Composite I-beams Research Articles

Experimental Study on Flexural Behaviour of Prefabricated Steel-Concrete Composite I-Beams Under Negative Bending Moment: Comparative Study.

The issues of numerous steel beam components and the tendency for deck cracking under negative bending moment zones have long been challenges faced by traditional composite I-beams with flat steel webs. This study introduces an optimized approach by modifying the structural design and material selection, specifically substituting flat steel webs with corrugated steel webs and using ultra-high-performance concrete for the deck in the negative bending moment zone. Three sets of model tests were conducted to compare and investigate the influence of deck material and web forms on the bending and crack resistance of steel-concrete composite I-beams under a negative bending moment zone. The findings indicate that, compared to a conventional steel-normal concrete composite I-beam, incorporating ultra-high performance concrete into the negative bending zone enhances the cracking load by 98%, resulting in finer and denser cracks, and improves the ultimate bearing capacity by approximately 10%. In comparison to the composite I-beam with flat steel webs, the longitudinal stiffness of the composite I-beam with corrugated steel webs is smaller, which can further enhance the bridge deck's resistance to cracking in the negative bending moment zone, and maximize the steel-strengthening effect of the lower flange of the steel I-beam. Based on the findings of this study, it is recommended to use steel ultra-high-performance concrete composite I-beams with corrugated steel webs due to their superior crack resistance, bending strength, and efficient material utilization.

Shear performance of 25 m full-scale prestressed UHPC-NC composite I-beam without stirrups

The burgeoning preference for prestressed Ultra-High Performance Concrete (UHPC) I-girders without stirrups, stemming from the remarkable tensile strength of UHPC, indicating a promising trajectory for future construction endeavors. This research delved into real-world engineering scenarios, focusing on shear tests conducted on both 9.0m and 6.5m segments cut off a 25.0m full-scale prestressed UHPC-NC composite I-beam without stirrups, which had already undergone flexural failure. Employing Finite Element Models (FEM), the study scrutinized and forecasted test outcomes. In asymmetric loading shear test, the end with a lower shear span ratio and higher shear capacity fails earlier. Subsequently, a validated FEM, reflective of the tested beam, was established. Leveraging this validated model, a comprehensive analysis ensued, probing into parameters influencing the shear performance of the full-scale prestressed UHPC-NC composite I-beam without stirrups. Parameters under study encompassed the prestressed tension level, web width, and shear span ratio. Findings revealed minimal impact of prestressed tension level on the shear performance of the tested beam, with augmented web width substantially enhancing stiffness and shear capacity. Conversely, an increase in shear span ratio correlated with a decline in shear performance of the tested beam. Finally, it juxtaposed various predictive equations for the shear capacity of the beams without stirrups from disparate global locales, advocating for the utilization of equations outlined in the French equation to predict the shear capacity of the tested beams in this study, aiming for minimized margin of error and conservative estimation.

Experimental and analytical investigation of the flexural behavior of steel-bamboo composite I-beams with composite connections

A novel steel-bamboo composite (SBC) I-beam with composite connections was presented, in which the pure adhesive bonding steel-bamboo (SB) interfaces at the beam's flanges were reinforced by self-tapping screws (STSs) to avoid the debonding failure and slip behavior of beams. 14 beams with various parameters were prepared and performed four-point bending tests to investigate the bending behavior of beams. The influences of different parameters on the bending behavior were revealed. Finally, analytical models were developed for estimating the interfacial shear stress at the beam flanges in the serviceability limit state (SLS) and ultimate deflection of beams, respectively. The results indicated that the debonding failure and slip behavior of beams were effectively limited, and the flexural and deformation capacities and ductility were significantly improved. The failure mechanism of beams changed from a debonding failure to a bamboo tensile failure. The bending resistance was improved by increasing the diameter and arrangement range of the STS and reducing the STS spacing and steel flange width-thickness ratio. The local buckling behavior was effectively reduced and the ductility was improved for beams reinforced with transverse stiffening ribs (TSRs). Compared to beams with inclined STS reinforced bonding interfaces, the bending resistance was increased for beams with vertical STS reinforced bonding interfaces. The analytical model provided accurate predictions for beams.

