In bridge engineering, girders with corrugated steel webs have shown good mechanical properties. With the promotion of composite bridge with corrugated steel webs, in particular steel-concrete composite girder bridge with corrugated steel webs, it is necessary to study the shear performance and buckling of the corrugated webs. In this research, by conducting experiment incorporated with finite element analysis, the stability of H shape beam welded with corrugated webs was tested and three failure modes were observed. Structural data including load-deflection, load-strain, and shear capacity of tested beam specimens were collected and compared with FEM analytical results by ANSYS software. The effects of web thickness, corrugation, and stiffening on shear capacity of corrugated webs were further discussed.
The corrugated steel web girder bridges have begun to be built since 1980s in France and Japan and have been gaining increasingly interest and implementation since then. The original flat steel plates were manufactured to corrugated shape and used as webs in bridge girders. By using corrugated steel webs, the thickness of the web could be reduced and reinforcement of stiffener can be avoided, resulting in economical benefits and life span improvement.
Compared with prestressed concrete girders, at the same cross section layout, by using corrugated steel web box girder, it can reduce the weight of web and greatly improve the efficiency of the prestressing and material utilization since webs are under pure shear state while flanges are under flexural deformation [
Research in corrugated web girder bridges has been primarily focused on buckling analysis of webs. Li and Guo [
Despite that the parameters effect and design equations have been studied in corrugated steel web girder bridges, experimental studies regarding shear buckling and failure modes as well as the comparison between FEM and experiment are quite limited.
It is necessary to design specimen size according to the testing instrument in order to make sure that specimens can be tested on the loading platform. Loading platform is square shaped with a size of 1200 mm × 1200 mm. The bearings are shown in Figure
Experimental supports.
According to the hot rolled H shaped steel and cut T section steel [
Schematic view of Type 1200 corrugated shape (unit: mm).
Supporting stiffener in the specimen support is arranged in pairs. According to specimen design, ultimate bearing capacity of steel beams is expected to be 310 KN and the minimum thickness of stiffener
Layout of web and stiffener.
The flexural capacity of corrugated web steel girder specimen is provided by the upper and lower flanges theoretically. In order to increase its flexural capacity, supporting stiffeners were used as shown in Figure
Details of specimen ends with stiffeners.
Left end
Right end
Elevation and cross section views of H shape steel girder (unit: mm).
Corrugated web
Plain web
Five welded H shape steel girder specimens were fabricated in a factory as shown in Figure
The characteristic parameters of specimen (Unit: mm).
Label | Specimen length | Web | Ripple parameters | Ripple type | Stiffener type | ||||
Height | Thickness |
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C3F | 816 | 330 | 3 | 66 | 54 | 66 | 40 | Trapezoid | Full |
C3H | 816 | 330 | 3 | 66 | 54 | 66 | 40 | Trapezoid | Half |
C2F | 816 | 330 | 2 | 66 | 54 | 66 | 40 | Trapezoid | Full |
C2H | 816 | 330 | 2 | 66 | 54 | 66 | 40 | Trapezoid | Half |
P3F | 816 | 330 | 3 | — | None | Full |
Note: C and P represent corrugated steel webs and plain steel webs, respectively; 3 and 2 represent 3 mm and 2 mm thick webs, respectively; F and H represent types of stiffener which are full stiffener restraint and half stiffener restraint, respectively.
Steel raw materials.
Cutting
Rust removal
Corrugated webs after shear forming.
The rust was removed by using manual grinding machine especially in the welding fillet between web and flange area to prevent strength reduction. The specimen after derusting is shown in Figure
Corrugation profiles of specimen.
To control the manufacturing error of eccentricity between web and centerline of flange, semiautomatic gas shielded welding seams were adopted as the welding procedure. As a result, ER50 type welding wire and 5 mm leg size in fillet weld leg is used to avoid shrinkage in welding line during the cooling process. The welded girder specimens are shown in Figure
Diagram of specimen.
In order to test the mechanical properties of the steel materials, yield strength, elongation and poisson’s ratio, and elastic modulus were tested in accordance with Chinese testing standards. Mechanical properties specimens were sampled by using plasma cutting from corrugated steel girder specimens. The sampling positions are at web, flange, and the stiffener. Three groups of specimens were taken according to the thickness of the steel
Configuration and photos of tensile specimens.
DDL100 electronic universal testing system.
All specimens showed “necking” after strain hardening as shown in Figure
Properties of tensile test.
