Web Deformation Research Articles

Shear force distribution mechanism of perfobond leiste connectors in joint between corrugated steel web and concrete top slab

Compared to composite bridges with flat steel webs (FSWs), the corrugation shape and significant shear deformation of the steel web in composite bridges with corrugated steel webs (CSWs) will influence the distribution and magnitude of the shear force of connectors in the joint between the steel web and concrete slab. However, these effects have not been considered in current design specifications, which may lead to unsafe designs. This paper investigates the shear force distribution mechanism of perfobond leiste (PBL) connectors in the joint between the CSW and concrete top slab in composite bridges with CSWs. The theoretical solution for the shear force of the joint per unit length is firstly derived based on the elastic bending theory considering the shear deformation of the CSW. Then, finite element simulations using hybrid models of solid and spring elements are conducted to further investigate the shear force distribution of PBL connectors and influencing parameters. The results show that the shear deformation of the CSW has a negligible effect on the shear force of the joint per unit length. In contrast to composite bridges with FSWs, the CSW induces sinusoidal variations in the shear force of PBL connectors, which leads to an increase in the shear force of partial PBL connectors. The amplification factor for the shear force increases with the wavelength of the CSW and the shear stiffness of the PBL connector, while it decreases with the increasing dimensions of the steel upper flange, perforated ribs, and hole spacing. Finally, a calculation formula and corresponding procedure are proposed for predicting the shear force of PBL connectors in the joint between the CSW and concrete top slab for composite bridges with CSWs.

Shear-flexural beam models for free vibration analysis of warpable cross-undeformable box girders

A linear free vibration analysis of a rectangular box girder is carried out by different approaches. A simple yet efficient method is proposed to study the combined effect of shear-lag of the flanges and shear deformation of the web. A new analytical expression for the effective flange width is derived, by using equilibrium conditions under the hypothesis of transverse inextensibility of the flange. The web deformation is also taken into account via an ‘effective shear area’, replacing the traditional shear area, accounting for the reduced geometric characteristics of the cross-section, caused by the shear-lag of the flanges. The effective flange width and the effective shear area are used in classic unwarpable models, namely Euler–Bernoulli and Timoshenko beams. An alternative 2 d.o.f. model for the shear-flexural behavior of box-girders, based on a semi-variational approach, is formulated. Such a model takes warping into account, so it does not require the use of the effective geometric characteristics. Finally, the analytical models proposed are validated by comparison with numerical results supplied by Finite Element analyses.

Mechanical Behavior of Special-Shaped Double-Web Steel-Reinforced Concrete Column Joints

In this paper, five new joints of special-shaped double-web steel-reinforced concrete (SDSRC) columns connected with steel beams are designed. The load-displacement curves, joint yield states and damage forms of the beam ends of the five joints under monotonic loading with the same axial pressure ratio are investigated. Additionally, the hysteresis performance, strength and stiffness degradation under cyclic loading are studied. The results show that the bearing capacity of joints with studs can increase by approximately 10%. Since the arrangement of multiple rows of studs at the connection between the beam web and the column has better force transfer performance and concrete synergy behavior, the failure modes of these joints are plastic hinge formation at the end of the beam, satisfying strong column-weak beam requirements. Moreover, these joints exhibit good ductility and energy dissipation capacity under cyclic loading, and their strength and stiffness gradually decrease. In contrast, joints with single-row studs or without studs at the connection between beam web and column exhibit beam flange buckling rather than full-section plastic hinge formation at the beam end, and tensile deformation of column web is larger. Although these joints exhibit good ductility performance, their energy dissipation capacity is weaker than that of joints with multiple rows of studs at the beam web-column connection.

Experimental study of local – Distortional interaction of press-braked stainless steel lipped channel beams