Predicting the fatigue life of T800 carbon fiber composite structural component based on fatigue experiments of unidirectional laminates

This study is based on the fatigue experiment results of unidirectional laminates and investigates the fatigue performance of T800 carbon fiber/epoxy resin composite structural components through experimental and numerical analysis. Fatigue experiments were performed on [0]16, [90]16, and [±45]8 laminates individually, obtaining the fundamental fatigue parameters necessary for modeling. The fatigue life model for T800 carbon fiber/epoxy resin unidirectional laminates was refined, and fatigue degradation rules were provided for the fatigue progressive damage model. A fatigue progressive damage analysis model for T800 laminates was established based on the 3D Hashin criterion, predicting the fatigue life and fatigue damage failure process of the laminates. A fatigue life prediction model was developed for T800 carbon fiber composite I-beam structural components, which can predict the primary types of fatigue failure, fatigue life and the location of fatigue failure occurrence. The predicted fatigue life of structural components shows good consistency with the experimental results. This method can calculate structural components including ply angles of 0°, 45°, and 90° and obtain the fatigue life contour.

Shear strength of steel-concrete composite I-beams with corrugated steel webs

Corrugated steel webs have been widely applied to steel-concrete composite beams due to their excellent shear performance. However, there needs to be adequate research on the shear behavior of steel-concrete composite I-beams with corrugated steel webs, and the proportional distribution of shear forces between concrete flanges and corrugated steel webs in composite I-beams has yet to be clarified. This paper experimentally investigates steel-concrete composite I-beams with corrugated steel webs with different shear span ratios. With the increase of the shear span ratio, the shear failure mode of the beam gradually evolves from shear-dominated to flexural-dominated, the shear capacity and structural stiffness of the beam are negatively affected, and the improvement of the shear resistance of the beam after webs buckling is gradually limited. As the primary shear component, corrugated steel webs contribute about 71 % to 92 % of the total sectional shear force. Notably, accounting for 15 % to 35 % of the shear capacity of the beam, the shear contribution of the concrete flange must also be typically considered. For the generalizability of research results, parametric studies are conducted using validated numerical models to comprehensively investigate the effects of steel yield strength, concrete strength, web thickness, web height, and shear span ratio. Afterward, an efficient analytical model considering the shear capacity of the concrete flange is proposed to estimate the shear strength of composite I-beams with corrugated steel webs. The proposed analytical model agrees satisfactorily with experimental and numerical analysis results. The research results can provide valuable support for designing and optimizing steel-concrete composite I-beams with corrugated steel webs.

Thermo-mechanical coupling failure modeling of 3D four-directional braided composite I-beam under four-point flexure at room temperature, −50°C and 85°C

This paper aims to experimentally and numerically probe thermo-mechanical coupling behaviors of 3D4D (three-dimensional four-directional) braided composite I-beam under four-point flexure. An improved algorithm based on thermo-mechanical coupling constitution model, and mixed failure criterion are devised for modeling thermo-mechanical coupling failure process of 3D4D braided composite I-beam under four-point flexure. Quasi-static four-point flexure tests are, respectively, performed on 3D4D braided composite I-beam at RT (room temperature), −50 ° C and 85 ° C , and mechanical behaviors and failure mechanisms are analyzed and discussed from experiment results. To validate the aforementioned model and algorithm, novel global-local FE (finite element) model is generated and integrated with new algorithm for modeling failure process of 3D4D braided composite I-beam under four-point flexure at three temperatures, and numerical predictions agree well with experimental findings, demonstrating the effective and rational use of the proposed model in the paper.

Experimental and analytical investigation of the shear behavior of steel-bamboo composite I-beams with composite connections

In steel-bamboo composite beams, the debonding failure and slip behavior of steel-bamboo pure bonding interfaces at the flanges often lead to premature failure of beams and underutilization of material strengths. Therefore, a novel steel-bamboo composite I-beam with composite connections was presented in this study, in which the pure bonding interfaces at the beam's flanges were reinforced by self-tapping screws (STSs). 13 beams were designed and fabricated with interface type, shear span-to-depth ratio, height-to-thickness ratios of bamboo and steel at the web, and width-to-thickness ratio of steel at the flange as main parameters. Then, shear tests and theoretical analysis were performed to evaluate the beam's shear behavior. The results indicated that the debonding failure and slip behavior of the beams were effectively limited, and the shear resistance, deformation capacity, and ductility were significantly improved. The shear resistance of beams was improved by reducing the shear span-to-depth ratio, height-to-thickness ratios of the bamboo and steel at the web, and steel flange width-to-thickness ratio. Finally, the developed analytical models can be concluded to be used to accurately predict the interfacial shear stress at the beam flanges in the serviceability limit state (SLS) and ultimate shear capacity of the beams.

