Encased Steel Beams Research Articles

Theoretical Analysis of Composite RC Beams with Pultruded GFRP Beams subjected to Impact Loading

Glass Fiber Reinforced Polymer (GFRP) beams have gained attention due to their promising mechanical properties and potential for structural applications. Combining GFRP core and encasing materials creates a composite beam with superior mechanical properties. This paper describes the testing encased GFRP beams as composite Reinforced Concrete (RC) beams under low-velocity impact load. Theoretical analysis was used with practical results to simulate the tested beams' behavior and predict the generated energies during the impact loading. The impact response was investigated using repeated drops of 42.5 kg falling mass from various heights. An analysis was performed using accelerometer readings to calculate the generalized inertial load. The integrated acceleration record and the measured hammer load vs. time data were utilized to determine the generalized bending load and fracture energy. Four forms of energy were calculated at the maximum load. The total energy was calculated and divided into two parts: The first part was gained by the beam's rotational kinetic energy, the bending energy in the specimen, and the elastic strain energy. The second part was the hammer's kinetic energy before striking the beam. The analytical results showed that the bending energy was less than its rotational kinetic energy for the encased GFRP beams and the reference specimens. In contrast, the encased steel beams had high bending energy due to the higher impact load and deflection. Strain energy recorded lower energy values for all specimens with higher bending energy. There is a good agreement between the tested and the calculated inertial and bending force for all beams. The ratio of inertia force to the total impact load for the encased GFRP and encased steel beams to the reference beam is about 9% and 5%, respectively.

Experimental research on composite deck bridges with encased steel beams

Experimental research on composite deck bridges with encased steel beams

Seismic Behavior of 3D Joint between Concrete Encased Steel Cross-Shaped Column and Steel Beam: Experimental Study

Seismic Behavior of 3D Joint between Concrete Encased Steel Cross-Shaped Column and Steel Beam: Experimental Study

Seismic Behavior of 3D Joint between Concrete Encased Steel Cross-Shaped Column and Steel Beam: Experimental Study

Seismic Behavior of 3D Joint between Concrete Encased Steel Cross-Shaped Column and Steel Beam: Experimental Study

Experimental and theoretical study on flexural behavior of high strength concrete encased steel beams with steel fibers

In this study, the flexural behavior of high strength concrete encased steel beams with steel fibers (HSCSBSF) under bending is investigated. The experiments of four HSCSBSF including one HSCSBSF without steel fiber (0% volume ratio of steel fiber) are carried out to investigate the effect of the volume ratio of steel fiber on the flexural behavior of HSCSBSF. All specimens fail by the yielding of reinforcement in tension zone and the crushing of concrete in compression zone. Due to the positive effect of steel fiber on the internal bonding strength of concrete, HSCSBSF with higher volume ratio of steel fiber shows higher cracking load. The bearing capacity (bending capacity) of HSCSBSF increases by 34.3% when the volume ratio of steel fiber varies from 0% to 2%. Compared with HSCSBSF with 0% volume ratio of steel fiber, the flexural stiffness of HSCSBSF with higher volume ratio of steel fiber is obviously improved and the ductility coefficient (the ratio of the displacement at failure load to the displacement at the yield load) of HSCSBSF with 2% volume ratio of steel fiber increases by 25%. Based on the material test of concrete, a value for the influence coefficient of steel fiber on the tensile strength of concrete is suggested. A model for predicting the bearing capacity of HSCSBSF is then derived from theoretical analysis of HSCSBSF. A good agreement between the proposed model and various test data is made.

Cracking behavior and energy consumption of Steel Fiber Concrete Encased Steel beams

Steel Fiber Concrete Encased Steel (SFCES) beams were subjected to bending to investigate the effect of steel fibers on the behavior of Steel Reinforced Concrete beams with or without steel reinforcement. 18 SFCES beams reinforced with steel fibers, steel reinforcement, or both were cast. The parameters considered in the experiment were (a) the volume percentage of steel fiber (0%, 1%, and 2%), (b) the shear span to depth ratio( s/d = 2.5 and 3.5), (c) the stirrups spacing (180 mm and 360 mm), and (d) the presence or absence of longitudinal reinforcement (2Φ8+2Φ10).The cracking load, crack development, energy dissipation capacity, and ductility of the specimens were investigated. The results illustrate that the cracking load F c, the total energy consumption, and the energy ductility increase with increasing steel fiber volume, and the average improvement with a steel fiber volume increase of 1% can reach 36.5%, 21.2%, and 28.67%, respectively. However, this strengthening effect of steel fibers was weakened due to the addition of steel reinforcement. The influence of the steel fiber volume and reinforcement configuration on each stage of energy consumption was mainly concentrated in the elastic ( E 1) and failure stages ( E 3). Finally, mathematical equations were proposed to predict the cracking load and crack width of the SFCES specimens, which were verified by comparing the predictions with the experiment results.

