Trapezoidal Corrugated Steel Webs Research Articles

Deformation of a Tapered Box Girder with Trapezoidal Corrugated Steel Webs Considering the Resal Effect: Theory, Experiments, and Numerical Simulations

Deformation of a Tapered Box Girder with Trapezoidal Corrugated Steel Webs Considering the Resal Effect: Theory, Experiments, and Numerical Simulations

Shear stress migration in a tapered girder with trapezoidal corrugated steel webs

This study conducted a comprehensive investigation into the shear stress migration of a tapered prestressed concrete (PC) continuous box girder bridge with trapezoidal corrugated steel webs (TCSWs) throughout the entire construction process, including cantilever construction, structural system transformation and external prestressing tendon tensioning. The results revealed that the basic assumptions, which state that TCSWs bear all the shear force and that only the vertical component of the external prestressing contributes to shear stress when considering its contribution, are not valid for the shear design of tapered PC girder bridges with TCSWs. The horizontal component of the external prestressing and bending moments can cause additional shear forces via the Resal effect, which results in the migration of the shear stresses between the curved bottom concrete slabs and TCSWs. This study investigated the mechanism through which the Resal effect and external prestressing influence the migration of shear stress in the entire construction process. The results revealed that within continuous girders, the Resal effect exhibits both positive and negative implications. Specifically, the negative Resal effect exerts an unfavorable influence, resulting in an increase in the shear stress experienced by the TCSWs. Moreover, this study introduced a modified shear method that that takes into account the influence of bending moments and the horizontal component of external prestressing. In contrast to basic shear methods, this approach provides notably heightened accuracy.

Shear force transfer efficiency of tapered bridges with trapezoidal corrugated steel webs

This study investigated the shear force transfer mechanism in a prestressed concrete (PC) tapered box girder bridge with trapezoidal corrugated steel webs (TCSWs) throughout the cantilever construction process by theoretical analysis, experimental verification, and finite element (FE) simulation. It has been determined that the assumption made in the current standards that TCSWs completely bear the shear force is inaccurate when designing tapered girders with TCSWs. The bending moment can cause a redistribution of shear force in a tapered case, which leads to the transfer of shear force from the TCSWs to the curved bottom flanges, resulting in the TCSWs and curved bottom flanges resisting shear force together. This study also reveals the shear force transfer efficiency in the maximum cantilever stage of the bridge. The results indicate that the shear bearing mechanism of the girder undergoes a gradual transition from a state where TCSWs are the primary shear resisting member at the section near the free end to a state where both TCSWs and the curved bottom flange collaborate to resist shear force as the section moves towards the pier. The study suggested that the maximum shear bearing ratio of the curved concrete bottom flange can reach 60.55% at the section near the pier, starting to replace the TCSWs as the main shear bearing member. Consequently, the shear force calculation method recommended by the existing standards may result in substantial computational errors, with the maximum error reaching as high as 155.62%.

Panting Fatigue of Trapezoidal Corrugated Steel Webs with Mixed-Mode Cracks

Trapezoidal corrugated steel webs under panting fatigue are represented by repeated cyclical out-of-plane deflections of their subpanel with mixed-mode cracks. Compared to stiffened flat webs, notable fatigue crack formation could take place along with local deflection. Fatigue tests were conducted for nine composite girders with slender webs and varied corrugation dimensions. Nearly all test girders showed notable local and interactive shear buckling at the corrugated web panel and the panting fatigue cracks are formed under repeated cyclical deflection while the compression and tension flanges remain intact. Fatigue cracks are initiated at the junction between the vertical (longer) edge of the subpanel and the boundary of the out-of-plane deflection region. The crack propagation paths appear to deviate from the original vertical edge due to buckling induced out-of-plane deflection under mixed-mode stress condition. The test results demonstrate that the Category B’ and Category E suggested by the AASHTO LRFD bridge fatigue design provisions related to the principal stress range and the nominal membrane shear stress range respectively can be considered for the prediction of the fatigue life of trapezoidal Corrugated steel webs in test girders. An appropriate allowance of both the shear stress along the vertical web edge and tension stress from the diagonal plastified tension band is given for the mixed-mode stress intensity factor. The proposed fatigue life prediction allowing for mixed-mode crack growth mostly compares well with test results and its further improvement for the case with higher web panel slenderness ratio is discussed.