Bending Properties of Cold-Formed Thin-Walled Steel/Fast-Growing Timber Composite I-Beams

A cold-formed, thin-walled steel/fast-growing timber composite system has recently been presented for low-rise buildings. It aims to increase the use of fast-growing wood as a green building material in structures, thus contributing to the transformation of traditional buildings. This study proposed a composite I-beam combined with fast-growing radiata pine and cold-formed thin-walled U-shaped steel. A four-point bending test was used to measure the bending properties of steel–timber composite I-beams under various connection methods. Based on experimental results, this study examined the specimen’s failure mechanism, mechanical properties, and strain development. In addition, a method for calculating flexural bearing capacity based on the superposition principle and transformed section method was suggested. It is evident from the results that fast-growing timber and cold-formed thin-walled steel can have significant composite effects. Different connecting methods significantly impact beams’ failure mode, stiffness, and bearing capacity. Furthermore, the theoretical method for calculating the flexural bearing capacity of composite beams differs from the test value by less than 10%. This paper’s research encourages the applications of fast-growing wood as light residential components, and it serves as a reference for the development, production, and engineering of steel–timber composite structural systems.

An inverse method for curing process-induced eigenstrain reconstruction of laminated composites

Accurate acquisition of the curing process-induced eigenstrain distribution is vital for predicting residual stress of laminated composites. In this work we develop a novel inverse method for full-field PIE reconstruction of laminated composites. We design standard laminates to obtain the PIE of unidirectional and woven lamina which are key ingredients of full-field PIE. Then an inverse model is established to accurately calculate lamina’s PIE from the measured residual middle-plane strain and curvature of standard laminates. Full-field PIE of validation laminates are then reconstructed by the obtained lamina’s PIE. Experimental results are in good agreement with the reconstructed results, verifying the accuracy and effectiveness of our proposed method. Finally, we implement the inverse method in accurately reconstructing full-field PIE of a hybrid laminated composite I-beam. We also observe that the PIE is process dependent, indicating that PIE can be used to evaluate the effect of curing process on residual stress.

A comprehensive analysis for real-time shape and strain sensing of composite thin-walled structure

This study presents an effective and reliable shape sensing strategy to model the flat cross section deformation of laminated composite thin-walled structure. The proposed strategy is derived by using the customized isogeometric I-beam elements and Murakami zigzag theory (MZT), named IG-MZT(I). Compared to the traditional reconstruction model, the IG-MZT(I) offers numerous advantages for displacement and strain analysis of composite thin-walled structure such as high-order continuity representation, simple mesh refinement, and fewer strain sensors. Initially, the theoretical framework of composite I-beam element based on the MZT deformation theory is presented. Then, the isogeometric analysis is introduced to approximate the displacement field, and the order of B-spline basis functions can be determined by the constitutive equations.Furthermore, an intuitive strain conversion model is established for solving the geometric complexities in strain measurements. Finally, utilizing a least-square variational function within IG-MZT(I) enables the establishment of the shape sensing formula. Several numerical analyses and experiment results demonstrate the outstanding accuracy and reliability of the proposed approach for reconstructing composite I-beams.Overall,the present model is simple and independent of the traditional composite reconstruction models that require embedded sensors,making the IG-MZT(I)sufficiently general to analyse the composite structure in service.

Effects of Shear Deformation on Flexural Response of Laminated Composite I-Beam

In this paper, a computational approach based on a kinematic model for laminated composite I-section beam is presented. The flexural behavior of laminated composite I-beams is analyzed by using Classical Lamination Plate Theory (CLPT) and the First Order Shear Deformation Theory (FSDT). Based on these theories, a computer programme for analysis of laminated I-beam has been developed in MATLAB. The comparison of results obtained using both theories has been made. It is shown that the shear deformation has significant effect on the deflection of the beam. Furthermore, the laminated I-beam is also modeled using ABAQUS software package for numerical results using different value of load applied at mid-span of the beam. Results obtained using ABAQUS are compared with results obtained with self developed computer program in MATLAB. It is observed that there is good correlation between results obtained from ABAQUS and the computer program before local failure such as buckling of flanges and web occur. Finally, the effect of various parameters such as width-tothickness ratio of flanges, depth-to-thickness of web, and span length-to-depth ratio of I-beam has been investigated. It is concluded that the effect of web depth-to-thickness ratio has little effect on the overall flexural response of I-beam while the width-to-thickness ratio of flanges has significant effect on the flexural response of composite I-beams.