Stainless steel lipped channel beams are prone to complex buckling modes due to the large width-thickness ratio. An in-depth experimental study of local – distortional interaction of press-braked stainless steel lipped channel beams was conducted. The chemical composition was proved to meet the requirements of European and Chinese standards. A tensile test of four coupons extracted from the press-braked lipped channel beams was carried out to investigate the material properties. A total of 10 specimens composed of 20 press-braked stainless steel lipped channel beams were investigated in the bearing capacity test. The relationship of the vertical displacement of mid-span, vertical displacement of loading points, support rotation, flange deformation and web deformation with the load was obtained, as well as the bearing capacity of each specimen. According to the measured displacement and strain, the development and failure mechanism of local – distortional interaction of stainless steel lipped channel beams were revealed. All test specimens were subjected to local buckling first, then distortional buckling, and finally interaction buckling. Each specimen had a certain post buckling strength. Near the failure load, each specimen experienced a long loading process and showed good ductility. The test results were utilized to assess the existing design methods which were all based on Direct Strength Method for the guidance of engineers. The existing design methods for local – distortional interaction underestimated the bearing capacity of press-braked stainless steel lipped channel beams. The existing design methods for local buckling or distortional buckling of stainless steel beams overestimated the bearing capacity of local – distortional interaction.

The behavior of cambered belts transiting cylindrical rollers

The lateral deformations of webs in roll-to-roll process machines can affect the quality of the manufactured products. Webs with simple nonuniform length variation across their width (camber) will steer toward the long side, leading to the steady state lateral deformation and hence registration. Most previous studies have focused on a cambered web in a free span between two rollers. These studies assume some displacement and slope boundary conditions are known and seek the remaining conditions that would dictate the steady state lateral deformation of the web. This article focuses on the lateral behavior of a cambered web belt transiting between two aligned rollers as the simplest case of multiple span cambered web. Dynamic simulation has been conducted to better understand the response of a cambered web under tension that has been witnessed in tests. There are no boundary conditions enforced and no steady state deformation of the cambered webs. Thus there is no closed-form solution to the lateral movement of a cambered web transits over multiple rollers. This explained why the previous research focused more on the experimental exploration without few theoretical validations. The web travels toward the long side continually from one span to the next until a web guide attempts to return the web to an acceptable lateral location in the process machine.

Dynamic performance of retrofitted steel beam-column connections subjected to impact loadings

In this paper, three steel beam-column connections (welded flange-bolted web (WFB) connection, welded flange plate (WFP) connection and reduced beam section (RBS) connection) were experimentally examined under impact loadings. The impact tests using drop-hammer were carried out to simulate the dynamic behaviour of structural progressive collapse. The influence of strengthening or reducing methods on the impact resistance of steel frame substructure was discussed. The failure modes and the dynamic responses of the impact load and deformation time histories as well as the dynamic rotation and energy dissipation of the substructures were investigated. Test results showed that the upper flange of all specimens experienced local buckling near the plastic hinge section, while no welding seam cracked. For retrofitted connections, the out-of-plane and distortional deformation of steel beam flange and web at the plastic hinge section were measured. All the three connections with weld access holes recommended by American Federal Emergency Management Agency (FEMA) had good rotation abilities and impact loading resistances, and their ultimate rotations were not less than the FEMA350 design limits. The ductility and energy dissipation of two retrofitted beam-column connections were improved, which were better than those of un-retrofitted connections. The finite element analysis (FEA) models of steel beam-column connections were also established using ABAQUS software. The internal force development of connections during the impact loading was examined and the results showed that the strengthening or reducing methods had a profound influence on the formation of catenary action of beam-column connections under the dynamic progressive collapse scenario.

Bending characteristics of composite box girder considering all surfaces shear deformation based on Hamiltonian system

The composite box girder does not satisfy the assumption of flat section in the actual force behavior. The transverse force generated by the bending is transmitted to the shear key through the web, and then transmitted to the wing plate by the shear key. The shear deformation of the channel steel box girder web makes the shear stress of the composite box girder section unevenly distributed on the wing plate. The selection of displacement function caused by shear deformation is often unclear in physical meaning, and analysis and verification that conform to the actual deformation and stress distribution law of the structure are rarely carried out. Aiming at this problem, a microplate shear flow analysis method is proposed. Considering the influence of shear deformation, the shear lag warping displacement function of the composite beam is derived, and the displacement function is corrected according to the self-balance condition of the warping normal stress, which makes up for the defect of the unclear physical meaning of the displacement function. On the problem of solving the control differential equations. For the first time, it is proposed to use Hamiltonian theory to solve the problem, which avoids the problem of solving high-order differential equations in the classical elasticity solving method and the functional variational method based on the energy principle. The stress distribution of the composite box girder under the action of concentrated load and uniform load is analyzed.