Numerical and analytical investigations of flexural behaviours of ECC–LWC encased steel beams

By conducting a series of experimental study, the authors recently demonstrated that engineered cementitious composites (ECC) can be employed to encase the compression flanges of structural steel sections to prevent slender flanges from local buckling and lateral torsional buckling of laterally unconstrainted beams. In this context, this paper presents comprehensive numerical and analytical investigations on the flexural behaviour of ECC-lightweight concrete (LWC) encased steel beams with a wide range of steel section geometry (from compact to slender) and steel grade (from normal strength to high strength). In the numerical study, a validated three–dimensional (3D) nonlinear finite element (FE) model was adopted to carry out a parametric study on the flexural capacity of 234 encased beams with different design parameters such as steel grade, ECC and LWC strengths, compactness of steel section, beam depth to width aspect ratio and flange and web thicknesses etc. Furthermore, an analytical model was developed by using the strain compatibility and force equilibrium conditions to predict the load-deformation curves of the encased beams until the flexural failure of the beams. Finally, in order to reduce efforts needed for day-to-day design, a simplified analytical solution was also proposed, and its accuracy was validated.

The Use of Box Cross‐Sections for Railway Bridges with Encased Steel Girders

ABSTRACTIn the area of railway bridges, the use of the superstructure created by reinforced concrete deck with encased steel beams is often a preferred alternative for small spans. Despite of well‐known disadvantages, this type of bridges is still preferred by railway authorities because of their high stiffness and small construction depth. Research on new bridges of this concept is focused in particular on optimization and saving material. The article presents a follow‐up study focused on the optimization and efficiency of the use of existing database of box girders for bridging small spans. The main dimensions of the bridges in the study were based on the already published study. As box cross‐sections, commercially developed and produced beams were utilized. Because of high combined bending and torsion resistance, and advanced fire resistance, as well, they are primarily applied in the building structures. They have not been able to find use in bridges, especially due to higher prices per unit weight. However, similar beams can be produced routinely, so the study can served to point out the possible benefits of applying similarly shaped build‐up cross‐sections. In addition to the material consumption, the influence on stiffness of the bridge cross‐section is also discussed.

Behavior of Partially Concrete Encased Steel Beams Under Cyclic Loading

This paper presents an experimental study of the behavior of partially concrete encased steel beams (PE beams) under seismic loading. The effects of a floor slab in providing lateral and torsional support to the strength and ductility of the beam are also investigated herein. One steel beam and six PE beams were tested herein. The strength development in bare steel beam was insufficient and significant lateral torsional buckling (LTB) was observed. The concrete encasement of the PE beam delayed the occurrence of LTB and hence increased the strength and ductility of the beam. The plastic rotation capacity of PE beam is enhanced by the additional lateral and torsional support provided on the top of a PE beam. For the beam tested in this study, the concrete encasement permits the beam to reach its plastic strength and have plastic rotation of at least 3.42% rad, which is larger than 2% rad required for Intermediate Moment Frames, when no lateral or torsional support is provided at the top of the beam. To satisfy the 4% rad plastic rotation limitation for special moment frames, lateral support with sufficient torsional stiffness is needed.

Effect of Intermediate Stiffeners on the Behaviors of Partially Concrete Encased Steel Beams

Partially concrete encased steel (PE) beams are composite steel beams and concrete elements that present several advantages, such as higher fire resistant, higher flexural capacity, and higher lateral torsional buckling resistant compared to bare steel beams. This paper reports an experimental study of eight PE beams under cyclic loading. The effectiveness of intermediate stiffeners, such as midspan stiffener and plastic hinge zone stiffener, in enhancing composite action and ductility of the PE beams was studied. The ductility performance of PE beams using strengthened beam‐to‐column connection and weakened beam‐to‐column connection was also investigated. The test results show that the plastic hinge zone stiffener performed well and has the potential to replace shear connectors. Strengthened and weakened beam‐to‐column connections can be implemented in PE beams to enhance the ductility of the PE beams; with the details of both strengthened and weakened beam‐to‐column connections determined by bare steel shape instead of the whole section. In addition, the suggestions to prevent premature failure of weakened beam‐to‐column connection were provide.

