Strong Axis Bending Research Articles

Effect of joint behaviors on the load-carrying capacity of single-layer reticulated dome

The majority of previous studies have primarily focused on the impact of nodal deviation or joint’s strong axis bending stiffness of semi-rigid single-layer reticulated shell, ignoring the effect of other kinds of joint stiffness and its interaction with joint size and nodal deviation. Therefore, the single-layer reticulated dome considering all kinds of joint stiffness and joint size is established initially. Subsequently, a comprehensive investigation is conducted to analyze the effect of all types of joint stiffness of improved bolt-column (IBC) joints, as well as joint size and nodl deviation, on the load-carrying capacity of dome. Finally, the coupling effect among these factors on the mechanical performance of dome is also determined. The main conclusions obtained are presented as follows: (I) the axial stiffness of the IBC joint significantly influences the load-carrying capacity of single-layer reticulated dome, resulting in an average decline ratio of 27 %; however, the other types of joint stiffness have a negligible impact, with an average effect of only 1 %. Moreover, the limit load of the dome considering practical stiffness of IBC joint can achieve the 61 % of that of rigid dome; (II) rigidly joined domes with nodal deviations of S/300, S/600, S/900, S/1200 and S/1500 exhibit decline ratios of 0.57, 0.47, 0.41, 0.37 and 0.34, respectively, in load-carrying capacity compared to perfect domes. Moreover, when considering the coupling effect of joint stiffness, joint size and nodal deviation on the load-carrying capacity of the domes, these nodal deviations affect the capacity by 0.65, 0.57, 0.52, 0.49 and 0.46.

Pin-ended stainless steel equal-leg angle section members under compression and major-axis bending: Experimentation, FE modelling and design

The behaviour and design of cylindrically-pinned stainless steel equal-leg angle section members under compression and compression combined with strong-axis bending are investigated herein. An experimental investigation, including material testing, initial geometric imperfection measurements and physical tests on hot-rolled stainless steel equal-leg angle section members is first presented. Numerical models are developed by means of shell finite element modelling formulated within ABAQUS and validated against experimental data. A numerical parametric study is then presented considering both hot-rolled and cold-formed stainless steel equal-leg angle section columns alongside beam–columns with a wide range of cross-section and member geometries. Finally, new design proposals for cylindrically-pinned stainless steel equal-leg angle section members under compression and compression plus major-axis bending are developed and verified against the results of physical experiments and numerical simulations. The proposed design rules are shown to offer substantially more accurate and consistent resistance predictions compared to existing codified design rules. The reliability of the new design provisions, with a recommended partial safety factor γM1=1.1, is verified following the EN 1990 procedure.

Effect of joint stiffness on the load-carrying capacity of single-layer cylindrical reticulated shell with improved bolt-column (IBC) joint

To enlarge the application of single-layer reticulated shells, this study proposes an innovative semi-rigid joint based on the original bolt-column (OBC) joint, referred to as the improved bolt-column (IBC) joint. The mechanical behavior of the IBC joint under the pure load and the coupling effect of bending and axial force is investigated using numerical tests. Then, the practical analytical model of IBC joint is developed based on a three-parameters power model and component method. Subsequently, a mechanical model considering joint stiffness is developed to establish semi-rigidly connected single-layer cylindrical reticulated shell. A total of 456 numerical models of shells are conducted to examine the impact of different kinds of joint stiffness on the load-carrying capacity of shells systematically. The results demonstrate that (i) weak axis bending stiffness and axial stiffness significantly affect the load-carrying capacity of shells by approximately 19 % and 14 % on average respectively; (ii) strong axis bending stiffness and torsional stiffness have relatively minor effects on the critical load of shells, with average decline ratios of only 5 % and 6 % respectively; (iii) out-of-plane shear stiffness and in-plane shear stiffness exhibit negligible impacts on the load-carrying capacity of shells, with an average effect not exceeding 1 %. Finally, the findings of numerical simulation considering all stiffness of IBC joint reveal insights into both varying laws of load-carrying capacity and failure modes for shells. It is observed that the mean critical load can reach up to 59 % of the one of rigidly-connected shells, which is significantly higher than those observed in shells with pinned joints.

