A Study on Structural Performance of Non-Prismatic Girders with Double Corrugated Stiffened Steel and Composite Webs

There are some limitations to the use of conventional flat plate web steel girders such as poor web stability and low buckling strength. To overcome these kinds of problems, the idea of using steel corrugated webs to girders has been introduced for achieving enhanced structural performance. The existing studies on bridge girders with steel corrugated webs are focused on single corrugated web girders only. According to previous researches, large forces generated on the girders result in buckling of single corrugated web. This paper focuses on Double corrugated web girders. The Double corrugated web girders can be strengthen either by providing stiffeners along with the corrugated web or by making the web as a composite one.This paper consists of investigations on Nonprismatic girders with Double Corrugated Stiffened Steel Web (DCSSWG) consist of two stiffened corrugated steel webs with steel flanges and also on Nonprismatic girders with Double Corrugated Composite Web (DCCWG) having UltraLightweight Cement Composite(ULCC) fill in the space between two corrugated steel webs. Structural performance of Single and Dual Non-prismatic girders with Double Corrugated Stiffened Steel Webs and Double Corrugated Composite Webs having different tapered ratios are investigated using ANSYS 16.1 software. The results obtained from the study have shown that Non prismatic girders with Double Corrugated Composite Webs show more strength and load carrying capacity as compared to Double Corrugated Stiffened Steel Webs for the same tapered ratio. The effect of Flat flanges (FF), Hollow flanges (HF) and Composite flanges (CF) on the performance of Non prismatic girder with Double Corrugated Composite Webs was also investigated under its static structural performance. The results showed that, Double Corrugated Composite webs in girders with UltraLightweight Cement Composite filled Hollow Section Flanges or Composite Flanges showed better strength, better load carrying capacity than that of Flat Flanges and Hollow Flanges. Keywords— Tapered ratio, Nonprismatic girder, Corrugated web


INTRODUCTION
Bridge girders with corrugated webs have a number of advantages such as more out-of plane stiffness, higher buckling resistance and shear capacity, excellent strength and web stability than that of conventional flat web girders. Some examples of bridges provided with corrugated steel web girders are the Maupré Bridge constructed in France and the Hondani Bridge constructed in Japan. According to previous researches, large forces generated on the girders result in buckling of single corrugated steel webs. For improving its strength and web stability, Double corrugated webs can be provided. That is, the girder will consist of two corrugated steel webs which are placed parallel and separated by a small gap in between them. So that the web portion will be thick. The present study focuses on Double corrugated web girders. The purpose of this paper is to obtain numerical modelling results on Single and Dual linearly tapered girders (Nonprismatic girders) with Double corrugated webs. A tapered girder is wider at one end than the other, giving a tapered appearance to the member and the term Tapered ratio is the ratio between maximum web height to minimum web height of tapered girders (Non-prismatic girders). In this paper the effect of Flat Flanges (FF), Hollow flanges (HF) and Composite flanges (CF) on the performance of Non prismatic girder with Double Corrugated Composite Webs (DCCWG) was also investigated.  [3] conducted investigations on prismatic single corrugated web girders and patch load resistance was determined. it was showed that loading length, flat flange thickness and also girder span have a significant effect on patch loading resistance and buckling strength of girders. B. Kovesdi et al. [4] investigated Interacting stability behavior of steel I-girders with single corrugated steel webs. The results showed that interacting stability depended more on ratio of flange to corrugated web patch loading resistance of prismatic steel I-girders. M. F. Hassanein, O.F. Kharoob [11] conducted study on the single corrugated steel webs of tapered bridge girders. From the study, the increase in shear strength was found to be linear with the web thickness increment of the linearly tapered corrugated steel webs. E. Zevallos et al. [5] presented a study on shear performance of tapered web panels of the linearly tapered bridge girders with single corrugated steel webs. It was observed that web thickness of girders has a greater influence on their shear behaviour. Sihao Wang et al. [13] conducted study on prismatic steel I-girders with single corrugated webs for various stiffener arrangements. From the study it can be observed that strength and stability of corrugated web with vertical stiffeners was more than that of horizontal stiffeners.
IV. NUMERICAL EVALUATION USING ANSYS 16.1 Numerical models for the study were developed with the Finite Element program ANSYS WORKBENCH 16.1 and the results obtained were compared each other and final inference was made.