08.20: Experimental verification of composite action using push‐out tests

ABSTRACTOne of the common types of steel‐concrete composites is the filler‐beam deck bridge with encased steel beams. Steel beams form rigid reinforcement in a longitudinal direction, while such decks are reinforced with secondary cross‐wise reinforcement in a transverse direction. Composite action between the steel and concrete sections is ensured by means of concrete stud connectors. In comparison with the composite action provided traditionally by shear stud connectors, this type of action has higher load‐bearing capacity and fatigue strength, and it is not so labour‐intensive. Great attention is paid to the development of perforated steel strips today. These are employed mainly for the achievement of composite action between a steel beam and concrete slab. To date, a variety of types of composite action have been investigated at the Civil Engineering Faculty of the Technical University of Košice; therefore, the article presented shows some of the test results from push‐out tests performed on various specimens.

Analytical and experimental investigation on the flexural behavior of partially encased composite beams

Composite members have become popular for medium and high rise buildings. This paper presents the results of an experimental and analytical investigation of the partially-encased composite steel beams with and without web openings. The constant parameters included in this study are the cross-sectional area of the specimen, the distribution of web openings in the encased steel beam, and the grade of concrete. The variable parameters included are percentage of steel section and the presence/non-presence of web openings of the encased steel beam. Six composite beams were tested with different steel percentages. The tests were conducted by applying concentrated load acting at mid-span of each composite beam. The experimental results of encased composite beams are compared and the mode failures are discussed. Based on the testing results it was found that, the specimens with web openings provided better performance as compared to that without web openings. Also the existence of web openings in the encased steel beams is effective in enhancing the flexural capacity and the energy absorption. This increases the ductility and hence reduces the weight of structure. A nonlinear finite element analysis is presented to evaluate the flexural behavior of composite beams. The test results are also compared with the finite element software. Good correlations between what was modeled and the actual experimental results have been achieved.

FE modeling and numerical investigation of shallow cellular composite floor beams

The behavior of shallow cellular composite floor beam is normally governed by the shear transfer mechanism at the contact interface between the concrete slab and the encased steel beam, thus by the influence of the two materials. A detailed finite element modeling approach in investigating the structural behavior of shallow cellular composite floor beam is presented. The shear bound at the contact interface between the concrete slab and the steel beam is simulated by using the contact modeling and considering the adhesion, the friction and the local compression at all the contact zones. Both the material and geometric nonlinearities are considered in the FE modeling of the shallow cellular composite beams. The FEA results are calibrated and validated against the test results and the comparisons indicated that the FE analysis procedures with the contact modeling agree well with the test results, and can accurately predict the flexural behavior and the load bearing capacity of the composite slim floor beam. An extensive parametric study is further conducted to investigate all the likely influences of the parameters such as geometric dimensions and the web openings size and spacing on the structural performance of the shallow cellular composite floor beam.

Flexural behaviour of cold formed steel beams with Diagonal stiffener

The adaptability of the different shapes and sizes of section that are available leads to the potential use of Cold Formed Steel as a complete building material. To improve the elastic buckling stress of the whole thin-walled I section including flanges and lips in pure shear, intermediate stiffeners are added. In this paper, the results of the experiments conducted on cold- formed steel beam encased with diagonal stiffened webs with a view to study their flexural strength are presented. A total of 6 specimens were tested. 2 specimens each of cold- formed steel I section, cold-formed steel I section with diagonal stiffeners and cold-formed steel I section with diagonal stiffeners in filled with concrete was used. All the specimens were tested for flexural strength under two point loading by using reaction type vertical loading frame. Ultimate load carrying capacity and ultimate deflection of each type of beam is calculated and compared. From the experimental investigations carried out to study the flexural behaviour of encased cold-formed steel beams with and without stiffeners, it was found that Cold-formed steel section with stiffeners in filled with concrete has resulted in increased resistance to lateral-torsion buckling.

Shear performance of prestressed ultra high strength concrete encased steel beams

Due to the high compressive strength and durability properties of ultra high strength concrete, prestressed ultra high strength concrete beam was used extensively in bridge engineering, but it possessed obvious brittle behavior. Encasing structural steel into it was a good way for alleviating the problem of brittleness. The purpose of this study was to investigate shear performance of prestressed ultra high strength concrete encased steel beams. A total of fifteen prestressed ultra high strength concrete encased steel beams and seven prestressed ultra high strength concrete beams were tested to shear failure under simply supported three-point loading conditions. The primary variables of this investigation included the presence or not of structural steel, shear span-depth ratio, degree of prestress, ratio of stirrup and thickness of web. The shear performance was evaluated based on cracking pattern, load–deflection behavior and shear ductility. Test results showed that prestressed ultra high strength concrete encased steel beams had higher residual shear capacity and post-cracking stiffness as well as by far better shear ductility than prestressed ultra high strength concrete beams. In addition, influence of experimental parameters on the shear performance of prestressed ultra high strength concrete encased steel beams and prestressed ultra high strength concrete beams also was discussed and compared, respectively.

