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The effect of pile-cap elevation and skew angles on the local scour brought on by clear-water flow around complex bridge piers was investigated experimentally. The complex Selebat and suspension bridge piers in the Al-Muthana and Al-Basra Governorates, respectively, were replicated using two river models scaled at a ratio of one to fifty. Three different pile-cap altitudes and four different pier skew angles (0, 30, 45, and 60) were varied in the experiment. The results show that the equilibrium depth of scour (ds) is greatly increased by even a little skew angle added to previously aligned piers. Due to its wide-pier characteristic, the column contribution to the scour depth becomes predominate when a pier is located asymmetrically in relation to the flow. Three forms of pier skewness were distinguished: aligned piers (=0°), slightly skewed piers (=30°), and severely skewed piers (45°). The influence of pile-cap and pile group on the scouring action decreased as the skewness increased. Furthermore, equilibrium scour holes often reveal pier components uniformly, independent of the undisturbed bed level, particularly strongly skewed piers with entirely buried pile-caps. This study provides insightful information on the roles of pile-cap height and skew angles in flow-induced scouring, which may help designers and maintenance professionals develop more efficient design and preventative measures. [ABSTRACT FROM AUTHOR]

Currently, there is no research and few valid experiments of pile caps. And shear failure mechanism of a pile, exterior column and foundation beam and pile caps in RC structure is not resolved yet under bi-lateral loading. Therefore, a performance evaluation method based on mechanical behaviour for pile caps has not been established. First, the fracture type was specified from the experimental results. Secondary, the ultimate strength formula of the pile cap was proposed based on the previous experimental results. It is a theoretical formula based on the truss-arch theory. It was confirmed that this formula can accurately evaluate the ultimate strength of the pile cap.

Prediction of maximum scour depth at complex bridge piers is frequently decisive for the safe design of bridges. Some methods are available for this purpose but, due to the discrepancies of their predictions, such methods deserve further validation on the basis of new and independent data sets. For this purpose, clear-water experiments were performed by systematically varying the pile-cap elevation of a particular pier shape. Equilibrium scour depths were reached and measured and the comparison of predictions with measurements was established. The method of Sheppard and Renna, published in 2005, was found to predict with the highest accuracy the attained results for the tested complex pier. However, it should be stressed that this method slightly underestimates scour when the pile cap is out of the water or partly imbibed in the flow. It also under-predicts the scour depth when the pile cap is deeply buried in the bed. [ABSTRACT FROM AUTHOR]

Soil arching has a significant effect on the behaviour of pile-supported geogrid-reinforced embankments due to its complex mechanics. In this study, a three-dimensional finite-element model was established to investigate the development of soil arching during the construction and static loading test on an embankment. The model was verified by comparing the variations in earth pressure on the pile cap with the measured data from well-instrumented full-scale model tests. A good agreement was found between the computed and measured data. The experimental and numerical results consistently showed that the arch foot moves from the edge to the centre of the pile-cap under static loading. Finally, the stress contours are presented to illustrate the development of soil arching during the processes of embankment construction and static loading. [ABSTRACT FROM AUTHOR]

Abstract: Steel H-shaped piles are widely used in bridge foundations, but studies on their connections with reinforced concrete pile-cap are quite limited. This paper reports experimental results from monotonically loaded static tests on model steel H-pile to pile-cap connections,in which the piles were subjected to tensile loading or horizontal loading with the bending in the strong or weak bending directions of the H piles. The model H-pile was shallowly embedded into the footing and anchored by four steel bars welded to the web of the H shape. The tests indicate that H-pile-footing connections were effective in transferring vertical and lateral loads. The results of load–displacement analysis show that the connections can sustain a certain amount of moment, though there is no specific design procedure in current codes. A method modified from a previous study by the first author can predict the capacity reasonably well. The study also shows that the FEM analyses can capture the load and deformation relationship and load carrying capacity of the steel H-pile to pile-cap connection satisfactorily. [Copyright &y& Elsevier]