Global and Local Geometrical Imperfections of Pultruded GFRP Profiles Based on a Modal Approach

The ultimate capacity of pultruded glass fibre reinforced polymer (pGFRP) profiles depends significantly on geometrical imperfections (GIs), given their sensitivity to buckling phenomena arising from both thin walls and low elastic moduli. However, GIs are not yet comprehensively addressed in design guidance. This paper proposes a new approach to characterize the initial GIs of pGFRP profiles based on a modal approach. Given the lack of comprehensive knowledge in this area, this study presents a highly accurate and robust methodology to measure GIs and dimensional deviations (DDs) in pGFRP profiles using a 3D contact coordinate measurement machine (CMM). The modal approach encompasses the measurement of dimensional parameters and a point cloud transformation that enables the assessment of GIs associated with pure buckling modes of pGFRP profiles. This procedure allows the quantification of three types of global GIs associated to (i) minor-axis (weak axis), (ii) major-axis (strong axis) bending, and (iii) twist. Additionally, the procedure also includes the assessment of local GIs, considering the wall (plate-like) imperfections. The separation of GIs into these four types (shape and amplitude) is of major relevance as its paves the way to the development of analytical design formulas for the strength prediction of pGFRP members. The approach described in this paper also serves two important purposes: (i) the statistical analysis of DDs and GIs of pGFRP members, and (ii) the identification of distinct shapes and amplitudes of GIs that form the basis for reliable design considerations of pGFRP members.

Effect of pile orientation on the fatigue performance of jointless bridge H-piles subjected to cyclic flexural strains

This paper explores the effect of pile orientation on the low cycle fatigue (LCF) performance of steel H–piles (SPs) at jointless bridge (JB) abutments via experimental testing and finite element simulation. The experimental testing program includes 42 full scale SP specimens subjected to strong axis (SA) and weak axis (WA) bending. The SPs are tested under cyclic displacement reversals mimicking the thermal induced displacement cycles associated with the seasonal elongation and contraction of the JB in the summer and winter times. The magnitude of the axial load is also kept as a variable in the experimental testing program to investigate its effect on the cyclic performance of JB SPs. The test results are then verified via finite element simulation and a parametric numerical study is performed to further understand the cyclic behavior of SPs as a function of numerous parameters. The tests and numerical analyses results revealed that for identical cyclic flexural strain amplitudes, SPs oriented for WA bending generally demonstrate a superior performance in terms of LCF life in the presence of axial loads compared to those oriented for SA bending. Moreover, the research results showed that at large flexural strains, local buckling becomes more critical than the pile orientation for the LCF life of SPs in JBs.

Construction and Live Load Behavior of a Skewed Steel I-Girder Bridge

As part of a long-term monitoring project, a two-span continuous steel I-girder bridge (skewed 41° with seat-type abutments) was instrumented and evaluated in the field during construction and after the bridge was in service. This paper discusses data from when the first stage (of a three-stage sequence) was constructed and initially opened to traffic. Girders and cross-frames were instrumented with strain gauges using a data acquisition system with a high sampling frequency (up to 20 Hz). Data collection began just before deck placement, and a series of live load tests was then conducted on the completed Stage I (half of the bridge) using a loaded truck. Three-dimensional finite element analyses were carried out to provide enhanced understanding of bridge behavior. Good agreement was observed between the numerical simulation results and the field monitoring data for both deck placement and live load testing. A slight inconsistency between numerical simulation and field measurement data at one girder section and an adjacent cross-frame indicated an unexpected local site condition, which was confirmed through a targeted field inspection. Live load distribution factors used during design conservatively overestimate bridge girder strong-axis bending response under live load (by around 50%). Maximum flange lateral bending stresses of 6.3 MPa (0.9 kips per square inch [ksi]) and 2.5 MPa (0.4 ksi) were observed during deck placement and truck tests, respectively. In addition, out-of-plane response of 10.6 MPa (1.5 ksi) was observed at girder web plates under concrete dead load.