Buckling analysis of laminated composite thin-walled I-beam under mechanical and thermal loads

Despite the extensive use of thin-walled structures, the studies on their behaviours when exposed to extreme thermal environment are relatively scarce. Therefore, this paper aims to present the buckling analysis of thin-walled composite I-beams under thermo-mechanical loads. The thermal effects are investigated for the case of studied beams undergoing a uniform temperature rise through their thickness. The theory is based on the first-order shear deformation thin-walled beam theory with linear variation of displacements in the wall thickness. The governing equations of motion are derived from Hamilton's principle and are solved by series-type solutions with hybrid shape functions. Numerical results are presented to investigate the effects of fibre angle, material distribution, span-to-height's ratio and shear deformation on the critical buckling load and temperature rise. These results for several cases are verified with available references to demonstrate the present beam model’s accuracy.

Prestressed Steel-Concrete Composite I-Beams with Single and Double Corrugated Web

Composite steel girders with concrete have been used for many years and advances in structural and fabrication technology have established their optimization. One of the changes in structural steel I-beams during the past few years has been the availability of web corrugation. The economic design of steel girders normally requires thin webs. Moreover, using externally prestressed tendons as a strengthening technique controls deflections and stresses. However, this strengthening technique causes shear buckling of the steel beams. In this study, the flexural behavior of externally prestressed composite steel-concrete I-beams with a single and double corrugated web was experimentally and numerically investigated. Three simply supported prestressed steel-concrete composite I-beams with single corrugated web (SCW) and double corrugated web (DCW) were tested under four-point loading. The tested beams were externally prestressed by using straight tendons along the full length. The experimental results showed that using SCW was more efficient in shear buckling resistance than DCW with the same equivalent web thickness. The ABAQUAS package was used to simulate the nonlinear behavior of the tested beams. The developed model was validated against the experimental results to carry out a parametric study in order to investigate the effect of various parameters on the behavior of the composite beams with SCW and DCW. Using stiffeners at the loading points as deviators to maintain the prestressed tendon positions increased the beam capacity and improved the beam performance.

Soft impact behavior of composite I-beams

As the increasing requirement of high-strength and lightweight structure in engineering applications, thin-wall I-section beams made of composite materials have drawn much attention in recent years. This paper made an effort to reveal the dynamic behavior of composite I-beams under soft impact. I-beam specimens were manufactured through resin transfer molding and then struck by aluminum foam projectiles. Numerical models were subsequently built up and verified through comparison of deflection and failure types with test results. After modification of the models with more reasonable construction method, parametric study was carried out and structure with the optimal dimensions was chosen. The I-beam was further optimized through adding polyurethane foam in the web. It was proved that the introduction of foam core with proper thickness will prevent buckling of the web and reduce the damage occurred during soft impacts.

Evaluation of Laminated Composite Beam Theory Accuracy.

Carbon fiber-reinforced polymer (CFRP) has been widely implemented in electric vehicle bodies and aircraft fuselage structures. The purpose of CFRP is to reduce the weight and impart rigidity in the final product. A beam structure is typically used to bear the structural load, and the rigidity of the beam can be changed by arranging the laminated fibers at different angles. In this study, a composite I-beam is used as an example in engineering components. Because the theoretical model of the superimposed composite I-beam is established, the theoretical formula is based on the theoretical assumptions of the two-dimensional composite beam, and is combined with the traditional composite plate theory to analyze the maximum bending stress, strain, and deflection. During the theoretical derivation, it is assumed that the flanges of the I-beams are divided into narrow and wide flanges. The beams are considered as structures of beams and flatbeds. When a narrow flange is loaded in the side, the wide flange has no lateral deformation, and the lateral moments are neglected. Therefore, the accuracy of this formula needs to be verified. The purpose of this study is to verify the accuracy of theoretical solutions for the deflection and stress analysis of composite beams. A finite element analysis model is used as the basis for comparing the theoretical solutions. The results indicate that when the aspect ratio of the beam is >15, the theoretical solution will have better accuracy. Without the addition of the material, when 0° ply is placed on the outermost layer of the flange of the nonsymmetric beam, the effective rigidity of the beam is increased by 4–5% compared with the symmetrical beam. The accuracy range of the theoretical solution for the composite beams can be accurately defined based on the results of this study.

