Shear Stress Analysis of Corrugated Web Girders for Bridges

Long span beams with heavy load require increasing the thickness of web and in many cases using a number of stiffeners needs to improve the lateral buckling difficulty. Development and application of corrugated steel web provides facilities to modify the web thickness of beam girders in the design and construction procedure. The attractiveness for using corrugated webs in bridges and composite sections has been increased in recent years. The new system combines the usage of either corrugated steel plates as webs or steel or reinforced/ prestressed concrete slabs as flanges.The application of corrugated steel web may reduce the thickness of webs and restricts it between 2 to 5mm while increases the portion of height/thickness of corrugated web girders in industrial structures up and about 260 and even for long span bridges up to 400.Manufacturers have produced different corrugated profiles such as sinusoid, trapezoid and other forms. The investigations show that the most significant weakness of application of the corrugated web beams is failure due to shear stress. The flanges are assumed to provide the flexural strength of the girder with no contribution from the corrugated web, which is assumed to provide the entire shear capacity of the girder. The corrugated web is thus, subjected to an “almost” pure shear stress state. Failure of a corrugated steel web plate may occur by the classical steel yielding of the web under a pure shear stress state. It may also occur by web buckling due to either local instability of any “panel” between two folds or overall instability of the web over two or more panels. An interactive failure mode between these different failure criteria represents another possibility of failure and so many researchers have considered global, local and semi global buckling in phenomena due to shear strength in their research work. In this paper nonlinear 3D Finite Element Model with regarding buckling modes phenomena for shear analysis of different profile shape of available manufacture corrugated webs is intended. The model is verified with published experimental results and sensitivity of the involved parameters is investigated. As presented in the following figure, the post-buckling strength of girders with corrugated steel webs could be investigated by this model. Figure 1: Typical nonlinear load-deflection curve for corrugated web beam under shear stress The geometric parameters that influence the shear resistance of trapezoidal corrugated web girders investigated in this study, involve:1) Corrugation angle 2) Width of the plane sub panel of the web 3) Web thickness 4) Height of the web 5) Corrugation depth of the web. The parameter study is developed for the sine corrugated web by focusing on amplitude of the central curve of the web and the wave length of the central curve of the web. Corrugated web shear capacity is changed by altering of the amplitude and wave length of the sinusoidal corrugated web. These changing manners are presented in the following figures respectively: Figure 2: Shear capacity versus sinusoidal web wave length Figure 3: Shear capacity versus sinusoidal web amplitude Results show, the sinusoidal webs have better performance than trapezoidal webs in the same conditions. The optimum size of trapezoid and sinusoid dimensions depends to the thickness of applied plate for producing the profile. Concerning to the manufacture restriction for production of profile, the study shows that the maximum shear strength will appear in the sinusoid profile for amplitude of 3 to 4 centimeter while in the trapezoid profile the equal dimension for flat and inclined part in the profile provides maximum shear strength.