A generic method for assessment of inhomogeneous wave load effects of very long floating bridges

Floating bridges are promising infrastructures used to cross wide and deep fjords. During the design of floating bridges, the wave field is usually assumed long-crested and homogeneous. However, the real wave field in fjords is short-crested and inhomogeneous due to the complicated topography. To evaluate the uncertainties implied by the homogeneous assumption, a generic method is proposed in this study for the assessment of inhomogeneous wave load effects of very long floating bridges. The inhomogeneous wave field is represented by the long-term variation and correlation of wave spectral parameters at the location of each pontoon and by coherence functions of wave elevations between pontoons. The correlated and inhomogeneous wave field is simulated by applying the Cholesky decomposition techniques based on auto- and cross-spectra of waves at pontoons. The wave spectral parameters can be determined with consideration of their long-term correlation while the coherence functions of wave elevations can be obtained by using phase-resolved methods. Based on the simulated wave elevations at each pontoon, the time series of first-order and second-order wave excitation forces are created by using the transfer functions and applied externally to each pontoon in the numerical model of the floating bridge. The proposed method is validated and applied to investigate the dynamic behavior of a floating bridge for the Bjørnafjord crossing as a case study. The inhomogeneous wave load effects are assessed by carrying out fully coupled time-domain simulations. It is found that the assumption of homogeneous wave conditions is conservative for the strong axis and weak axis bending moments, but significantly nonconservative for the axial force. The proposed method can also be applied for other very large floating structures subjected to the inhomogeneous wave field.

Investigating the redundancy of steel truss bridges composed of modular joints

The objective of this paper is to present a numerical investigation of the redundancy of steel truss bridges composed of novel modular joints when subjected to the sudden loss of diagonal members. The modular joint - a prefabricated steel nodal connector composed of flat web plate welded to flat and curved cold bent flange plates - represents a new approach to the construction of steel truss bridges in which the connector is a module that joins member that are standard rolled wide flange sections. A unique feature of this approach is that a moment-resisting connection is achieved in a truss topology by joining webs and flanges independently through bolted splice connections. This, in combination with orienting members in strong axis bending, provides the potential for the system to tolerate the loss of a diagonal member through load redistribution in flexure. The response of a 119-m (390-ft) simply supported vehicular bridge following the abrupt loss of a diagonal is numerically investigated considering three behaviors: (1) instantaneous dynamic behavior, focusing on the effect of the high-velocity stress wave, with its associated high strain rates and impact on fracture toughness particularly in the cold bent and welded portion of the modular joint, (2) short-term dynamic behavior of the structure, and (3) static behavior of the faulted structure. Results show that the modular joint is able to redistribute load after sudden member loss, demonstrating the redundancy of this new approach to modular construction.

Experimental investigation of C-shaped glass-fiber-reinforced polymer connectors for sandwich insulation wall panels

A kind of C-shaped glass-fiber-reinforced polymer (GFRP) connector for panels was proposed and experimentally investigated in this study. The connector was extruded into C-shape with anchorage rebars at ends. The C-shaped GFRP connector has large stiffness and bearing capacity, allowing sufficient connection between panels with high thickness insulation layers. Shear, tensile, and compression tests were conducted to quantify the performance of connectors under different loading conditions. The length and loading direction of the connectors were main parameters investigated by shear testing. As the connector’s length increased, the failure mode of the connector with strong-axis bending tended to be anchorage failure instead of connector failure. The failure mode of the connector with weak-axis bending tended to be connector failure in the 60–300 mm length range. Equations were derived to predict the damage mode of the connector system. The results from tensile testing and compression testing revealed an anchor failure mode related to the anchorage rebars and concrete. Such C-shaped GFRP connector design was also capable of resisting the force and displacement of panels with a thick insulation layer up to 300 mm.

Cyclic testing of bolted base connections for wide-flange columns

This research focused on a new type of bolted base connection for wide-flange columns. The base connection consists of a pair of steel angles and a shear plate that connect the wide-flange column to the foundation. To investigate the behavior of the base connection under the combined column axial compression and cyclic lateral load causing the strong-axis bending in the column, six experimental specimens were designed, constructed, and tested. The test parameters varied in the specimens included the column axial compression and the technology used to manufacture the angles used in the bolted base connection. All the specimens were tested using the same cyclic lateral loading protocol. It was found that all the specimens behaved in the same ductile manner while dissipating significant amounts of hysteretic energy. Moreover, all the specimens stably achieved the ultimate connection rotation of 0.06 rad without experiencing any in-cycle strength degradations. This investigation experimentally demonstrated the replaceability of the angles in the bolted base connection. The tests also provided clear evidence that the hot rolled, cold folded and welded angles can be alternatively used in the bolted base connection to sustain the connection rotation up to 0.06 rad. This research further derived a simplified analysis model to capture the backbone response of the bolted base connection. Result comparisons show that the analysis model can provide reasonable approximations.