Experimental Study on the Flexural Performance of Timber–Steel Composite (TSC) I-Beams

To promote the development of timber–steel composite (TSC) structures, this paper proposes a TSC I-beam with an I-beam as the webs, covered with a timber board on its upper and lower surfaces and bolted together; the effect of varying the ratio of the timber board thickness to I-beam on the bending performance of the TSC I-beam was investigated. Considering the same total height of the beam cross-section and the variation of timber board thickness and I-beam height, three groups of six TSC beam specimens were designed and fabricated to carry out bending load failure tests, and the effects of the variation of timber board thickness with respect to I-beam height on the failure mode, flexural load capacity, ductility, and composite degree of TSC beams were analyzed. In addition, a model for predicting the elastic ultimate bending capacity and mid-span deflection of TSC I-beams was proposed on the basis of the composite coefficient method, which avoids the need to test the joints, and the theoretical calculation results were in good agreement with the test results, which can provide a reference for the design of TSC I-beams.

A general higher-order shear deformation theory for buckling and free vibration analysis of laminated thin-walled composite I-beams

A general higher-order shear deformation theory for buckling and free vibration analysis of laminated thin-walled composite I-beams is proposed in this paper. It is based on a unified nonlinear variation of shear strains in the wall thickness and then theoretical formulation is derived in the general form which can recover the previous conventional theories such as classical and first-order thin-walled beam theory. Series-type solutions with hybrid shape functions are developed for different boundary conditions. Numerical examples are performed on laminated thin-walled composite I-beams with arbitrary lay-ups. Effects of transverse shear strains, fiber angles and slenderness ratio on the critical buckling loads and natural frequencies of the beams are reported.

Bending Failure Behavior of the Glass Fiber Reinforced Composite I-Beams Formed by a Novel Bending Pultrusion Processing Technique

Abstract The glass fiber reinforced resin matrix composite I-beams were designed and formed via a type of novel bending pultrusion processing technique, and the three-point bending tests were carried out to analyze the mechanical bending performances. The obtained results show that the main failure mode of the composite I-beam under the bending load is the upper structure (top flange) cracks along the length direction of the fibers, and the cracks simultaneously propagate downwards in the vertical direction. The bifurcated cracks can be found at the junction area between the top flange and web. In addition, the main bending failure mechanism of the composite I-beam includes the matrix cracking, propagation of cracks, and final fracture failure. In particular, noting that when the crack reaches the I-shaped neck position, the lateral bifurcation occurs, and the resulting secondary cracks further extend in two directions, which leads to the serious damage between the top flange and web, and the ultimate fracture failure occurs.

Analytical Solution of Composite Curved I-Beam considering Tangential Slip under Uniform Distributed Load

An analytical solution of composite curved I-beam considering the partial interaction in tangential direction under uniform distributed load is obtained. Based on the Vlasov curved beam theory, the global balance condition of the problem has been obtained by means of the principle of virtual work; integrating this by parts, the governing system of differential equations and corresponding boundary conditions have been determined. Analytical expressions for the composite beam considering the partial interaction have been developed. In order to verify the validity and the accuracy of this study, the analytical solutions are presented and compared with other three FEM results using the space beam element and the shell element. The deflection and the tangential slip of the composite curved I-beam are investigated.

Experimental investigation on the flexural behavior of laminated bamboo-timber I-beams

I-beams are widely used in construction structures because of their excellent mechanical properties. This research experimentally investigated the flexural performance of composite I-beams made of timber and bamboo to enhance the structural performance of I-beams. A total of six groups of laminated bamboo-timber I-beams with 12 specimens were tested. The laminate materials included bamboo scrimber and Douglas fir. The test parameters included the number and position of the bamboo laminates. Four-point bending experiments were employed to study the failure modes, flexural performance, load-displacement relationships, and strain curves of the bamboo-timber I-beams. The results indicated that the bamboo-timber I-beams mainly showed three failure modes: lower flange tensile failure, web shear failure, and web horizontal penetration crack failure. The load-displacement curves and load-strain curves of all specimens were linear. The deformation capacity of the bamboo-timber beams was significantly improved compared with that of the control timber beams. As the number of layers of the bamboo scrimber increased, the flexural stiffness of the bamboo-timber beams also increased. However, the ultimate bearing capacity of the I-beams was not directly proportional to the number of layers of bamboo scrimber. The bearing capacity and stiffness of the bamboo-timber beams increased by 44.8% and 23.4% on average compared with the control timber beams.