Neural network-based analytical model to predict the shear strength of steel girders with a trapezoidal corrugated web

Corrugated webs are used to increase the shear stability of steel webs of beam-like members and to eliminate the need of transverse stiffeners. Previously developed formulas for predicting the shear strength of trapezoidal corrugated steel webs, along with the corresponding theory, are summarized. An artificial neural network (ANN)-based model is proposed to estimate the shear strength of steel girders with a trapezoidal corrugated web, and under a concentrated load. 210 test results from previous published research were collected into a database according to relevant test specimen parameters in order to feed the simulated ANNs. Seven (geometrical and material) parameters were identified as input variables and the ultimate shear stress at failure was considered the output variable. The proposed ANN-based analytical model yielded maximum and mean relative errors of 0.0% for the 210 points from the database. Moreover, still based on those points, it was illustrated that the ANN-based model clearly outperforms the other existing analytical models, which yield mean errors larger than 13%.

Shear Strength of Trapezoidal Corrugated Steel Webs for Horizontally Curved Girder Bridges

Curved composite girder bridges with corrugated steel webs (CSWs) have already been constructed around the world. However, limited work has been done on their shear behavior. In this paper, the corrugated steel web (CSW) in horizontally curved girders (HCGs) is treated as an orthotropic cylindrical shallow shell, and the analytical formula for the elastic global shear buckling stress is deduced by the Galerkin method. Calculation tables for the global shear buckling coefficient for a four-edge simple support, for a four-edge fixed support, and for the two edges constrained by flanges fixed and the other two edges simply supported are given. Then, a parametric study based on a linear buckling analysis is performed to analyze the effect of the curvature radius and girder span on the shear buckling stress. Analytical and numerical results show that the difference of shear buckling stress of CSWs between curved girders and straight girders is small, so the shear design formulas for straight girders can be applied for curved girders. Finally, a series of tests were performed on three curved box girders with CSWs. Similar to CSWs in straight girders, the shear strain distributions of CSWs in HCGs are almost uniform along the direction of the web height and the principal strain direction angles are close to 45°. For the three specimens, CSWs carry about 76% of the shear force. In the destructive test, shear buckling after yielding occurred in all specimens which is in good agreement with the theoretical prediction, which means that the analytical formulas provide good predictions for the shear buckling stress of CSWs in HCGs and can be recommended for design purposes.

Normalized shear strength of trapezoidal corrugated steel webs: Improved modeling and uncertainty propagation

This paper presents a comprehensive analysis of mathematical models for estimating the shear strength of trapezoidal-corrugated steel webs. The existing database of experimental data on trapezoidal corrugated steel web beams and girders is updated by adding more test results, yielding a total of 144 tests. The three-parameter model, previously developed by the authors based on Richards equation is reduced to a two-parameter improved version based on Hill equation. Both models were found to have, essentially, the same performance when compared against test results of the updated database. Based on the Akaike Information Criterion, the new model was retained. The performance of the improved and previously published models is reviewed and tested against the updated database of test results. It was found that the improved model performed better than the existing models in many aspects. An uncertainty analysis was performed on the proposed model considering both, geometric and material parameters as random variables. Bootstrapping and the Point Estimate Method (PEM) were employed to propagate uncertainty and construct confidence intervals for the normalized shear strength. It was found that, overall, the coefficient of variation of the normalized shear strength increases with the slenderness ratio.

Shear behaviour of girders with trapezoidal corrugated steel webs - an experimental study

Shear behaviour of girders with trapezoidal corrugated steel webs - an experimental study

Neural Network-Based Analytical Model to Predict the Shear Strength of Steel Girders with a Trapezoidal Corrugated Web

Corrugated webs are used to increase the shear stability of steel webs of beam-like members and to eliminate the need of transverse stiffeners. Previously developed formulas for predicting the shear strength of trapezoidal corrugated steel webs, along with the corresponding theory, are summarized. An artificial neural network (ANN)-based model is proposed to estimate the shear strength of steel girders with a trapezoidal corrugated web, and under a concentrated load. 210 test results from previous published research were collected into a database according to relevant test specimen parameters in order to feed the simulated ANNs. Seven (geometrical and material) parameters were identified as input variables and the ultimate shear stress at failure was considered the output variable. The proposed ANN-based analytical model yielded maximum and mean relative errors of 0.0% for the 210 points from the database. Moreover, still based on those points, it was illustrated that the ANN-based model clearly outperforms the other existing analytical models, which yield mean errors larger than 13%.