Efficient application of the Reduced Stress Method for built-up I sections

Reduced Stress Method is an alternative to the effective width method of EN 1993-1-1. Because of its built-in conservatism it is less used in practice for the design of building structures. The proposed new application reduces this conservatism. The final stress distribution is obtained with a 2-step iteration which automatically handles the effect of the displacement of the center of gravity of the original gross cross-section. Instead of calculating effective widths or reducing the whole cross-section resistance, reduced thicknesses are assigned to the proper individual plates. Reduction is obtained using the standard plate buckling curves where the plate slenderness is calculated with the help of linear buckling analysis. The buckling shape relevant to each plates of the cross-section is selected with a deformation energy-based buckling sensitivity analysis. The proposed method is demonstrated on a series of welded I beam-column Class 4 sections subjected to constant axial compression force and strong axis bending moment. Resistances are compared with results obtained by the EN 1993-1-3 effective width method and by numerical simulation. The method is ready to be built into computer software which can handle shell finite elements and perform linear buckling analysis.

Elastic and inelastic buckling of steel cellular beams under strong-axis bending

This paper presents an extensive parametric study of elastic and inelastic buckling of cellular beams subjected to strong axis bending in order to investigate the effect of a variety of geometric parameters, and further generate mass data to validate and train a neural network-based formula. Python was employed to automate mass finite element (FE) analyses and reliably examine the influence of the parameters. Overall, 102,060 FE analyses were performed. The effects of the initial geometric imperfection, material nonlinearity, manufacture-introduced residual stresses, web opening diameter, web-post width, web height, flange width, web and flange thickness, end web-post width, and span of the beams and their combinations were thoroughly examined. The results are also compared with the current state-of-the-art design guidelines used in the UK.It was concluded that the critical elastic buckling load of perforated beams corresponds to the lateral movement of the compression flange while the most critical parameters are the web thickness and the geometry of the flange. However, from the inelastic analysis, the geometry and position of the web opening influence the collapse load capacity in a similar fashion to the geometry of the flange and thickness of the web. It was also concluded that the effect of the initial conditions was insignificant.

Extreme responses and associated uncertainties for a long end-anchored floating bridge

Very-long floating bridges represent an innovative marine structure for crossing wide and deep fjords. During the design of a floating bridge, extreme structural responses at a specified probability of exceedance are required to be properly evaluated for ultimate limit state (ULS) design check. This study addresses the estimation of extreme structural responses due to wind and wave loads and associated uncertainties. An end-anchored floating bridge, about 4600 m, is considered in a case study. The long-term extreme responses are estimated by using a simplified engineering approach, in which the long-term extreme response is approximated by the one-hour short-term extreme responses at a high fractile (90% in this study) for selected short-term sea states. The extreme responses are expressed as μ+κ·σ, where μ and σ are the ensemble mean and standard deviation, and κ is a multiplying factor. Statistical analyses indicate that the structural responses, including axial force, strong and weak axis bending moments of the bridge girder, are close to follow a Gaussian distribution. A simplified analytical method, the Gumbel method and the mean upcrossing rate (MUR) method are employed to estimate the multiplying factor κ and extremes. The κ estimated by these three methods are generally close, varying in the vicinity of 4. The κ and extremes estimated by the simplified method have a much smaller variation than the Gumbel and MUR methods. Statistical uncertainties and model uncertainties in the extreme value prediction are also addressed. Based on the results of 10 sets of 10 1-h ensembles, the mean and coefficient of variation (CoV) of μ,κ,σ and extremes of structural responses of 10 1-h simulations under two selected sea states are evaluated. The CoV of σ is less than 0.045, but the CoV of κ is relatively large, mainly between 3.5×10-2 and 6.5×10-2. The CoV of extremes estimated by the simplified analytical method is fairly small, less than 0.035. While the CoV of extremes estimated by the Gumbel and MUR methods are much larger and can reach 0.137 and 0.158, respectively. In practical design of floating bridge, only a limited number of simulations (e.g. 10 1-h) are conducted to predict the extreme structural responses. This will introduce statistical uncertainties and should be corrected by a factor for a conservative estimate. A simplified procedure to derive the correction factor is presented in this study. For the floating bridge considered with 10 1-h simulations, the correction factor is recommended to be 1.1 when the absolute value of mean μ is smaller than σ, and be 1.2 when the absolute value of mean μ is larger than σ, in order to achieve a 90% conservative estimation of extreme.