Label | Yield strength (MPa) | Tensile strength (MPa) | Yielding to tensile ratio | Elastic modulus (×105 MPa) | Poisson ratio |
Elongation (%) |
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2-1 | 342.915 | 398.926 | 0.86 | 1.805 | 0.23 | 28.0 |
2-2 | 337.086 | 404.073 | 0.83 | 1.862 | 0.19 | 28.8 |
2-3 | 342.074 | 392.159 | 0.87 | 1.860 | 0.22 | 30.0 |
3-1 | 339.177 | 418.110 | 0.81 | 2.030 | 0.24 | 30.0 |
3-2 | 345.123 | 404.086 | 0.85 | 2.031 | 0.25 | 30.4 |
3-3 | 341.663 | 421.652 | 0.81 | 2.032 | 0.23 | 32.6 |
10-1 | 302.755 | 429.751 | 0.70 | 2.059 | 0.28 | 27.8 |
10-2 | 306.785 | 444.722 | 0.69 | 2.059 | 0.27 | 28.0 |
10-3 | 299.058 | 425.141 | 0.70 | 2.059 | 0.26 | 27.4 |
Failure modes of tensile specimens.
2 mm specimen
2 mm specimen
Fracture failure
Necking
Fracture failure
2 mm specimen failure mode
10 mm specimen failure mode
Three-point bending test was conducted on corrugated web specimens. Two simple supports were placed on both ends with one single point load in the middle. Test setup is shown in Figure
Test setup.
Elevation view of the web.
Two different buckling modes consisting of local and global buckling were observed in the test. Local buckling is defined as follows: at a certain load, a single folded plate forms a buckling but does not spread to adjacent folded plate. On the other hand, under a specified load, if buckling was formed in more than one corrugated plate, it is considered as the global buckling.
Almost all of the buckling in the test was local buckling except for specimen P3F. However, it should be noted that the local buckling is almost always followed by the global buckling especially for the 2 mm thickness welding corrugated webs specimens. Three different failure modes were observed in the test and were classified in Tables
Failure mode classification.
Mode | Description of failure |
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A | One fold plate of webs was buckled first. As load increased, the buckling line appeared along 60° at upper left corner or bottom right corner, resulting in buckling of adjacent fold plate. |
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B | One fold plate of webs close to top flange was buckled first and then it approached to middle stiffener. As load increased, buckling was developed to flanges longitudinally. Finally the area between flange and webs buckled. |
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C | Web was buckled along the diagonal direction between two adjacent stiffeners and then both sides of the specimens buckled continuously. |
Failure modes and shear capacity of specimens.
Label | Shear capacity |
Failure mode |
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C3F | 296.25 | A |
C3H | 288.35 | A |
C2F | 205.40 | B |
C2H | 197.50 | B |
P3F | 244.90 | C |
Failure modes.
Mode A
Mode B
Mode C
Load-deflection curves of specimen C3F and C3H are in Figures
Load-deflection curve of C3F.
Load-deflection curve of C3H.
Load-deflection curve of specimen P3F is shown in Figure
Load-deflection curve of P3F.
Figure
Load-deflection curve of C2F.
Load-deflection curve of C2H.
Strain gages were installed on the folded plates in the girder specimens. The collected load and strain data were presented in load-microstrain curves for the specimen C2F, which were the typical case for all specimens. As shown in Figure
Load-strain of specimen C2F (Typical).
Top of fold plate F
Middle height of fold plate F
Bottom of fold plate F
Fold plates A, B, and C
The effect of parameters on ultimate load capacity was investigated by using finite element analysis. It included web thickness, web height, flange width, and yield strength of steel.
Geometrical and material nonlinearity were both considered in FEM in structural stability analysis. Triple-line stress-strain relation of steel was adopted in the analysis, and shell element 181 with 4 nodes was used to establish the corrugated web H shape steel girders as well as plain web weld H steel girder FEM analysis model.
Finite element model of the specimen is presented in Figure
Finite element model of specimen.
During the manufacture of the steel girder, residual stress will appear inevitably. Welding simulation of steel girder was carried out by FEM and stresses distribution in web as well as in flange is shown in Figure
Residual stresses distribution.
In corrugated webs
In flanges
Table
Effect of web thickness on shear capacity.
Label | Thickness (mm) | Elastic modulus (×105 MPa) | Experimental (kN) |
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C2F | 1.77 | 1.860 | 205.40 |
C3F | 2.50 | 2.031 | 296.25 |
C2H | 1.77 | 1.860 | 197.50 |
C3H | 2.50 | 2.031 | 288.35 |
Shear capacity of full stiffener reinforcement specimens.
Specimen | Thickness (mm) | Elastic modulus (×105 MPa) | Experimental (kN) | FEM (kN) | Error |
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C2F | 1.77 | 1.860 | 205.40 | 197.95 | 3.63 |
C3F | 2.50 | 2.031 | 296.25 | 293.43 | 0.95 |
Note: Error =
Shear capacity of half stiffener reinforcement specimens.