Influence of patch load length on resistance of I-girders. Part-II: Numerical research

The research deals with structural response and ultimate strength of patch-loaded steel I-girders without longitudinal stiffeners and with largely spaced transverse stiffeners. Part-I of the research, i.e. experimental research is presented in the companion paper. Numerical analysis of load length influence on the ultimate strength of the girder is presented in the current paper.Based on conclusions from the experimental research geometrically and materially nonlinear finite element models of experimentally tested girders were developed. Special attention is paid in modelling the contact between load block and loaded flange and in modelling the approximate geometrical imperfections of the web that best fit the experimentally measured imperfections. Detailed validation of numerical models is done by comparison of numerical and experimental results. Following data are compared: ultimate loads, deflections of loaded flange, vertical strains at measuring points on the web and lateral web deformations. Good agreement between numerical and experimental results is achieved.Quantification of load length influence on ultimate strength as a main objective of the research is made through parametric numerical analysis. Numerical base containing 143 runs is created in which the load length and web thickness are varied. Other geometrical characteristics and material properties of girders, as well as initial geometrical imperfections of the web, are kept constant which could not be provided in the experimental study. By regression analysis of the results of parametric study a simple correction factor for load length is proposed. Accuracy of the proposed expression is proved through statistical analysis over concerned numerical base.

Influence of patch load length on resistance of I-girders. Part-I: Experimental research

Problem of behaviour and ultimate strength of the centrically patch-loaded steel I-girders without longitudinal stiffeners and with largely spaced transverse stiffeners is analysed. The research is focused on two parameters - load length and initial geometrical imperfections of a girder web. This paper presents the experimental research, while the companion paper includes a numerical analysis of the problem.The experimental campaign is described in detail. Results, comments and conclusions from seven tests are presented. The observed increase of the ultimate strength with the load length increase is not quantified due to the scatter of results which is typical for all previous experimental studies in this field. The scatter of results is a consequence of the intricate initial geometrical imperfections of the web which were measured on the most of the specimens. Following conclusions from the experimental research are used in the companion paper to develop reliable numerical models of the experimentally tested girders. It is necessary to model in detail the contact between load block and loaded flange, to account for the variation of contact pressure during the load application. The initial geometrical imperfections of the web in the load introduction zone have more significant influence on the development of lateral web deformation and thereof the ultimate strength, compared to the web imperfections adjacent to the unloaded flange.Finally, based on the performed experimental research, the companion paper presents a detailed parametric numerical analysis of the problem and proposes a correction factor for the load length.

Experimental study on shaped steel shear connectors used in large-scale composite structures

Steel–concrete–steel (SCS) composite structures are used in immersed tunnels and are superior in capacity, constructional facility, etc. in comparison with traditional structures. L- and T-shaped shear connectors are two typical types of shear connectors used in the composite structures. To investigate the mechanical performances of the connectors, 12 groups of push-out tests were conducted. Interfacial slip, bending deformation of the connector web, and strains on the concrete, were measured. Failure modes of concrete crushing were observed in all tested specimens. Evoked outcomes indicated that the performances of the L- and T-shaped connectors were controlled by the non-reinforced concrete. The strain measured in the tests indicated that stress concentration and concrete crushing were mainly located at the root regions. The shear-force–slip relationship, strain distribution, etc., were further analyzed and discussed. Accordingly, the currently available methods used to evaluate the ultimate strength are discussed. These methods were found to be accurate in the case of the L-shaped shear connectors but too conservative for T-shaped shear connectors. A scaling factor was proposed for modification. Finally, 122 groups testing data was collected for validation, which proved that the modified method has adequate accuracy and can be used in various design applications. The experiment data of the L-shape and T-shape shear connectors with different experimental methods were studied which shows the push-out specimens and beam specimens have similar performance. The results of the experimental study and theoretical analyses indicate that the L-shape and T-shape shear connectors have similar mechanical properties while the T-shape shear connectors have better performance concerning the shear stiffness and the ultimate shear strength.

