Shear-Lag Effects in Three-Span Continuous Box Girder

Abstract:

The physical explanation of shear lag is given in this paper. The shear lag effects can be attributed to the abrupt change of shear stress at web-flange junction. The abrupt change at the junction of shear stresses changes the magnitude of the flange bending stresses, which attenuates gradually with increasing distances from the web. Meanwhile, the abrupt change of shear stresses from zero to the flange shear stress also influences the bending stress state at the centerline of the flange. The method to determine the shear lag effects has been given, which is based on the Euler-Bernoulli elementary theory of bending, and the calculated results are in good agreement with the experimental results. Considering the transversal distribution of the shear stress at the junction, the flange real bending stress could be calculated on the section. The change of the shear stresses decreases the magnitude of the bending stresses in tension, but increases the magnitude of the bending stresses in compression. The shear lag effects in continuous box girder are different from that in the simply supported box girder. The reaction force of the continuous support would generate an abrupt change of the shear forces between the two sides of the support, and the real bending stresses beside the support would vary significantly due to shear lag effects. The ratio of real bending stress to standard bending stress is not the proper index to reflect the shear lag effects, but the real bending stresses could represent the shear lag effects and should be paid more attention to in design.

• Periodical: Applied Mechanics and Materials (Volumes 90-93)
• Pages: 2696-2704
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.90-93.2696
• Online since: September 2011
• Authors: Yu Li Dong, Yuan Yuan Fang, Jun Li Lv
• Keywords: Abrupt Change, Continuous Box Girder, Real Bending Stress, Shear Lag, Shear Stress, Varying Depth

References

[1] Chang, ST, and Ding, Y (1988). Shear Lag Effect in Box Girder with Varying Depth. Journal of Structural Engineering, 114(10), 2280-2292.

DOI: 10.1061/(asce)0733-9445(1988)114:10(2280)

[2] Chang, ST, and Fang, ZZ (1987). Negative Shear Lag in Cantilever Box Girder with Constant Depth. Journal of Structural Engineering, 113(1), 20-35.

DOI: 10.1061/(asce)0733-9445(1987)113:1(20)

[3] Evans, HR, Ahmad, MKH, and Kristek, V. (1993). Shear lag in composite box girders of complex cross-sections. Journal of Constructional Steel Research 24(3), 183-204.

DOI: 10.1016/0143-974x(93)90043-r

[4] Foutch, DA, and Chang, PC (1982). A Shear Lag Anomaly.Journal of the Structural Division, 108(ST7), 1653-1658.

DOI: 10.1061/jsdeag.0005995

[5] Kuzmanovic, BO, and Graham, HJ (1981). Shear Lag in Box Girders. Journal of the Structural Division, 107(ST9), 1701-1712.

DOI: 10.1061/jsdeag.0005777

[6] Luo, QZ, and Li, QS (2000). Shear Lag of Thin-Walled Curved Box Girder Bridges. Journal of Engineering Mechanics, 126(10), 1111-1114.

DOI: 10.1061/(asce)0733-9399(2000)126:10(1111)

[7] Luo, QZ, Li, QS, and Tang, J (2002a). Shear Lag in Box Girder Bridges. Journal of Bridge Engineering, 7(5), 308-313.

DOI: 10.1061/(asce)1084-0702(2002)7:5(308)

[8] Luo, QZ, Wu , YM, Tang, J, and Li, QS (2002b). Experimental Studies on Shear Lag of Box Girders. Engineering Structures, 24(4), 469-477.

DOI: 10.1016/s0141-0296(01)00113-4

[9] Okui, Y, and Nagai, M (2007). Block FEM for Time-Dependent Shear-Lag Behavior in Two I-Girder Composite Bridges. Journal of Bridge Engineering, 12(1), 72-79.

DOI: 10.1061/(asce)1084-0702(2007)12:1(72)

[10] Prokic, A. (2002). New Finite Element for Analysis of Shear Lag. Computers and Structures 80(11), 1011-1024.

DOI: 10.1016/s0045-7949(02)00036-6

[11] Song, QG, and Scordelis, AC (1990). Shear-lag Analysis of T-, I-, and BoxBeams. Journal of Structural Engineering, 116(5), 1290-1305.

[12] Taherian, AR, and Evans, HR (1977). The Bar Simulation method for the calculation of Shear Lag in Multi-cell and Continuous Box Girders. Proc., Institution of Civil Engineers, Part 2, 63, 881-897.

DOI: 10.1680/iicep.1977.3084

[13] Van, DK and Narasimham, SV (1976). Shear Lag in Shallow Wide-Flanged Box Girders. Journal of the Structural Division, 102(10), 1969-1979.

DOI: 10.1061/jsdeag.0004453