Performance of segmental self-centering rubberized concrete columns under different loading directions

Segmental self-centering columns are an advantageous construction choice in earthquake prone areas due to their minimal or even zero residual deformation and their low repair/downtime costs. This research investigated the behavior of segmental rectangular column members with a high cross-sectional length to width ratio under different loading directions, with the aim of potentially extending the concept of segmental self-centering columns to wall members, such as shear walls and retaining walls. The main parameters of this study were the direction of loading: in-plane (strong-axis bending) and out-of-plane (weak-axis bending), provision (or absence) of reinforcement, and the type of concrete material (conventional concrete or rubberized concrete). Eight concrete columns with a cross-sectional length to width ratio of 2.5 and consisting of three concrete segments with dry joints in between, were tested under reversed-cyclic lateral loading. A pre-stressing force of 100 kN, corresponding to a stress of 2.8 MPa on the column, was applied using unbonded post-tensioning (PT) bars. The results indicated that although in-plane loaded columns had a higher load capacity, they exhibited a less ductile response, higher level of damage and higher loss in the PT force, compared with the out-of-plane loaded columns. The total equivalent viscous damping and its variation was very small in all tested specimens, and it increased slightly as the drift ratio increased. Empirical equations were developed to express the damping as a function of drift ratio. It was also concluded that in the out-of-plane loaded specimens, the effect of reinforcement on the load-displacement response was insignificant. In rectangular columns with high length-to-width ratio, under out-of-plane loading, if a minimum level of axial pre-stressing is applied (to prevent shear or sliding failure), no structural reinforcement is required. In addition, the strength reduction due to using rubber in concrete at the structural level was much lower than that at the material level. The results of this study can potentially be applied to segmental concrete walls due to the high length-to-width ratios of the tested columns.

Numerical Modeling and Dynamic Analysis of a Floating Bridge Subjected to Wind, Wave, and Current Loads

Designing reliable and cost-effective floating bridges for wide and deep fjords is very challenging. The floating bridge is subjected to various environmental loads, such as wind, wave, and current loads. All these loads and associated load effects should be properly evaluated for ultimate limit state design check. In this study, the wind-, wave-, and current-induced load effects are comprehensively investigated for an end-anchored curved floating bridge, which was an early concept for crossing the Bjørnafjorden. The considered floating bridge is about 4600 m long and consists of a cable-stayed high bridge part and a pontoon-supported low bridge part. It also has a large number of eigen-modes, which might be excited by the environmental loads. Modeling of wind loads on the bridge girder is first studied, indicating that apart from aerodynamic drag force, aerodynamic lift and moment on the bridge girder should also be considered due to their significant contribution to axial force. Turbulent wind spectrum and spatial coherence play an important role and should also be properly determined. The sway motion, axial force, and strong axis bending moment of the bridge girder are mainly induced by wind loads, while the heave motion, weak axis bending moment, and torsional moment are mainly induced by wave loads. Turbulent wind can cause significant larger low-frequency eigen-mode resonant responses than the second-order difference frequency wave loads. Current loads mainly contribute damping and reduce the variations of sway motion, axial force, and strong axis bending moment.

Lateral torsional buckling of STEEL beams strengthened with GFRP plate

The present study investigates the lateral-torsional buckling of wide flange steel members strengthened by a Glass Fiber Reinforced Polymer (GFRP) plate bonded to one of the flanges through an adhesive layer. A variational formulation and two finite elements are developed for the problem. The formulation captures global and local warping effects, shear deformation due to bending and twist, and partial interaction between the steel and GFRP provided by the flexible layer of adhesive. The destabilizing effects due to strong axis bending, axial force and load height effect are incorporated into the formulation. The first element involves two nodes and 16 buckling degrees of freedom (DOFs) while the second element involves three nodes and 14 DOFs. Comparisons of present model results against those based on 3D finite element analysis based on solid elements demonstrate the ability of the present models to accurately predict the buckling loads and mode shapes at a fraction of the modelling and computational efforts. Practical examples quantify the gain in elastic buckling strength achieved by GFRP strengthening, and characterize the moment gradient factors and load height effects. Elastic buckling interaction diagrams are developed for beam-columns and comparisons are provided to interaction diagrams of un-strengthened beams.