Theories and Control Technologies for Web Handling in the Roll-to-Roll Manufacturing Process

A continuous roll-to-roll manufacturing process is a next-generation process for the environmentally friendly and low-cost mass production of functional printed devices. Unlike paper product printing, a thin plastic web used as a base film in printed electronic devices is exceptionally vulnerable to elastic and thermal deformations owing to its viscoelastic characteristic, which makes the fabrication of highly integrated printed functional devices very challenging. Herein, we review the representative studies regarding the tension applied to the web during the roll-to-roll process and alternatives for compensating web deformation errors. Also, we introduce the development of the theoretical models expressing the dynamics of tension and lateral motion during the web transporting process. We also discuss applicable controllers for compensating the tension and lateral errors and discuss register errors and associated control techniques. Finally, we summarize the mathematical model applied to the internal stress in wound roll and winding tension control techniques, highlighting the idea that defects in the wound roll can be decreased by controlling the winding tension. The review can be helpful in the design of web dynamic control systems in the multi-layer roll-to-roll manufacturing process.

Experimental Tests of Steel Unstiffened Double Side Joints with Flush and Extended End Plate

AbstractExperimental tests of steel unstiffened double side bolted end-plate joints have been presented. The main aim of the conducted tests was to check the behavior of joints in an accidental situation and possibility of creating secondary mechanism, i.e. catenary action in the scenario of column loss. Two types of end plate joints were tested: flush end-plate (FP) and extended end-plate (EP) with different thickness and different number of bolt rows in each. The tests were carried out on an isolated cross beam-column-beam type system until joint failure. During tests the available moment resistance and rotation capacity of bending joints and also values of tension forces in the beam were determined. The joints with extended end-plate have demonstrated higher bending and rotational capacity than flush end-plate. Significant deformation of column flanges, web and end plate were observed. The fracture of bolts was the failure mode of joints. Obtained results of axial force values in beam exceeded standard requirement what confirmed that the joints with unstiffened web column, flush or extended end-plate possess the ability of development the catenary action.

Analysis of flexural natural vibrations of thin‐walled box beams using higher order beam theory

SummaryIn order to study the influence of high‐order shear deformations and shear lag on the dynamic characteristics of thin‐walled box beams (TWBBs), this paper takes the Hamilton principle as a basis to consider multiple factors such as high‐order shear deformations, shear lag, and cross section rotary inertia of the TWBBs. The vibration differential equations and natural boundary conditions of TWBBs are deduced. On the basis of eight examples of TWBBs with different boundary conditions and span–width ratios, analytical results of this paper are compared with those of the ANSYS finite element method. Both results are in good agreement with each other, and the validity of the calculation method is verified. The effects of higher order shear deformations and shear lag on natural vibration characteristics of TWBBs are analyzed. And some meaningful conclusions are drawn: This theory shows the capability to accurately describe both higher order deformations and shear lag; when the span–width ratio is small, neglecting higher order web deformations will produce a large calculation error; under the action of shear lag, the natural vibration frequency of TWBBs decreases greatly, which cannot be neglected; and both the high‐order shear deformations and shear lag effect increase with increasing mode order and increase with decreasing span–width ratio.

Application of the Nasal Septal Cartilage graft For the correction of nasal deformity of unilateral cleft lip

Background:
 An intranasal surgical approach is often taken in reconstruction of the tip as a part of the cleft rhinoplasty. A rim incision provide maximal exposure to the nasal tip and usually obviates the need for external incisions.
 The asymmetrical nasal deformity of unilateral cleft lip can be resistant to correction. All the components of the nose are involved; the cover, support lining and platform. Pathological anatomy of unilateral cleft nose includes (1) deflection of the nasal tip toward the side of the cleft, (2) posterior and inferior displacement of the dome of the alar cartilage on the cleft side, (3) an abuse angle between the medial and the lateral crura of the alar cartilage, (4) obtuse alar facial attachment, and (5) inward buckling of the alar on the cleft side. The alar-collumella web is unsightly and is difficult to correct in both secondary and primary surgery. The purpose of this article to improve the appearance of the nose by the correction of the alar web deformity in patients with unilateral cleft lip nasal deformities by introducing our cartilage graft technique inside the web.
 Methods:
 The article include 15 patients with alar webbing had underwent cleft lip surgery between May 2002 to July 2015. Most of the patient’s age are ranged between 13-25 years at the time of the surgery. The incision was an open rhinoplasty that including a reverse U shape incision. After that the cleft side was equalized with the dome angle of the healthy side, we use a nasal septal cartilage graft as a stiffy pattern to fix and stabilize the deformed converted web skin. The septal cartilage graft fixed to the cleft side web skin’s inner with (3-4) sutures to maintain the tackling of the vestibular skin. 
 The Results:
 Many views basal and frontal are included postoperatively that have been showed, that the nostril and collummella had better shape. Our results showed that most patients demonstrated correction of the dropping alar and nasal tip and correction of the symmetry of the nostrils. The web cartilage graft was fixed to the deformed cleft side web skin’s inner with 3-4 sutures to prevent the tackling of the vestibular skin. Most of the patients have been followed up for a period ranged fro, 1-15 months.