A. Numerical Evaluation on Single Non-prismatic girders
Numerical models for Single Non -prismatic girders are developed with the Finite Element program ANSYS 16.1. Numerical modelling of three types of Single Non -prismatic girders were performed -(1) Single Non-prismatic Girder with Double Corrugated Web (No additional stiffeners or no additional material is provided with corrugated web portion of girder), (2) Single Nonprismatic Girder with Double Corrugated Stiffened Steel Web (Here stiffeners are provided in between two Corrugated webs), (3) Single Non prismatic Girders with Double Corrugated Composite Webs (An additional material Ultra-Lightweight Cement Composite (ULCC) fill is provided along with two corrugated webs). The performance of these three kinds of Single Non -prismatic girders was investigated under 4 different tapered ratios of corrugated web such as 1.5, 2,3 and 4 also. All girders were modelled with SHELL 181 elements. The length of three kinds of Single Non -prismatic girders is 4500 mm. Thickness of flat flange is adopted as 20 mm and thickness of corrugated web is 6 mm. Width of flange is taken as 225mm. Height of web is selected according to the tapered ratio of web shown in Table 1. The average height of corrugated web for each model is about 500 mm and weight of girder for each tapered ratio was adjusted to be the same. The geometric details of the corrugated web portion for all type of girder are shown in Fig.1.  The girders are simply supported at both ends and the two points symmetric loading was applied along the total width of the flange by two loading plates. Geometry of Single Nonprismatic Girder is shown in Fig. 2. The performance of Single Non -prismatic Girders with Double Corrugated Web can be improved by means of providing stiffeners with same thickness of web 6mm at suitable intervals as shown in Fig.3. The strengthening of the Single Non-prismatic girder with Double Corrugated Web can be also done by means of making the web portion as a composite one by providing ULCC fill at the hollow space in between two corrugated steel webs as shown in Fig 4. Material properties for steel components and ULCC are shown in Table 2.

B. Numerical Evaluation on Dual Non-prismatic Girders
Numerical modelling of two types of Dual Non -prismatic girders were performed -(1) Dual Nonprismatic Girders with Double Corrugated Stiffened Steel Web (Here stiffeners are provided in between two Corrugated steel webs), (2) Dual Non -prismatic Girders with Double Corrugated Composite Webs (An additional material Ultra-Lightweight Cement Composite (ULCC) fill is provided along with two corrugated steel webs). The performance of these two types of Dual Non -prismatic girders are investigated under 3 different tapered ratios of corrugated web such as 2,3 and 4 also. The girders are simply supported at both ends and the two points symmetric loading was applied along the total width of the flange by two loading plates. Geometry of Dual Non-prismatic Girder is shown in Fig. 9. The performance of Dual Nonprismatic Girders with Double Corrugated Web can be improved by means of providing stiffeners with same thickness of web 6mm at suitable intervals as shown in Fig.3. The strengthening of the Dual Non-prismatic girder with Double Corrugated Web can be done by means of making the web portion as a composite one by providing ULCC fill at the hollow space in between two corrugated steel webs as shown in Fig 4. The material properties, geometric details and other dimensions except the length are same as in case of Single Non-prismatic girders. Here length of Dual girder was adopted as 9000mm. Fig 10 and Fig 11 show Table 4.  Result comparison for Dual Nonprismatic girders is shown is shown in Fig 12. Dual Non -prismatic Girder with Double Corrugated Composite Webs (DCCWG) shows better strength and high load-carrying capacity as compared to Dual Nonprismatic Girder with Double Corrugated Stiffened Steel Webs (DCSSWG) for the same tapered ratio. In all cases load-carrying capacity is observed to be improved slightly with the increase in tapered ratio of steel corrugated web.    Fig 14. V. CONCLUSIONS

C. Numerical Evaluation on Different Flange Effects
The strengthening of Double Corrugated Web by means of providing stiffeners or by making the web portion as a composite one using a composite material was investigated analytically in this paper for different tapered ratios of web. The effect of Flat flanges, Hollow flanges and Composite flanges on the performance of Dual Non prismatic girder with Double Corrugated Composite Webs (DCCWG) was also analysed. The following conclusions are derived from this present paper: • For both Single and Dual girders, the load carrying capacity and strength of Non -prismatic girders with Double corrugated steel webs are affected by tapered ratios of corrugated web. In all cases load-carrying capacity was observed to be improved slightly with the increase in tapered ratio of steel corrugated web of the Non-prismatic girder.

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The strength and load carrying capacity of both Single and Dual Non -prismatic girders with Double corrugated web can be improved by providing stiffeners in between the two corrugated webs or by making the web portion of the girder as a composite one by providing Ultra-Lightweight Cement Composite fill (ULCC fill).

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Both Single and Dual Non prismatic girders with Double corrugated composite web possess more strength and stability and the rate of improvement of strength is excellent for composite web than that of stiffened steel web for the same tapered ratio.

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Adding Hollow Flange at top and flat flange at bottom of the girder resulted in improvement of load carrying capacity by 13 percent than that of Dual Non-prismatic girders with Double Corrugated Composite Web having two Flat Flanges. But adding Hollow flange at bottom results 10 percent decrement in load carrying capacity.

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Adding Composite Flange at top results in 32 percent improvement of load carrying capacity and at bottom results 29 percent increment in load carrying capacity than that of providing two Flat Flanges. The Double Corrugated Composite Webs in girders with ULCC filled Hollow Section Flanges or Composite flanges at top showed highest load carrying capacity and strength than that of other flanges for Dual Non-prismatic Girders.