Normalized shear strength of trapezoidal corrugated steel webs

Steel corrugated webs are vertical and lightweight plates responsible for carrying large in-plane loads before buckling. Three modes of shear failure are typical for these elements: local, global, and interactive shear buckling. In this paper, previously published analytical models for the estimation of the shear strength of trapezoidal corrugated webs are summarized, and a new model is developed. The proposed model takes into account the interaction between the modes of shear buckling. Twelve shear-critical corrugated web steel beams (CWSBs) were manufactured and tested to failure. The results were added to update the existing database, resulting in 125 test results, which were then used to compare the performance of developed and existing models. The new model is shown to be more accurate than previously published models for estimating the shear strength of corrugated steel webs, allowing for more economic designs.

Analysis of local elastic shear buckling of trapezoidal corrugated steel webs

The local elastic shear buckling strength of trapezoidal corrugated steel webs is investigated using finite element (FE) and theoretical analyses. The local elastic shear buckling strength is represented by the local elastic shear buckling coefficient, which is obtained from FE analysis. Although inelastic buckling will control the shear strength of most practical corrugated webs, the local elastic shear buckling coefficient is an important parameter in the shear strength calculation. This study shows that the fold width ratio, defined as the longitudinal fold width over the inclined fold width, has a significant influence on the local elastic shear buckling strength as the fold width ratio varies from 1.0 to 2.0. It is shown that the commonly-used local elastic shear buckling coefficient underestimates the local shear buckling strength by a considerable margin when the fold width ratio is greater than 1.0. It is also shown that the local elastic shear buckling coefficient is sensitive to the fold height-to-width aspect ratio, the fold width-to-thickness ratio, and the web corrugation angle, but is insensitive to the flange-thickness-to-web-thickness ratio when it varies from 5 to 15. Based on regression of FE analysis results, a formula is proposed to improve the calculation of the local shear buckling strength, in which parameters such as fold width ratio, fold aspect ratio, fold width-to-thickness ratio, and corrugation angle are taken into account.

Shear strength of trapezoidal corrugated steel webs

Shear strength of trapezoidal corrugated steel webs is an important issue for the design of box girder bridges with trapezoidal corrugated steel webs. Eight H-shape steel girders with trapezoidal corrugated webs are firstly tested to investigate the shear behavior of webs. An extensive parametric study based on the linear elastic buckling analysis is then conducted to derive the simplified formula for calculating the elastic shear buckling strength of trapezoidal corrugated steel webs considering three different shear buckling modes. The proposed formula can give more satisfactory results for predicting the elastic shear buckling strength than some available formulae provided in the literature when compared with the numerical results. Furthermore, the nonlinear buckling analysis is conducted to intensively investigate the shear strength associated with initial geometric imperfections, and the formulae of the shear strength are proposed. Good agreements can be observed between the results calculated using the proposed prediction formula in this paper and the experimental results, and a design formula is also recommended for the routine shear design of trapezoidal corrugated steel webs.

Shear strength of trapezoidal corrugated steel webs

Corrugated webs are used to increase the shear stability of the steel webs of beams and girders and to eliminate the need for transverse stiffeners. This paper focuses on the shear strength of corrugated steel webs with trapezoidal corrugations. Previously developed formulas for predicting the shear strength of steel trapezoidal corrugated webs, along with the corresponding theory, are summarized. A new formula is developed, which considers interaction among the various shear failure modes. More than 100 test results from previous research are organized and evaluated according to relevant test specimen parameters. The conditions of many of these tests are found to be inconsistent with the theoretical conditions assumed in deriving the shear strength formulas. The various formulas for predicting shear strength are then compared with selected test results. The new formula is shown to be more accurate than previous formulas for estimating the shear strength of corrugated steel webs.