Responsive Parametric Building Free Forms Determined by Their Elastically Transformed Steel Shell Roofs

The article concerns the unconventional architectural forms of buildings roofed with transformed shells made up of thin-walled steel fold sheets, and a parametric description of how they are shaped. Complicated deformations of flanges and webs, as well as the complex static–strength work of the folds in a shell roof, demand the creation of simplified models regarding the parameterization of such shells and their integration with the general forms of the buildings. To obtain favorable results, it was necessary to write computer applications because of both the complicated problems related to the significant limitations of the transformations, as well as the great possibilities of shaping shell roofs by means of directrices of almost free shape and mutual position. The developed procedures enable the prediction of shapes and states of all the folds in the designed shell. They take account of two basic conditions related to these restrictions, which guarantee that the folds encounter little resistance when matching their transformed forms to the roof directrices, and that their initial effort was as low as possible. The developed procedures required solving a number of issues in the fields of architecture, civil engineering, and structures, and are illustrated with an example of shaping one unconventional architectural form. The interdisciplinary study explains a new insight into shaping such forms.

Review of wound roll stress in roll-to-roll manufacturing of flexible electronics

Flexible electronics has been widely used in many main-stream applications like flexible display, thin-film solar cell, RFID tags, flexible sensors, and so on. Roll-to-roll (R2R) is a kind of method by which flexible substrate can be processed in a continuous way. This kind of method saves time, cost, reduces delay time and increases efficiency, throughput, performance, etc. The typical R2R system mainly consists of unwinding unit, feeding unit and winding unit, where deviation rectification control, tension control, vibration control and position control are needed. By taking full advantages of the deformation characteristics of flexible electronics, the R2R process has become one of the most effective ways in manufacturing flexible electronics. The winding unit is an essential part in the R2R system and the control of the wound roll stress in winding process is one of the main factors affecting the quality and productivity of flexible electronics. A tiny wound roll stress will cause difficulties in storage and transportation. The substrates or the electronic circuits mounted on it may be broken when the wound roll stress is too large. This paper begins with the discussion of common issues and the influence of wound roll stress in winding process. Currently, the web tension and its lateral position are two factors that mainly affect the wound roll stress. The wound roll stress will increase with the augment of the web tension. While a variation of lateral position can cause non-uniform wound roll stress in cross machine direction. Subsequently, the modelling methods and solution methods based on elastic mechanics, Laplace transformation, discrete modelling and finite element method are generalized. The four models are called elastic winding model, viscoelastic winding model, pseudo winding model and FEM winding model respectively. The elastic model is derived to predict wound roll stress of the elastic web. The viscoelastic model is developed to study how the wound roll stress changes with time after winding. In the pseudo model and the FEM model, the effect of thickness variation along the width direction is considered. Then this review analyses the effects of winding speed-induced inertia force, web deformation and its inhomogeneous thickness, temperature, air entrainment, structure of the nip roller and the core shaft on the wound roll stress. The taper tension control and constant tension control methods for wound roll stress and engineering applications in RFID tag packaging, seal lamination and flexible OLED manufacturing are also presented. Finally, this paper forecasts the key problems need to be further studied for the wound roll stress in winding process. The study of wound roll stress may focusing on the following aspects: (1) Conducting wound roll stress studies that considering the effect of thickness variation in machine direction; (2) usually we consider the wound roll as an axisymmetric cylinder, so it is necessary to develop a winding model to deal with the helical structure of the wound roll; (3) when deriving winding models, its necessary to consider the discontinuous contact between layers.

Reeling in the prey: fishing behaviour in an orb web spider.