Analysis and Load-carrying Capacity Estimation of Existing Railway Filler-beam Deck Bridges

Abstract In the paper, the actual condition of several existing concrete railway bridges with encased steel beams is discussed. This structural type represents relatively often solution for small span railway bridges in Slovakia. The main conclusions from inspections and in-situ diagnostics are published together with the results of the loadcarrying capacity calculation on the basis of new European codes. Despite of well-known disadvantages, the bridges with filler-beam decks are still demanded by railway authorities because of their big stiffness and small construction depth.

Study on Short Span Deck Bridges with Encased Steel Beams

A study focusing on optimization and efficiency of relatively common solution for small span railway bridges is presented. The superstructure of the bridges is created by reinforced concrete deck with encased steel beams. Especially, flexural behaviour was analysed in the study. Actual bridge cross-sections as well as spans were taken into account. Actions according to new European codes were implemented. Usually, simplified uniform transverse redistribution of load for every one of encased steel girders across bridge cross-sections is practised in global analysis. As concrete slab and steel beams are composed together through encasement into steel concrete composite deck, its real behaviour is strongly influenced by the plate effects. Simplified procedures were compared to the models developed by finite analyses. Different types of steel cross sections have been analysed. Particularly, hot-rolled and built-up steel beams are compared. Moreover, unsymmetrical I-shaped and upside-down T-shaped welded steel sections were investigated. In addition, optimisation aspects based on material consumption as criterion would be presented. Finally, the influence of deck cantilever and cornice on flexural behaviour would be studied.

Analysis of Encased Steel Beams with Hollow Cross-Sections

Encased beams have been used as rigid reinforcement in deck bridges for several decades. Nowadays they are used mainly in railway reconstruction with limited building heights. During the entire period of their exploitation there have not been any changes or modifications in design or structural solution. Recently introduced Eurocodes allow for plastic design in the ultimate limit state. However, standard verifications of such structures indicate the inefficient use of traditional I-beams only. Therefore, deck bridge specimens with beams of alternative cross-section are designed and experimentally verified in the laboratories at the Civil Engineering Faculty of the Technical University in Košice.

Experimental and Analytical Performance Evaluation of Engineering Wood Encased Concrete-Steel Beam-Column Joints

The seismic performance of engineering wood encased concrete-steel (EWECS) beam-column joints is investigated and reported within this paper. Experimental and analytical investigation was carried out on a total of two interior and two exterior beam-column joints. These four beam-column joints typically consisted of an EWECS column and a wood encased steel beam. The primary parameter was the failure modes of the specimens, namely the beam flexural failure and the joint shear failure. The response of the specimens was presented in terms of their hysterisis loop behavior, crack pattern, joint shear distortion, and deformation decomposition ratios. In addition, the results obtained from a three-dimensional nonlinear finite-element analysis simulating their seismic behaviors were also compared with the test data. The finite-element analysis incorporated both bond stress-slip relationship and crack interface interaction at the unbonded connection region. The analytical prediction of joint shear strength was sat...

Experimental Study on Shear Splitting Failure of Full-Scale Composite Concrete Encased Steel Beams

Presented herein is an experimental study that focuses on the shear splitting failure concrete encased steel beams. Nine full-scale specimens were constructed and tested in this study. Significant horizontal cracks along the interface of steel flange and concrete, referred to as the shear splitting failure, appeared in five tested specimens. Observations from the experiments indicate that the steel flange width ratio, defined as the ratio of steel flange width to gross section width, has a dominant effect on the shear splitting failure of composite beams. The tests results reveal that the shear splitting failure occurs when the steel flange width ratio of a composite beam reaches 0.67. The test results also show that the application of shear studs has a positive effect on preventing this type of failure for beams with large steel flange ratio. In addition to the experimental study, a new method for predicting the failure mode of composite beams is proposed. The proposed method gives satisfactory predictions as compared to the test results. Finally, a new equation is derived for the design of the stirrups to prevent shear splitting failure of naturally bonded composite beams.