LOAD-MOMENT INTERACTION DIAGRAMS OF SLENDER PARTIALLY ENCASED COMPOSITE COLUMNS

Partially Encased Composite (PEC) Columns consist of thin-walled built-up H-shaped steel sections with links welded near the flange tips and concrete cast between the flanges. To predict the strength and ductility of slender PEC columns, Newmark’s numerical iterative procedure is implemented. Overall column slenderness ratio, flange plate slenderness ratio and concrete strength are the selected parameters to observe the variation of strength and ductility of slender PEC column. Bending of column about both the strong and weak axis is considered to observe the significance of the selected parameters. In strong axis bending, a decrease in strength is found with the increase of overall slenderness ratio and flange plate slenderness ratio. Again, failure envelope of column strength curve becomes smaller with the increase of overall slenderness ratio. It implies the ductility of slender PEC column decreases with the increase of the overall slenderness ratio. Moreover, similar behaviour is observed with the increase of flange plate slenderness ratio. As the strength of concrete increases, strength of slender PEC column is observed to increase by significant amount. Similar behaviour is observed in weak axis bending along with some drop in strength

Wave load effect analysis of a floating bridge in a fjord considering inhomogeneous wave conditions

When designing a floating bridge crossing a deep and wide fjord, a homogeneous wave field is usually assumed for simplicity. However, waves in fjords are commonly inhomogeneous, and hence the mentioned design practice introduces uncertainty, which should be assessed for the design. In this study, we proposed an approach to account for the inhomogeneous wave load effect on a floating bridge and applied it on a floating bridge that was initially proposed for crossing the Bjørnafjorden. The floating bridge considered is end-anchored, about 4600 m long and consists of a cable-stayed high bridge and a low bridge supported by 19 pontoons. Wave excitation loads on each pontoon were proposed to be modeled and applied separately to account for inhomogeneous waves. By considering 1-year and 100-year wave conditions, dynamic responses of the floating bridge subjected to homogeneous and inhomogeneous waves were analyzed and compared. It is found that inhomogeneous waves cause relatively larger sway motion, axial force, and strong axis bending moment, as well as significantly larger weak axis bending moment along the bridge girder than homogeneous waves. These responses depend on the inhomogeneity level of waves considered. Proper description of the wave field is therefore very important for evaluating the effect of inhomogeneous waves and associated uncertainties.

Hydrodynamic load modeling and analysis of a floating bridge in homogeneous wave conditions

The Norwegian Public Road Administration (NPRA) is currently developing the E39 ferry-free project, in which several floating bridges will be built across deep and wide fjords. In this study, we consider the floating bridge that was an early concept for crossing the Bjørnafjorden with a width of about 4600 m and with a depth of more than 500 m. The floating bridge concept is a complex end-anchored curve bridge, consisting of a cable-stayed high bridge part and a low bridge part supported by 19 pontoons. It has a number of eigen-modes, which can be excited by wave loads. Wave loads and their effects should thus be properly modeled and assessed. Therefore, the effect of hydrodynamic load modeling are investigated in homogeneous wave conditions, including varying water depth at the ends of the bridge, viscous drag force on pontoons, short-crestedness and second order wave loads. It is found that the varying water depth has negligible effect, while the other features are important to consider. Second order difference-frequency wave loads contribute significantly to sway motion, axial force and strong axis bending moments along the bridge. However, these effects can be reduced by viscous drag forces, which implies that an appropriate model of viscous drag force effect on the pontoons is important. short-crested waves greatly affect the heave motion and weak axis bending moment. All these considerations on hydrodynamic load modeling are further applied to analyze the wave load effect of a floating bridge in a fjord considering inhomogeneous waves [1].

Ultimate strength of H-sections under combined compression and uniaxial bending considering plate interaction

The ultimate strength and behavior of steel H-sections are investigated experimentally and theoretically in this paper. The main considered parameters include different combinations of flange and web width-to-thickness ratios and varying axial force ratios, with both major and minor axis bending responses being examined. It is found that the section behavior, including occurrence of local buckling, stress distribution form after buckling and ultimate strength, is strongly dependent on the interaction between flange and web. The “plastic effective width” method (PEM) for the ultimate moment resistance of H-sections bent about strong or weak axis is refined and improved using an adjustment factor, namely cross-section slenderness, which accounts for the interactive effect of the plates under different loading conditions. Finally, PEM is proved to provide satisfactory predictions for H-sections over a spectrum of web and flange width-to-thickness ratios and axial force ratios for both the strong and weak axis bending.