When an insect is intercepted by a spider web, spiders quickly locate the prey and run towards it. Once they make contact with the prey, they immobilise it and retrieve it to the centre of the web or the retreat for consumption. However, in rare circumstances, the spider can also pull the prey towards itself either while running to the prey or from a stationary position, a behaviour termed as 'reeling'. Reeling is paradoxical as it can lead to web deformation or damage, thereby jeopardising future foraging success. Reeling may increase the retention time for heavier prey or information acquisition with respect to the prey's identity, especially when these prey can cause damage to either the web or the spider itself. We explored the function of reeling behaviour in a neotropical orb web spider Verrucosa arenata We show that spiders performed reeling behaviour irrespective whether they were approaching heavy or light prey, but they changed their trajectories of approach. Spiders approached heavier prey more slowly than light prey and they showed a significantly higher frequency of change in velocity. We discuss these findings in the context of prey capture strategies and prey recognition.

Buckling of parallel purlins inter-braced by sag-rods

This paper studied buckling of parallel Z- and C-purlin systems inter-braced by sag-rods at mid-span under pure hogging moment. The purlins are connected to metal sheeting by self-drilled screws and the lateral movement of the top flange is prevented. The paper studied first in detail the buckling of a single purlin, and then buckling of parallel purlin systems. The alternate offset of the sag-rods in adjacent bays and the local deformation of the purlin web have been taken into consideration in parallel purlin systems. For one-purlin system, the buckling moments are given, valid for different combinations of sag-rod and distributed rotational stiffness. The threshold stiffness of the sag-rod, at which the buckling mode changes from symmetrical buckling to anti-symmetrical buckling, is also given. For parallel purlin systems, the buckling moments are calculated by the formulas of one-purlin system, but with a reduced equivalent sag-rod stiffness used in the calculation. Numerical examples for the reduced sag-rod stiffness reveal that an astonishingly large reduction of the sag-rod effective stiffness occurs when the purlin number and the sag-rod offset increase, and the sag-rod stiffness is maximum if the sag-rod is set as close to the bottom flange as possible. And finally some strengthening practices and details are recommended.

Analytical study on web deformation by tension in roll-to-roll printing process

Recently, flexible devices have gained high intentions for flexible display, Radio Frequency Identification (RFID), bio-sensor and so on. For manufacturing of the flexible devices, roll-to-roll process is a good candidate because of its low production cost and high productivity. Flexible substrate has a non-uniform deformation distribution by tension. Because the roll-to-roll process carries out a number of overlay printing processes, the deformation affect overlay printing precision and printable areas. In this study, the deformation of flexible substrate was analyzed by using finite element analysis and it was verified through experiments. More deformation occurred in the middle region in the direction parallel to rolling of the flexible substrate. It is confirmed through experiments and analysis that deformation occurs less at the both ends than in the middle region. Based on these results, a hourglass roll is proposed as a mechanical design of the roll to compensate the non-uniform deformation of the flexible substrate. In the hourglass roll, high stiffness material is used in the core and low stiffness material such as an elastic material is wrapped. The diameter of the core roll was designed to be the minimum at the middle and the maximum at both ends. We tried to compensate the non-uniform deformation distribution of the flexible substrate by using the variation of the contact stiffness between the roll and the flexible substrate. Deformation distribution of flexible substrates was confirmed by finite element analysis by applying hourglass roll shape. In the analysis when using the hourglass roll, it is confirmed that the stress distribution is compensated by about 70% and the strain distribution is compensated by about 67% compared to the case using the hourglass roll. To verify the compensation of the non-uniform deformation distribution due to the tension, deformation measurement experiment when using the proposed hourglass roll was carried out. Experiments have shown that the distribution of deformation is compensated by about 34%. From the results, we verified the performance of the proposed.

Influence of local corrosion on behavior of steel I-beams subjected to end patch loading: Experiments

A total of eleven loading tests were conducted to study the influence of local corrosion on the behavior of steel I-beams subjected to end patch loading. The test parameters included: corrosion pattern (web corrosion, and flange corrosion), corroded length (100mm, 200mm, and 300mm), corroded thickness (4mm, and 6mm), and length of the bearing plate (80mm, and 160mm). Comparisons have been made between the test results and the predicted strengths using current design codes: AISC, AASHTO, and EN1993-1-5. The test results indicate that the web corrosion has a more detrimental effect than the flange corrosion. The behavior of the steel I-beams (e.g., ultimate load, web deformation, and flange and web's strains) is significantly affected by the corroded thickness of the web. However, this is mainly related to the web corrosion within the flange diffusion range. In general, the web local yielding provisions in AISC and AASHTO give the best prediction.