Specimen | Thickness (mm) | Elastic modulus (×105 MPa) | Experimental (kN) | FEM (kN) | Error |
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C2H | 1.77 | 1.860 | 197.50 | 196.16 | 0.68 |
C3H | 2.50 | 2.031 | 288.35 | 280.00 | 2.90 |
Note: Error =
Table
Comparison of load capacity at different web thickness.
Specimen 1 : Specimen 2 | Ratio of web thickness | Ratio of experimental result | Ratio of FEM result |
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C3F : C2F | 1.41 | 1.44 | 1.48 |
C3H : C2H | 1.41 | 1.46 | 1.43 |
In order to study the effect of corrugation on the shear capacity, specimens with corrugated web and plain web are compared at the same web thickness. Table
Shear capacity of 3 mm specimen.
Specimen | Wave height (mm) | Fold plate width (mm) | Experimental (kN) | FEM (kN) | Error |
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P3F | — | — | 244.90 | 242.54 | 0.96 |
C3H | 40.00 | 66.00 | 288.35 | 280.00 | 2.90 |
C3F | 40.00 | 66.00 | 296.25 | 293.43 | 0.95 |
Note: Error =
Comparison of shear capacity with and without corrugation.
Specimen 1 : Specimen 2 | Ratio of web thickness | Ratio of experimental result | Ratio of FEM result |
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C3F : P3F | 1 | 1.210 | 1.209 |
C3H : P3F | 1 | 1.177 | 1.154 |
It can be inferred from Tables
To study the vertical boundary condition effect on the shear load capacity, specimens with full stiffener and half stiffener reinforced were compared both by FEM and experiment under the same conditions. The outcome was shown in Tables
Shear capacity of 2 mm specimen under two restraint conditions.
Specimen | Web thickness (mm) | Experimental (kN) | FEM (kN) | Error |
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C2F | 1.77 | 205.40 | 197.95 | 3.63% |
C2H | 1.77 | 197.50 | 196.16 | 0.68% |
Note: Error =
Shear capacity of 3 mm specimen under two restraint conditions.
Specimen | Web thickness (mm) | Experimental (kN) | FEM (kN) | Error |
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C3F | 2.50 | 296.25 | 293.43 | 0.95% |
C3H | 2.50 | 288.35 | 280.00 | 2.90% |
Note: Error =
Comparison of shear capacity under different restraint.
Specimen 1 : Specimen 2 | Ratio of experimental results | Ratio of FEM analysis |
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C3F : C3H | 1.03 | 1.05 |
C2F : C2H | 1.04 | 1.01 |
It can be obtained from Table
Figures
Load-deflection curve of C3F.
Load-deflection curve of C3H.
Deformation of C3F in FEM and experiment.
Deformation of C3H in FEM and experiment.
In previous FEM analysis, the model shown in Figure
Shear capacity of specimens with variable web thickness.
Number |
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FEM results (KN) | Load ratio |
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1 | 1.0 | 330 | 330 | 55.49 | 0.271 |
2 | 1.5 | 330 | 220 | 97.95 | 0.478 |
3 | 2.0 | 330 | 165 | 146.54 | 0.617 |
4 | 2.5 | 330 | 132 | 204.71 | 1.000 |
5 | 3.0 | 330 | 110 | 271.80 | 1.328 |
6 | 3.5 | 330 | 94.29 | 344.41 | 1.682 |
7 | 4.0 | 330 | 82.5 | 424.94 | 2.076 |
Note: load ratio = individual load value/load value of number 4.
The buckling modes from FEM analysis with web thickness of 3 mm and 4 mm were shown in Figure
Buckling mode.
3 mm thick web specimen
4 mm thick web specimen
Figure
Load-deformation curves with variable web thickness.
Based on the experimental investigation and FEM analysis on corrugated web H shape steel girder specimens in this study, the following conclusions can be drawn. Two different buckling modes consisting of local and global buckling were observed in the test. Results show a good fit between experimental data and finite element analytical results for load-deflection behavior. Parameters study indicated that as web thickness increases, shear capacity of corrugated web increases significantly at 45% on average. Among all, 3 mm thick corrugated web specimen with full stiffener reinforcement presented the highest shear capacity. It indicated that, under other same conditions, by corrugation arrangement, shear capacity of webs increases 19.4% or so for 3 mm web thickness specimens. It is inferred that, under the same web thickness and corrugation conditions, shear capacities of full stiffener restraint are higher than that of half stiffener restraint condition, at about 3%.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The financial support provided by Science and Technology Grant Scheme of Guangdong Transportation Department (2011-02-46) and the National Natural Science Foundation of China (Project no. 51421064 and Project no. 51208077) and The Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (SRF for ROCS, SEM #47) is gratefully acknowledged.