh are nowadays very popular owing to their advantages over conventional concrete and steel constructions. Concrete structures are massive and allot more seismic weight and less deflection whereas steel structures instruct more deflections and ductility to the structure, which is beneficial in resisting earthquake and wind forces. Composite construction combines the better properties of both steel and concrete along with lesser cost, speedy construction, fire protection etc. The objective of this study was to analysis and design ground floor plus 19 storied R.C.C, Steel and Composite (steel-concrete) multi-storied parking structure’s frame of same plan using ETABS 2013 software and compare their structural parameters with estimated cost for required material. All frames are designed for same gravity and dynamic loadings. The RCC deck-slab is used in steel and composite frame. Beam and column sections are made of RCC, steel or steel-concrete composite sections. The composite construction option provided about 25 % and 18% less cost when compared to RCC and steel structure, respectively. Comparative study concludes that the composite frames are best suited among all the three types of constructions in terms of material cost and benefit added with better structural behaviour.

NUMERICAL SIMULATION ON STRESS WAVE PROPAGATION OF STEEL-CONCRETE COMPOSITE STRUCTURES WITH INTERFACE DEBONDING BY SPECTRAL ELEMENT METHOD

To investigate the elastic stress wave propagation in steel-concrete composite structures, a 2 dimensional spectral element model for steel-concrete composite sections was established and the elastic stress wave propagation in the hybrid section with and without interface debonding defects was simulated under single point excitation. The interface debonding was simulated by removing concrete elements between steel tube and concrete core. The wave field and displacement responses of different nodes between the models with and without defects were compared to explain the effect of interface debonding on elastic stress wave propagation. Finally, the displacement responses of different numerical models with different levels of interface debonding were compared to investigate the relationship between the displacement response and the interface debonding defects. Spectral element method (SEM) provides an efficient way for the stress wave simulation of steel-concrete composite structures, which is helpful for the study on the mechanism for interface debonding detection of steel-concrete composite structures based on stress wave measurement.

Hot-Rolled Steel and Steel-Concrete Composite Design Incorporating Strain Hardening

Current design codes for steel and steel-concrete composite structures are based on elastic, perfectly plastic material behaviour and can lead to overly conservative strength predictions due to the neglect of the beneficial influence of strain hardening, particularly in the case of stocky, bare steel cross-sections and composite beams under sagging bending moments. The Continuous Strength Method (CSM) is a deformation based design method that enables material strain hardening properties to be exploited, thus resulting in more accurate capacity predictions. In this paper, a strain hardening material model, which can closely represent the stress-strain response of hot-rolled steel, is introduced and incorporated into the CSM design framework. The CSM cross-section resistance functions, incorporating strain hardening, are derived for hot-rolled steel sections in compression and bending, as well as hot-rolled steel-concrete composite sections where their neutral axes lie within the concrete slab in bending. Comparisons of the capacity predictions with a range of experimental data from the literature and finite element data generated herein demonstrate the applicability and benefits of the proposed approach.

Fire performance of innovative steel-concrete composite columns using high strength steels

This paper presents the results of a numerical investigation on strategies for enhancing the fire behaviour of concrete-filled steel tubular (CFST) columns by using inner steel profiles such as circular hollow sections (CHS), HEB profiles or embedded steel core profiles. A three-dimensional finite element model is developed for that purpose, which is capable for representing the various types of sections studied and the nonlinear behaviour of the materials at elevated temperatures. High strength steel is considered in the numerical model, as a possible way to lengthen the fire endurance. The numerical model is validated against experimental results available in the literature for various types of steel-concrete composite sections using inner steel profiles, obtaining satisfactory results. Based on the developed numerical model, parametric studies are conducted for investigating the influence of the cross-sectional geometry and the steel grade of the inner profiles on the fire performance of these composite columns, for eventually providing some practical recommendations.

PERFORMANCE ANALYSIS OF RCC AND STEEL CONCRETE COMPOSITE STRUCTURE UNDER SEISMIC EFFECT

The RCC Structure is no longer suitable because of increased dead load, span rejection and less stiffness .The structural engineers are trying to use different materials for most efficient design solution .There is great potential for increasing volume of steel in construction .The percentage of steel can be increased with the use of steel-concrete composite sections. The paper presents the effect of FEC (Fully Encased Composite) on a G+ 20 storey special moment frame .In this paper two different structures are considered for the comparison under seismic analysis. The linear static analysis and nonlinear static analysis i.e. “Pushover analysis” are done for G+20 storey structure. The building is analyzed and design for seismic loading by using ETAB software. The unique method of pushover analysis is followed with the help of FEMA 36 specifications and for hinge formation ATC40 is considered. Results are compared for the Base shear, Modal time period, Storey displacement and storey drift for both structures. As the composite is having more lateral stiffness, the results of time period and storey displacement shows the significant variation. While analyzing for “Non-linear static analysis the performance point for the FEC is significantly much more as compared to the RCC model.

Structural analysis and design of a multispan network arch bridge

This paper presents a study of a typical 1·1 km bridge in the north of Italy against a background of new infrastructure development. The bridge is composed of five network steel arches. The design solution represents a lightweight alternative if compared to traditional arch bridges. Every network arch spans 130 m, is 17 m wide and has a maximum height of 25·5 m. The deck is a steel–concrete composite section resting on precast slabs. Hangers have a variable inclination according to the geometric optimisation analysis performed. Before the final structural design, parametric studies were developed in order to optimise the material grade, the structural shape and the structural detailing.

Longitudinal force in continuously welded rail on long-span tied arch continuous bridge carrying multiple tracks

Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube (CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a (77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail (CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load. Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.