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This paper presents the behavioural aspects of a skew bridge and compares them with those of the straight counterparts using a 3D Bridge model in Finite Element Analysis software – ABAQUS. To understand the trend clearly, a simply supported RC Bridge was adopted. The results of the bridge model in ABAQUS show that with the increase in the skew angl...
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... designing such bridges means performing more intricate analysis to predict their behaviour. The reason is that skew bridges behave differently from their straight counterparts, Figure 1. Such bridges are characterised by skew angles, defined as the angle between the centre line of traffic and the normal to the centre line of the river. ...
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... deflections of the deck slab can be directly reported by ABAQUS. Figure 11 summarises the deflection scenario of deck slab with the increasing skew angle. , after which it tends to stabilize. ...
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... the trend in deflection pattern shown in Figure 11, it can be inferred that there is a possibility of development of zero stress at the acute angled corner of the slab. Figure 12 summarises the trend in vertical stress of the slab. ...
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... the trend in deflection pattern shown in Figure 11, it can be inferred that there is a possibility of development of zero stress at the acute angled corner of the slab. Figure 12 summarises the trend in vertical stress of the slab. ...
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... expected, Figure 12 is commensurate with Figure 11 illustrating deflection trend. The possibility of the acute corner becoming a zero stress corner is better reflected in Figure 13, where both Vertical and Shear Stress components (S22 and S13 respectively) tend to become zero. ...
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... expected, Figure 12 is commensurate with Figure 11 illustrating deflection trend. The possibility of the acute corner becoming a zero stress corner is better reflected in Figure 13, where both Vertical and Shear Stress components (S22 and S13 respectively) tend to become zero. ...
Citations
... Physical space constraints in urban areas mean it is often necessary to design bridges with non-orthogonal decks. When skew angles are small (< 20°), a skew slab performs similarly to an orthogonal slab in terms of the moment distribution, support reaction and shear force profiles [1,2], and in this scenario the distribution of shear and moment in the skew slab with a smaller skew angle can be easily defined from simple mechanics. However, for slabs with a large skew angle (20°), the reactions and distributions of shear and moment are significantly different form orthogonal slabs and as such more advanced analysis procedures are required [3][4][5]. ...
... Canadian Standards Association, CSA-16 [10] imposes a limit for using an equivalent-beam method to design skewed bridge decks, but no additional guidance beyond this limit. Most of the existing theoretical work on skews bridge decks adopt finite element analysis (FEA) [1,2,11] or grillage analogy method [7,8,12,13], while yielding accurate results, these approaches can be complex and time consuming and do not provide mathematical expressions that can easily be generalised for guidelines or codes of practice. ...
This study presents an experimental and theoretical investigation of the performance of ultra-high performance fibre reinforced concrete (UHPFRC) skew bridge decks. Five simply-supported UHPFRC slabs with different skew angles were tested under monotonically increasing concentrated load. It was observed that an increase in the skewness of a slab led to a more unsymmetrical vertical deflection profile, and also resulted in a decrease in the magnitude of reaction forces at the acute corners and a corresponding increase in the reaction forces at the obtuse corners. The test results also show that, although some reduction in ductility was seen with increasing skewness of a slab, the specimen with over 25° skew angle still maintained a desirable load carrying capacity and ductility compared to those of a conventional RC straight slab. In addition to the experimental investigations, a fundamental mechanics based closed-form model was developed based on strain energy theorem to predict the performance of a UHPFRC skew slab under linear elastic material condition. At its ultimate limit state, a novel yield-line analysis using a numerically-generated mechanics based moment-rotation relationship was adopted to predict the ultimate load carrying capacity of a skew UHPFRC slab. Both the generic analytical procedures were compared and against test results obtained from this study, as well as those reported in literature, and the results show that the models developed can be applied to UHPFRC skew slabs.
Modern highways are designed to be as straight as possible to accommodate greater speed and safety in today’s traffic. However, it is impossible to arrange for a bridge to span straight to the feature it crosses, especially when a relatively straight roadway alignment is required. Here, a ‘skew’ bridge is needed, but it will have a greater span length and create an angle at the support, the implications of which have received little attention in the current literature. The linear static behavior of a simply supported bridge with skewing geometry was investigated in this paper, and the effect of skew angles and their influence on the internal forces of the U-beam bridge at three different span lengths were observed. A three-dimensional (3D) grillage model of the proposed U-beam bridge was created in the STAAD.Pro software. Three different span lengths (15, 20, and 25 m) were investigated at three different skew angles (0°, 15°, and 40°), totaling nine grillage models studied. The BS 5400 and BD37/01 were used to design and analyze the bridge. The variation of bending moment and shear force was investigated using various skew angles and span lengths. The analysis has revealed that a non-skewed bridge behaves similarly to a one-way simply supported slab, in which load was transferred directly to the support. The analysis also showed that a skewed bridge developed a high shear force that was concentrated at the obtuse corners of the bridge deck. The load distribution of a skewed bridge was based on the shortest distance between the supports, which was located in between the obtuse corners. The grillage analysis was extended to a parametric study to further investigate the behavior of bridges under varying span lengths and skew angles. The study found that skew angle variation had a greater impact on bending moment demand and shear force demands than span length variation. This study also revealed that a bridge with a relatively low skew angle, specifically 15° or less, can be treated as a non-skewed bridge because the bending moment and shear force demands were found to be comparable.
The present study investigates the structural performance of asymmetrically skewed and curved ultra high-performance fibre-reinforced concrete (UHPFRC) slabs/bridge decks through both experimental and theoretical investigations. Four slabs were constructed with varying skew and curvature angles and tested under increasing concentrated loading. In addition to the experimental program, closed-form models based on the method of virtual work and Castigliano’s second theorem were developed to predict the reaction forces and deflections at the mid-span of the skewed and curved slabs within the linear elastic state. Closed-form solutions were developed based on yield-line theory in conjunction with a mechanics-based moment-rotation model to predict deflections at the ultimate state, and a thorough finite-element analysis implementing non-linear material models in conjunction with damage modelling was performed to observe the full-range structural performance of the slabs. A parametric study was performed to examine the effect of skew and curvature angle on deflection, shear, bending and torsion. The generic analytical procedures and finite-element model were compared against experimental results obtained from the study and results show that the models can be applied to UHPFRC asymmetrically skewed and curved slabs.
